| profuse007 |
-i just hook up this lil system in my car and driving it down several days after and the sounds cut off.
-i believe i bridge the amp wrong, i prolly mistaking w/ the left/right vs white/red from HUnit to the amp.
-just open the amp and one of the semiconductor has burnt. its black rubber and has double end conductor to the board. the board label it (the semiconductor) TS1.
where can i find this TS1? can someone specify what this semi is is its category? |
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| gearheaddruid |
| Hi, I think what you are looking at is the Thermal Sensor. This is the designation TS1. This is a special fuse that is supposed to open up when a preset temperature is reached. There is not normally a lot of current passed through those so I find it odd that it would burn. If it is burnt, I would think there is a lot more damage to the amp then just that piece. Did you loose the ground connection on the amp? That might cause a problem like that. Regards, Steve |
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| profuse007 |
thanks for the reply. i thot about grounding too. iwill try to remount the ground at a solid spot.
since its a thermal preset protector or whatever it is, can i replace it w/ a fuse to test if the amp still work?
btw, all of the other semi doesnt seem to affected to the naked eye ...... could it fool ones eye?
btw, i tried to look for that piece on www.mouser.com but there are so much thermal sensor. can someone help me find it? i am not familiar w/ semiconductors. |
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| TO-3 |
| Do you have a DMM? You can measure the switchers to see if they are blown. Measure from the tab to pins 1 and 3 and across 1 and 3. If it is short, then the part(s) is bad. The amp will fuction without that thermal sensor, and if it does, then you know you have no other problems. What amp do you have? I have just about all the schematics for the Power Class series. I have a dead PC amp that I will crack open later to see if there is a part number on the TS's. |
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| profuse007 |
Precision Power (PPI, www.DEI.com is the maker)
Mosfet Power Series
PPI-2150M 2x150wrms
300W @ .02%THD
40HM load -12V DC
those are the info i can get on that amp.
btw, the theral sensor (ithink) has no continunity so its fried. the thermal sensor is not a tab-looking or square looking, its a symmetrical tubular structure that looks like a regular resistor but black rubber.
when to think of it what you said, its fried.
any chances?
just to let you know, i have no knowledge of how to build an amp like yall guys. if yall can take me though this w/o givin urself a headache would be much appreciated. the thing that i am only good at is using my DMM to test circuits. |
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| TO-3 |
| OUCH!!!!! That thing is old!!! When I worked at PPI, I had to fix a couple of those things. A PITA!!!! The thermal sensor should not measure low, so it may still be good. Unless it looks visually cracked. Like I said above, measure the switchers, the MosFETs in the power supply, to see if any of those devices are shorted. |
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| profuse007 |
hey am prolly gonna waste ur time but since my hands are somewhat wet, i want to mess w/ the amp to see if i can learn seomthing. so if i can take a pic of the board, can you pin point out what to test w/?
again, i honestly do not know how to test mosfet or relation to transistor, nor switches. what exactly are switches? when you say switches, the only things that comes to mind is relay, but still puzzled.
anything is koo w/ me.
thanks for your times and others here. |
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| TO-3 |
Switchers are what we call the MosFETs in power supplies. When a DC voltage is applied to a transformer, there is a spike of current that occurs, and it induces a voltage in the secondary windings. This is, pretty much, an instantaneous pulse of current and only provides a pulse of power to the secondary. So the 12V, that our automotive electrical system supplies, is worthless as it is. Transformers are used to step-up, or step-down voltage, but they can only work with alternatiing current. With AC, an electromagnetic field induces the secondary wingings with a current. Because of the DC resistance of the coils of wire in each, the primary and secondary, a voltage must occur across each side of the coils. If the secondary has more windings than the primary, then the voltage is stepped-up and if the secondary has less widings, than the voltage is stepped down.
Since the DC voltage of the car system is not really useful for an amplifier, we need to convert this to alternating current, so it can be stepped-up. The 'switchers' are MosFETs that are used to open and close the path of current to ground. So one side is, basically, connected to the battery(+12V), and the other side is connected to ground, through the primary winding of the transformer.
Now we have a IC called a PWM(pulse-width modulator), that chops the DC voltage to a certain duty-cycle(also abbrv. DC) and is connected to the gates of the 'switchers'. This PWM chip is used to turn the MosFETs on and off. This creates AC so the transformer can step-up the voltage to the secondaries.
It's late and it is time for bed. Hopefully this will give you a little insight as to how a switching power supply works. |
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| profuse007 |
not really quite understanding what switchers are, but can you explain the actual pin of the switcher(mosFET) and what it does, maybe i can understand it better.
how could i test it? does it need to be desolder? in the mean time ill search the net on more of this mosFET.
is there an analogy to this mosFET chip or a break down of components thats built into this one chip?
BTW, what is the simpliest amp called? maybe i can learn from the simpliest amp and move up to understand whats goin inside the chip.
iono if you taken circuits in college or whatever, do you learn in stuff also? i havent taken the course yet but have to soon. |
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| TO-3 |
The MosFets are TO-220 devices that are mounted on the heatsink. They are called 'switchers' because all they do is turn on and off. Pin 1 is usually the gate and pin 2 is the drain and pin 3 is the source. I stated, up above, the easiest way to test these devices. The SG3525A, is a common PWM chip that is used in many switching power supplies, here is a link: http://rocky.digikey.com/WebLib/On-...a/SG3525A-D.pdf
My computer is being a piece of chit right now and won't let me operated my scanner. I need to reformat my drive and reinstall everything, then I should be able to scan some schematics that will help you visualize what's going on in the switching power suppies.
I'll post more after I fix by f'ing computer. |
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| TO-3 |
| Here is a schematic showing a simple switching power supply. Q1,2 are the switchers in the schematic. Notice that the output pins of U3(pins 11 & 14) are conneted to the gate of the mosfets through R4 and R6. Also, notice that B+ is connected directly to the transfomer, and is grounded through the switchers. |
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| EnvisionAudio |
When did you work for PPI and what did you do for them? I know the old Art series quite well - especially the overabundance of silicone thermal goop they used at the time. :rolleyes:
Do you have the schematics to the A600 Amp? I've got one that has quite a few eroded traces from a little marine trip its former owner went on. I'd like to know where they go. Please let me know at:
envisionelec(at)earthlink(dot)net
Thanks,
Aaron |
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| profuse007 |
| thanks for the info. ill take a look at he schematic once the weekend start. |
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| TO-3 |
| Here is a schematic for a higher-power power supply. Notice the parallel switchers as well as the push-pull drivers used to increase the current supply to the gates. Also, this is a regulated power supply, unlike the one I posted earlier. |
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| profuse007 |
thanks but seeing these kind of schematic for the first time, itll take awhile to understand.
ill post any result later this week.
thanks again |
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| profuse007 |
| am guessin my amp's power supply is design like the second schematic? |
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| K-amps |
| quote: | Originally posted by TO-3
OUCH!!!!! That thing is old!!! When I worked at PPI, I had to fix a couple of those things. A PITA!!!! The thermal sensor should not measure low, so it may still be good. Unless it looks visually cracked. Like I said above, measure the switchers, the MosFETs in the power supply, to see if any of those devices are shorted. |
TO-3,
Back in 1998, I heard that the PPI Powerclass Series was designed by some Ex-Krell engineers. Is that true? Cause I was suckered into buying a PC-2350 powering my woofers and a PC-450 bridged powering my highs. I just love those amps....
Are they as good as I think they are or not?
thanks in advance!!
K- |
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| TO-3 |
| quote: | Originally posted by K-amps
TO-3,
Back in 1998, I heard that the PPI Powerclass Series was designed by some Ex-Krell engineers. Is that true? Cause I was suckered into buying a PC-2350 powering my woofers and a PC-450 bridged powering my highs. I just love those amps....
Are they as good as I think they are or not?
thanks in advance!!
K- |
Mr. Eichenbaum was the engineer that was from Krell, and ended up going back to Krell. As far as I know, he only designed the PPI-2500F1 and the PPI Tube Drivers' audio sections. I don't believe that he did any designs for the Power Class. The PC series is the same architecture as the Art Series, only with different chassis. The engineer that designed the PC amps originally designed the Xtant amps, left to work at PPI, then left to work for JL Audio. |
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| K-amps |
| In your opinion, are they good amps?:) |
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| profuse007 |
b4 i even start, it seems that the mosFETs are overheated. the white thermal contact thingy to the heat sinks are spread everywhere.
i tested, what it seems to be transistors looking (3pins), four different types.
click here for amp pic
the first four blue motorola chip, it seems to be some sort of diodes... i think. then theres the suspected mosFET, all 10 consecutive chips.
-the10 chips has characters on them and its as follow: IRF234 IR8923 5S JN
the suspected chips: 1(gate) and 2(drain) has 12volt constant and the 3(source) has ground. this was tested using a DMM while the blue remote wire is DISconnected.
_______________________________________
the other side of the wall, they seems to be some some sort of transistor looking but testing it, the 1&3 has ~.5V constant.
2N6490 8915 by motorola are the 1st five chip from the left and the following chips has the similar numerical designation.
_______________________________________
the TS1, thermal sensor suspect was cutted out.. dont ask me why...but it was burnt in the middle of the cylinder.
i dont know what exactly know what i am testing...... plz help |
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| profuse007 |
| also notice about the resistor on the right bottm corner, it looks burnt. the resistance is slightly diff from all the others. |
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| EnvisionAudio |
The thermal "sensor" is actually a diode - it's not burnt in the middle - that's the PN gap you're looking at. Put it back in.
I can see right away that Emitter Resistor R55 is burnt to a crisp. Know what that tells me? Q28 is shorted. Others are probably, too. Check and replace those outputs (probably 2N6488/2N6419) then try again. Bad outputs will blow the fuse quickly on any PPI.
Ok, I see that you already mentioned the resistor before I posted. :rolleyes: |
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| TO-3 |
| quote: | Originally posted by K-amps
In your opinion, are they good amps?:) |
Which? The PCs are very nice for SS amps. |
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| K-amps |
| quote: | Originally posted by TO-3
Which? The PCs are very nice for SS amps. |
The PC-2350. Cause I love it! |
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| profuse007 |
that TS1 line, it reads 12volt on my DMM. hows that a diode into it? still confuse.
for now, if the chips are screwed up i really dont know how to test it. i havent test.
i need to know the order of how to test the power switch thingy...... i am confuse.
do i need to worry about the PWM at this time of testing?
can someone pointl out to me what are those chips exactly is.
i know this seems frustrated to yall, am still learning. |
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| TO-3 |
| quote: | Originally posted by profuse007
b4 i even start, it seems that the mosFETs are overheated. the white thermal contact thingy to the heat sinks are spread everywhere.
i tested, what it seems to be transistors looking (3pins), four different types.
click here for amp pic
the first four blue motorola chip, it seems to be some sort of diodes... i think. |
Yes the blue Motorolas are your rectifier diodes.
| quote: |
then theres the suspected mosFET, all 10 consecutive chips.
-the10 chips has characters on them and its as follow: IRF234 IR8923 5S JN
the suspected chips: 1(gate) and 2(drain) has 12volt constant and the 3(source) has ground. this was tested using a DMM while the blue remote wire is DISconnected. |
Do a continuity test between the tab(same as pin2) and pin 1. As these are mosfets, the resistace should be very high. The source's are most likely grounded through the transformer. Those switchers, I think, are obsolete now, but you can still find Z44's that we always used for replacements. You would have to replace all 10 of them with the same parts. Also, if you do need to replace the switchers, replace the gate resistors, that are 47ohms, to 22 ohms.
| quote: | the other side of the wall, they seems to be some some sort of transistor looking but testing it, the 1&3 has ~.5V constant.
2N6490 8915 by motorola are the 1st five chip from the left and the following chips has the similar numerical designation.[quote]
Again, I think these parts are obsolete, but can be replaced with 2N6492 and 2N6488's. You'll have to look at the data sheets for those parts, but if I can recall correctly, the formers are PNP's. You may be able to get by with just replacing the outputs, but sometimes, you may also have to look at the drivers for the outputs, as they may have gotten fried too. But if only one output is shorted, you may only really need to replace that one. R55 is a ballast resistor, and I agree, it should be replaced.
[quote]the TS1, thermal sensor suspect was cutted out.. dont ask me why...but it was burnt in the middle of the cylinder.
i dont know what exactly know what i am testing...... plz help |
Without seeing the part in TS1, I can't recall what the part is. I'll have to think about that. |
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| TO-3 |
| quote: | Originally posted by profuse007
that TS1 line, it reads 12volt on my DMM. hows that a diode into it? still confuse.
for now, if the chips are screwed up i really dont know how to test it. i havent test.
i need to know the order of how to test the power switch thingy...... i am confuse.
do i need to worry about the PWM at this time of testing?
can someone pointl out to me what are those chips exactly is.
i know this seems frustrated to yall, am still learning. |
Do you have an o-scope? |
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| TO-3 |
| quote: | Originally posted by K-amps
The PC-2350. Cause I love it! |
Yes, that amp is truly sick!!!! :cool: |
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| EnvisionAudio |
If you want it back in less than a week. I have all the parts for them in stock. $75 (incl parts) plus shipping to 45420 and it will be good as new.
TS1 is a diode. You'll measure 12V because it is a difference element in a comparator circuit. Once the voltage gets to, say 11.4V, the comparator will trip and power down the amp.
Good luck, or look me up. :cool:
Regards,
Aaron
Envision Electronics |
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| gearheaddruid |
Hi, If I read that correctly, you are measuring 12 volts on the source (middle pin), 12 volts on the gate (left pin looking at top with pins aimed down). Those are blown mosfets! 12 volts on the gate would have them turned on hard. The thing should be drawing a lot of current.
I wold replace the burnt pair of outputs, the power supply mosfets, and check the driver transistors. Then, I would use a current limited power supply to test it. If you missed something, limited current will keep you from frying everything again. If you do not have a current limited supply, try putting an old headlamp in series with the power lead. If something is wrong, the headlight will be bright and should save an expensive smoke show! Regards, Steve |
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| TO-3 |
| quote: | Originally posted by profuse007
that TS1 line, it reads 12volt on my DMM. hows that a diode into it? still confuse.
for now, if the chips are screwed up i really dont know how to test it. i havent test.
i need to know the order of how to test the power switch thingy...... i am confuse.
do i need to worry about the PWM at this time of testing?
can someone pointl out to me what are those chips exactly is.
i know this seems frustrated to yall, am still learning. |
Any luck with the reanimation? |
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| profuse007 |
ill keep yall posted, been busy.
i dnt have a scope, only a DMM w/ most of the functions.
okay tested again and got confuse w/ what yall said. the last pin is the source right? cause that last pin is grounded w/ .1 ohm. again, the first two pin has 12v on all 10 mosfets w/ remote on and off.
plz confirm that those chips are burnt
IRF234 IR8923 5s 3n. if burnt, then i need the z44 type thats comparable to mine, how much? |
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| profuse007 |
for now, i dont care about signals right now, am just looking at the power switch source. what are the things i should be concerning besides replacing the mosfets?
| quote: | the other side of the wall, they seems to be some some sort of transistor looking but testing it, the 1&3 has ~.5V constant.
2N6490 8915 by motorola are the 1st five chip from the left and the following chips has the similar numerical designation.[quote]
Again, I think these parts are obsolete, but can be replaced with 2N6492 and 2N6488's. You'll have to look at the data sheets for those parts, but if I can recall correctly, the formers are PNP's. You may be able to get by with just replacing the outputs, but sometimes, you may also have to look at the drivers for the outputs, as they may have gotten fried too. But if only one output is shorted, you may only really need to replace that one. R55 is a ballast resistor, and I agree, it should be replaced. |
the quote in bold, are you talkin about the physical drivers like subwoofers?
oooooppsss... its IRFZ34 IR8923 5s 3n (not IRF234) |
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| EnvisionAudio |
| quote: | | the quote in bold, are you talkin about the physical drivers like subwoofers? |
No, driver transistors. They are connected to the output transistors and are located in close proximity to them. There are two per channel (I think). These will sometimes die if the outputs are blown.
| quote: | | oooooppsss... its IRFZ34 IR8923 5s 3n (not IRF234) |
IRFZ34 can be replaced with IRFZ44N - and I recommend it for better durability. Digikey and Mouser both carry this part. |
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| profuse007 |
will i need anything else besides the mosfet to get the power turn on?
almost forget, i need to find that TS1.
so, imma log onto mouser.com order some.
btw, do i need to find the specs for the mosfet i have right now or just go ahead and order the z44?
am lookin at the TO-220AB type, whats the specific character to that?
should it matter? all i nkow that it looks similar to mine.
btw, the exisint IRFz34 is 55v and 26A. which z44 is suitable?
digikey.com, is it only sold in bulk? |
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| TO-3 |
| quote: | switchers: IRfz34
________: 2n6487 and 2n6490
^^dont know what it is |
64xx's are bipolar outputs. Don't really have time to input more, right now, but later I will help if others haven't. |
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| EnvisionAudio |
| quote: | | btw, do i need to find the specs for the mosfet i have right now or just go ahead and order the z44? |
From those of us that have extensive car amp repair experience, please just take our word for it. :D
Anyway, the IRFZ44 is what you want. It comes in a TO-220(AB) case and has a metal tab. Don't get the IRFIZ44, which is an insulated tab transistor. They can't dissipate instantaneous heat as well in pulse applications.
IRFZ44 from Mouser
Do you still have TS1? Just reinstall it. |
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| profuse007 |
koo i will order 15 of the IRFZ44(ab) w/ the tab tonite.
anything else i should aware b4 ordering?
what type of resistor is that at the right bottom hand corner?
it has .22ohm +/-5. red red silver---gold
can someone link me to the mouser? |
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| TO-3 |
| quote: | Originally posted by EnvisionAudio
From those of us that have extensive car amp repair experience, please just take our word for it. :D
Anyway, the IRFZ44 is what you want. It comes in a TO-220(AB) case and has a metal tab. Don't get the IRFIZ44, which is an insulated tab transistor. They can't dissipate instantaneous heat as well in pulse applications.
IRFZ44 from Mouser
Do you still have TS1? Just reinstall it. |
| quote: | Originally posted by profuse007
koo i will order 15 of the IRFZ44(ab) w/ the tab tonite.
anything else i should aware b4 ordering?
what type of resistor is that at the right bottom hand corner?
it has .22ohm +/-5. red red silver---gold
can someone link me to the mouser? |
Don't forget that you need to replace all of the gate resistors with 22 ohmers.
http://www.mouser.com/index.cfm?han...roductID=226013
The .22 ohm resistor is 2W.
http://www.mouser.com/?Ne=100&handl...ber%7c%7cSField
This won't look the same, but it is the same thing. |
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| TO-3 |
| quote: | Originally posted by profuse007
for now, i dont care about signals right now, am just looking at the power switch source. what are the things i should be concerning besides replacing the mosfets?
the quote in bold, are you talkin about the physical drivers like subwoofers?
|
Here is a simple main and output section of an amplifier. Q26 and Q27 are the driver transitors. These are in a Darlington Pair with the output transistors. They are called drivers because they are current boosters for the outputs. |
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| profuse007 |
when you say gate resistor, do you mean the resistor on the Gate pin on all of the mosfets?
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| rth |
Yes, he means the gate series resistors between the sg3525 and the FETs, which on my amp are R90-R99. I just happened across this thread while searching google for the 3525 PWM chip since I have a broken PPI 600 watt art series here (PPI-2150AM) that appears to have been made in 1992 according to date codes on parts. My doofus friend had an amp stacked on top of this one, which of course caused thermal failure. Luckily, it appears that the damage is limited to a couple very blown (plastic package melted and soot everwhere) push-pull FETs in the power supply. Everything else visually looks fine. I'm going to replace these 10 fets with some nice low-Rds units from IRF and hopefully that will do the trick. Thank goodness for academic sampling :D
Did you ever get your amp working, profuse? Just curious, it's kinda fun working on these badarse old PPI amps.. I'll get a picture of mine this weekend when I have my camera handy. The board says "752162 Rev K", but I assume we have the same amp.
By the way, for those interested in how amps work, here's a great writeup about switch-mode power supplies:
http://sound.westhost.com/project89.htm
It doesn't show the audio stages but the power supply is half the battle in these 12V amps :scratch1: |
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| sid216 |
| TO-3, do you have a repair shop here in phoenix? if so i have a little work for you... if not, let me know. thanx |
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| TO-3 |
| quote: | Originally posted by sid216
TO-3, do you have a repair shop here in phoenix? if so i have a little work for you... if not, let me know. thanx |
Nope. I just moved here from Colorado 3 weeks ago, and had to leave all of my test equipment and tools there. |
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| sid216 |
| quote: | Originally posted by TO-3
Nope. I just moved here from Colorado 3 weeks ago, and had to leave all of my test equipment and tools there. |
thats a shame... so how do you like phoenix so far? |
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| TO-3 |
| quote: | Originally posted by sid216
thats a shame... so how do you like phoenix so far? |
I lived here for 4 years before. It is still the same just more urban-sprawl. Same with Denver. |
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| rth |
| Hey TO-3, what was the reason that PPI went to 22 ohm resistors instead of the original 468 ohm parts? I don't know if you've seen it but I'm having a problem with the gate drive circuitry of my a600 after putting in new FETs and 22 ohm gate resistors. Please give me some input on that thread if you have any since I'm at a loss as to why the gate driver works fine with no FETs in place but craps out with them installed, even though they should theoretically be easier to drive than irz44n's that seem to be the standard replacement part. Thanks :up: |
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| TO-3 |
| quote: | Originally posted by sid216
TO-3, do you have a repair shop here in phoenix? if so i have a little work for you... if not, let me know. thanx |
What do you need to get fixed? If you have the equipment, I can probably help you out. |
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| TO-3 |
| quote: | Originally posted by rth
Hey TO-3, what was the reason that PPI went to 22 ohm resistors instead of the original 468 ohm parts? I don't know if you've seen it but I'm having a problem with the gate drive circuitry of my a600 after putting in new FETs and 22 ohm gate resistors. Please give me some input on that thread if you have any since I'm at a loss as to why the gate driver works fine with no FETs in place but craps out with them installed, even though they should theoretically be easier to drive than irz44n's that seem to be the standard replacement part. Thanks :up: |
I don't recall any of the gate resisitors being 468 ohms. I know that the previous FETs(don't recall the P/N) had 47ohmers on the gates. 468ohms seems way too high to have on a gate. It is possible that the ground resistor may be inappropriate for the 22ohmer and needs to be replaced with another value. I'll look at one of my boards and get back to you. |
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| rth |
| They might have been 46.8 ohms, I already trashed em so I guess we'll never know. I got the power supply working now, one of the new FETs had its gate shorted to ground already due to high current, which I've now narrowed down to a short in the output stage since the power supply is working great with no rectifiers in there, with +/- 100 volts to boot :D I should've just replaced all these transistors from the beginning since they're 13 years old and have been abused and then some ;) |
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| rth |
Hmm, that should be +/- 50V. :rolleyes:
I'm going to go ahead and replace all these bipolar parts.. are the 2n6487 and 2n6490 parts good enough or is there something better out there? I will, of course, sample them so price is no object :nod: |
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| sid216 |
| quote: | Originally posted by TO-3
What do you need to get fixed? If you have the equipment, I can probably help you out. |
its pretty much the same amp as in this thread, ppi 2150am rev I board. Q47 of the power supply is blown out, the lead next to r28 has fried off the switcher and the trace has lifted a little. i WOULD attemped to fix my self, but i dont feel confident enough to monkey around in this piece of hardware on the simple notion that it is the only one i got (for free) and in its day was a top-o-the line amp and i want to use it, unless i have to drop a ton of cash in to it, for after that ill just buy a new amp.
i have some experiance with electronics (resister networks), i do not have an o-scope(wish i did), i do have a DMM, and many computers, a lot of tools: small screw drivers, soldering irons, mini pliers, bla bla bla.
if this was a crappy little jensen and no problem, no loss, i would dive in and try to fix it my self. not this, i love the old ppi amps and i dont want to mess it up trying to fix it. im the kind of person that would do it once the first time and do it right, with this amp i dont feel im ready to take on some thing this complex, i know i dont have the experence to tackle some thing like this just yet, but im willing to learn, just not on my ppi amp. i do have a crappy little pioneer some were, cant find it though:( so if any thoughts let me know, i appreciate any help. thanx... |
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| TO-3 |
| quote: | Originally posted by rth
They might have been 46.8 ohms, I already trashed em so I guess we'll never know. I got the power supply working now, one of the new FETs had its gate shorted to ground already due to high current, which I've now narrowed down to a short in the output stage since the power supply is working great with no rectifiers in there, with +/- 100 volts to boot :D I should've just replaced all these transistors from the beginning since they're 13 years old and have been abused and then some ;) |
Hey man- I looked at one of my PPIs this morning and found I gave out bad info. The gate resistors are supposed to be 47ohms(NOT 22) and the ground-tying resistor(directly on the outputs of the PWM chip Pins 11 & 14 is 2.2kohms) for the Z44s. Maybe it was the other MosFETs, though I don't recall thier P/N that was 22. Although, if your amp is working now, don't fix it. I apologize to all that may have used the 22s due to my info.
Whenever you replace one switcher, you need to replace them all. This is due to the amount of stress that the part inherits due to the higher amount of power it is subjected to.
Glad your amp is stable now. :) |
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| TO-3 |
| quote: | Originally posted by sid216
its pretty much the same amp as in this thread, ppi 2150am rev I board. Q47 of the power supply is blown out, the lead next to r28 has fried off the switcher and the trace has lifted a little. i WOULD attemped to fix my self, but i dont feel confident enough to monkey around in this piece of hardware on the simple notion that it is the only one i got (for free) and in its day was a top-o-the line amp and i want to use it, unless i have to drop a ton of cash in to it, for after that ill just buy a new amp.
i have some experiance with electronics (resister networks), i do not have an o-scope(wish i did), i do have a DMM, and many computers, a lot of tools: small screw drivers, soldering irons, mini pliers, bla bla bla.
if this was a crappy little jensen and no problem, no loss, i would dive in and try to fix it my self. not this, i love the old ppi amps and i dont want to mess it up trying to fix it. im the kind of person that would do it once the first time and do it right, with this amp i dont feel im ready to take on some thing this complex, i know i dont have the experence to tackle some thing like this just yet, but im willing to learn, just not on my ppi amp. i do have a crappy little pioneer some were, cant find it though:( so if any thoughts let me know, i appreciate any help. thanx... |
It's really not that difficult. I looked in my trunk, I still haven't unloaded it completely, and saw that I have at least one of my sine-wave generators and I think my soldering iron, but my scope and DC power supplies are still in Denver. :mad: I hope to be able to retrieve them later this summer, but I need to work for awhile and get some cash, I was unemployed for a year. My first week in the Valley, I interviewed for a job, and my third week here, I got offered the job. Much better electronic industry here.
If your amp is something you can hold off on for a few months, I can help you out when I do retrieve my test equipment and tools. |
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| sid216 |
| quote: | Originally posted by TO-3
It's really not that difficult.
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well... thats eazy for you to say...:)
| quote: |
I looked in my trunk, I still haven't unloaded it completely, and saw that I have at least one of my sine-wave generators and I think my soldering iron, but my scope and DC power supplies are still in Denver. :mad: I hope to be able to retrieve them later this summer, but I need to work for awhile and get some cash, I was unemployed for a year. My first week in the Valley, I interviewed for a job, and my third week here, I got offered the job. Much better electronic industry here |
well its good you got some of your gear, me personally, i couldn't live with out my computer for more than a few days, and thats with the sound system for it. good luck with the job, i know im going to need it in about 7 weeks. any one want to hire an A+ certifided computer nerd?| quote: |
If your amp is something you can hold off on for a few months, I can help you out when I do retrieve my test equipment and tools. [/B] |
ya, my amp isn't going any where any time soon as with me, so it could wait. besides it will give me some time to work on the design stages of a few projects im tinkering with... |
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| lumanauw |
Ti, TO3,
I've got a strange PPI amp. The amp is PCX1400.
When there is a bass in the system, the toroidal smps core is making sound, like ringing, but quite loud. How to eliminate this? Have to glue all the wires+cores with resin?
PS. The smps driver is SG3525, but there is 2 of HIP4081 full bridge driver. I think the SMPS is not pushpull like ordinary for car amps, but it is full bridge mode, the mosfets are divided to 4 sections. |
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| TO-3 |
| quote: | Originally posted by lumanauw
Ti, TO3,
I've got a strange PPI amp. The amp is PCX1400.
When there is a bass in the system, the toroidal smps core is making sound, like ringing, but quite loud. How to eliminate this? Have to glue all the wires+cores with resin?
PS. The smps driver is SG3525, but there is 2 of HIP4081 full bridge driver. I think the SMPS is not pushpull like ordinary for car amps, but it is full bridge mode, the mosfets are divided to 4 sections. |
I never worked on a PCX amp. They came out after I left PPI. But.... I have experienced that problem with some of the larger Art Series transformers. We used to fix them by putting a lot of epoxy on them. That helps with vibration and suppresses the squeal. |
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| ysr185 |
| I have a PPI amp 2150 that I purchased at a auction , but as soon as i hook it up it blows the fuse on the power line as soon as I turn the radio on. I'll be a bit more specific I hook up the amp then I turn the radio on and the green light on the amp turns on for a split second and then the fuse blows. I tried a higher amperage fuse (assuming the amp might need a bigger fuse) and it does the same thing. Had someone tell me it might be the power supply ? not sure if thats the issue ? has anyone heard on an issue like this on these amps and is the amp worth fixing ? thanks in advance, and any help or comments would be greatly appreciated. |
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| TO-3 |
| quote: | Originally posted by ysr185
I have a PPI amp 2150 that I purchased at a auction , but as soon as i hook it up it blows the fuse on the power line as soon as I turn the radio on. I'll be a bit more specific I hook up the amp then I turn the radio on and the green light on the amp turns on for a split second and then the fuse blows. I tried a higher amperage fuse (assuming the amp might need a bigger fuse) and it does the same thing. Had someone tell me it might be the power supply ? not sure if thats the issue ? has anyone heard on an issue like this on these amps and is the amp worth fixing ? thanks in advance, and any help or comments would be greatly appreciated. |
The PS would be my assumption. Which 2150 model did you get? M, AM, PC? |
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| K-amps |
TO-3,
What's your call on the PC2350? ...overall. |
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| TO-3 |
| quote: | Originally posted by K-amps
TO-3,
What's your call on the PC2350? ...overall. |
Very Nice :up: |
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| K-amps |
| quote: | Originally posted by TO-3
Very Nice :up: |
HeHe Not selling mine anytine soon. :D Back in the day I went through all kinds amps including overhyped RF's... but fell in love with the PC2350. Its rocks!!! |
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| TO-3 |
| quote: | Originally posted by K-amps
HeHe Not selling mine anytine soon. :D Back in the day I went through all kinds amps including overhyped RF's... but fell in love with the PC2350. Its rocks!!! |
Alma Gates used the PC2350s(slightly modded) in her Bronco when she broke the sound records in the mid to late 90s. They will take more of a beating than a red-headed step-child. :headbash: |
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| ysr185 |
the 2150 is a PC series I was hoping to use it but with this problem I'm not sure, I took the bottom cover off and there is nothing that looks burnt or blown. In you opinion is this a good amp ? and should I consider it getting it fixed and keeping it ? also would a reasonable price to pay for replacing a PS on this model if I took it to a car audio shop with a repair tech?
Thanks in advance, |
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| K-amps |
| quote: | Originally posted by TO-3
Alma Gates used the PC2350s(slightly modded) in her Bronco when she broke the sound records in the mid to late 90s. They will take more of a beating than a red-headed step-child. :headbash: |
:) ... Any idea what mods were done? |
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| TO-3 |
| quote: | Originally posted by K-amps
:) ... Any idea what mods were done? |
A couple of windings were added to the trasformer, I think the zeners were replaced with 18V(from 15V), the protection circuitry was adjusted, and they were turned into mono-blocks. Would I recommend these changes?........no. We were always fixing one or two after the shows. |
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| K-amps |
| Ah! The 2350 was not enough as stock! :whazzat: |
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| TO-3 |
| quote: | Originally posted by ysr185
the 2150 is a PC series I was hoping to use it but with this problem I'm not sure, I took the bottom cover off and there is nothing that looks burnt or blown. In you opinion is this a good amp ? and should I consider it getting it fixed and keeping it ? also would a reasonable price to pay for replacing a PS on this model if I took it to a car audio shop with a repair tech?
Thanks in advance, |
That is a good amp. Nice and clean. You can measure the power-supply devices to see if they are shorted. Test for a short from the tab to the outer pins. If they are shorted, all of them need to be replaced. IRFZ44s are easy to find and they should not be too expensive. As for having someone else repair it, in the states, it would be around $60-$80US. If you want, take a picture and post it. |
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| rth |
Replacing the power MOSFETs in the power supply is not hard at all and you just need a $7 soldering iron and a little solder to do it. You can get replacement MOSFETs free by sampling them here:
Fairchild FDP20AN06A0 samples
This is what I did to replace the ones in my ppi a600, which is essentially the grandfather to the pc2150. Ten are required, so get at least that many. They only have 3 legs and they're big so soldering is no problem... you could have another problem downstream that's putting undue strain on the power supply but this is worth a shot since it's cheap to try. :cool: |
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| razirafi |
| Hi: Can someone help me out with the schematics of the PP A600? U7, an integrated circuit on a ceramic board has been damaged because the ceramic board cracked. I plan to repair this by making another circuit board but I don't have the resistor and capacitor values. I emailed PP about this but they replied that the design is proprietary and that they only do servicing of their units in-house. Such a pity, considering that Soundstream Technologies readily gave me a copy of the schematics of their USA204 amp. |
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| TO-3 |
| quote: | Originally posted by razirafi
Hi: Can someone help me out with the schematics of the PP A600? U7, an integrated circuit on a ceramic board has been damaged because the ceramic board cracked. I plan to repair this by making another circuit board but I don't have the resistor and capacitor values. I emailed PP about this but they replied that the design is proprietary and that they only do servicing of their units in-house. Such a pity, considering that Soundstream Technologies readily gave me a copy of the schematics of their USA204 amp. |
There are no schematics for those anyway. The best you can do is try and figure it out by probing the other board, or find a blown amp that still has a good hybrid board that you can replace your bad one with. |
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| justonemoreamp |
| If you need SIP's e-mail me, maybe I can be of help :) |
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| razirafi |
TO-3:
Thank you for the info. Since there is no schematic for this, I'll go about it the DIY way.
lumanauw:
Thank you for the diagram. It sure will help me get started quickly.
justonemoreamp:
I can't send you an email via your email link because my account is still under moderation.
;) :cool: :) |
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| TO-3 |
| quote: | Originally posted by razirafi
TO-3:
Thank you for the info. Since there is no schematic for this, I'll go about it the DIY way.
lumanauw:
Thank you for the diagram. It sure will help me get started quickly.
justonemoreamp:
I can't send you an email via your email link because my account is still under moderation.
;) :cool: :) |
If you cannot fix it, I would definately talk to justonemoreamp. He will be able to help you out. |
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| justonemoreamp |
When does you moderation clear ? I don't want to list my e-mail publicly. If you can wait I have some help for your SIP troubles.
Or I can refer you to others if you like, when we talk in e-mail. I don't want to advertise here on the forum. We got em!
Let me know when you can , or get a mod to send your mail to me. I'll make the rest happen :)
PS thank you TO-3:) :) :) |
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| meepers |
| ooh ooh oooohh you are the PPI GODS???? I have a smoked a300 that I need some help with, most of the parts are smoked too bad to get part numbers off it. I really want to fix it, since I have the matching a404. I can take high res pics of the toasty parts, and help on what else to check would be mucho appreciated |
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| razirafi |
| Hi-res photos would be great but attachments are limited to only about 102kB:cannotbe: ;) |
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| TO-3 |
| quote: | Originally posted by meepers
ooh ooh oooohh you are the PPI GODS???? I have a smoked a300 that I need some help with, most of the parts are smoked too bad to get part numbers off it. I really want to fix it, since I have the matching a404. I can take high res pics of the toasty parts, and help on what else to check would be mucho appreciated |
We can definately help. |
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| twon007 |
| quote: | Originally posted by TO-3
OUCH!!!!! That thing is old!!! When I worked at PPI, I had to fix a couple of those things. A PITA!!!! The thermal sensor should not measure low, so it may still be good. Unless it looks visually cracked. Like I said above, measure the switchers, the MosFETs in the power supply, to see if any of those devices are shorted. |
hey canyou help me out man? got a 2350dm the big boy fan controlled etc... need schematic for it and hard to find parts. |
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| paul_strings |
Hello, I'm brand new here and I can't email people yet, else I wouldn't have bothered everyone publicly about this... I'm looking for a specific part for an old ppi a1200, a U3 driver board I believe it's called. The guy in my town who fixes amps, god bless him, is great at what he does, but not the most creative when it comes to finding obscure parts and stuff. He called PPI and they said they don't make the part anymore, whatever that means, so he threw up his hands and tried to get me to buy some performance technique amp he has in the shop...
I've seen a few posts from people saying they have parts to repair these amps, but as I said, I can't contact people without making a few posts, so if anyone sees this and has that part, please drop me a line!
so in short, HELP! I don't have the scratch to buy a new quality amp for my subs! Don't make me get some pos from auto zone!!:bawling: |
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| impsick |
| quote: | Originally posted by paul_strings
Hello, I'm brand new here and I can't email people yet, else I wouldn't have bothered everyone publicly about this... I'm looking for a specific part for an old ppi a1200, a U3 driver board I believe it's called. The guy in my town who fixes amps, god bless him, is great at what he does, but not the most creative when it comes to finding obscure parts and stuff. He called PPI and they said they don't make the part anymore, whatever that means, so he threw up his hands and tried to get me to buy some performance technique amp he has in the shop...
I've seen a few posts from people saying they have parts to repair these amps, but as I said, I can't contact people without making a few posts, so if anyone sees this and has that part, please drop me a line!
so in short, HELP! I don't have the scratch to buy a new quality amp for my subs! Don't make me get some pos from auto zone!!:bawling: |
So whats the deal with this driver board? why do you need a knew one? Is this thing really not fixable? Im guessing its like one of those boards you find in some Fosgate amps with all the transistors mounted on it? Do you still have this board? Can you put up some pics? If its one of those boards like in the Fosgate amps i talked about, this would be very easy to diy a board, home etch.
Also welcome to DiyAudio. Beware :devilr: You may just loose your girlfriend over this website. :D |
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| paul_strings |
Alright, now we're talking...
Yes, I believe it may be what you mentioned... like a little daughterboard with a few transistors on it... Now, I know next to nothing about electronics, just what I've picked up through osmosis during years of playing music... I've used amplifiers a lot, but don't really understand them. Especially high powered solid state devices like this one... I'm a little more comfortable with old tube amps, but still not really at all useful.
That said, I was led to believe by my friend that was working on it, that the little board does more or less the job of a power tube in the output stage of a tube amp, and those transistors were possibly a couple of fet's. I don't know why the driver board itself can't be fixed, but I was referred to this guy very highly by some people I trust, and can only assume he knows what he is doing when he says he needs to replace it... However I can't see how it could be impossible to fix unless it uses some proprietary IC that's not manufactured anymore, and it doesn't seem like the kind of thing that would be in an amp of this age (the amp is like 15 years old)
I don't have a proper digital camera, but I'll see if I can take the amp apart and recognize the board, and get a useful picture with my camera phone.
And as intriguing as I find the prospect of making a diy replacement, I've never done anything like that before, and I don't know if I trust myself to do it right the first time, especially with such a high power device... I would hate to blow out the transformer, or the power supply that he just fixed...
back in a few... |
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| paul_strings |
| And thanks for the welcome btw... Just from a couple hours of being on here, I know what you mean... It's a good thing my girlfriend is very very patient :) |
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| paul_strings |
Aww crumb... Okay for one thing, I think the guy thought I was dumber than I looked, and the board he showed me was maybe just for size reference, and looks nothing like the thing labeled U3 on the amp, which appears to be some kind of integrated circuit...
Additionally my camera phone isn't cutting it... Maybe tomorow I can borrow a decent camera, until then let's see if these shots do any good... It's a little disorienting because there's a similar looking chip next to it, that has the same number on the back but appears to have a different configuration on the front, and is labeled differently, but here's the front view (it's the one in the forground)
here's the rear view (it's now the one in the bg)
and here's a top view
:confused:
Is this the kind of thing that can be fabricated? I noticed someone earlier in this discussion had a problem with a similar part for an a600 amp and was planning on making a replacement, but I wouldn't know where to start... |
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| Perry Babin |
It looks like you have one transistor missing (bottom right-hand corner). If the board will accept solder, you can replace the missing transistor. If it was defective, the one directly above it has likely failed also.
If you're going to try to solder it, try to get some suggestions from justonemoreamp. He seems to have a lot of experiance with these boards. I've had some that would readily accept new solder and some that would not accept solder no matter what I tried (various iron temps, extra flux, silver bearing solder...).
If you're going to try to reproduce it, you could do so in a program like Cadsoft's Eagle. I was going to do it but I couldn't find a suitable connector to fit the holes in the main board so each connection would have to be made by a tiny piece of wire. That would be OK for a one-off piece but not for something the try to sell to others. The reproduction would probably be easier with through-hole components instead of SMD components.
Someone posted a full schematic for the board here but now I can't find it. Maybe someone else can remember enough about the post to locate it. |
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| lumanauw |
| Very often, if those small boards are not burned or cracked, nothing is wrong with the components (SMD transistor and capacitors). Those boards get malfunctioned just because of aged/cracked solder. Resolder all the solderable points, including the pins that hold the small pcb to the main pcb, and the small boards will work fine again. |
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| impsick |
| paul i have a few of those boards that im not using. But they were taken from a fosgate. I dont know if maybe they are like a standard board that a purchase from the same manufacturer or not. but if you can get a schema of the amp and you email your address i'll send them to you. Maybe they will work? |
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| EnvisionAudio |
| quote: | Originally posted by paul_strings
Aww crumb... Okay for one thing, I think the guy thought I was dumber than I looked, and the board he showed me was maybe just for size reference, and looks nothing like the thing labeled U3 on the amp, which appears to be some kind of integrated circuit...
Additionally my camera phone isn't cutting it... Maybe tomorow I can borrow a decent camera, until then let's see if these shots do any good... It's a little disorienting because there's a similar looking chip next to it, that has the same number on the back but appears to have a different configuration on the front, and is labeled differently, but here's the front view (it's the one in the forground)
:confused:
Is this the kind of thing that can be fabricated? I noticed someone earlier in this discussion had a problem with a similar part for an a600 amp and was planning on making a replacement, but I wouldn't know where to start... |
I know those amps inside and out. There is no need to fabricate anything for those boards and the parts are easily obtainable. The only time you'd need to replace the whole board was if it was cracked. The guy probably doesn't know how to rework those types of boards so he throws up his hands. It's disturbing to know that those kinds of people are "amplifier technicians"...but I know many like this. :rolleyes:
I'm sending you a response email to yours sent to me. I might have those transistors in stock. |
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| EnvisionAudio |
| quote: | Originally posted by impsick
paul i have a few of those boards that im not using. But they were taken from a fosgate. I dont know if maybe they are like a standard board that a purchase from the same manufacturer or not. but if you can get a schema of the amp and you email your address i'll send them to you. Maybe they will work? |
Not even the same amp!! Fosgate is a HexFet output and PPI is Bipolar. |
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| justonemoreamp |
| NOPE ! not the same company, product or design. It won't work lol lol Would not be any better if it did as RF does not stock those old parts either anymore :D :D :D |
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| impsick |
| quote: | Originally posted by justonemoreamp
NOPE ! not the same company, product or design. It won't work lol lol Would not be any better if it did as RF does not stock those old parts either anymore :D :D :D |
i know they aren't the same company. but that doesnt mean a company doesnt make those boards in mass and sell them to other companies to implement into their designs. no? they look alike. same material, and means of mounting to the mother board. and really i dont think i've seen that type of material anywhere else. the pcb on those little boards are like a hard glass type material. i wouldnt be surprised if they were the same.
as a matter of fact looking at the pic closer, im almost tempted to put money on that they are the same boards. I dont know, but something tells me that these two companies probably shop at the same store in China. I'll take some pics tomorrow when i get home.
On the other hand if it were something more like the discrete type of boards that i've seen mounted in the same fashion but in a Lanzar amp i wouldnt have even suggest it.
Oh man, i cant wait to find out. :D and i love the outcome possibilities. im gonna make a fool of myself. HaHa.
EnvisionAudio, so all fogates are hex and all ppi are bi? |
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| justonemoreamp |
| quote: | Originally posted by impsick
i know they aren't the same company. but that doesnt mean a company doesnt make those boards in mass and sell them to other companies to implement into their designs. no? they look alike. same material, and means of mounting to the mother board. and really i dont think i've seen that type of material anywhere else. the pcb on those little boards are like a hard glass type material. i wouldnt be surprised if they were the same.
as a matter of fact looking at the pic closer, im almost tempted to put money on that they are the same boards. I dont know, but something tells me that these two companies probably shop at the same store in China. I'll take some pics tomorrow when i get home.
On the other hand if it were something more like the discrete type of boards that i've seen mounted in the same fashion but in a Lanzar amp i wouldnt have even suggest it.
Oh man, i cant wait to find out. :D and i love the outcome possibilities. im gonna make a fool of myself. HaHa.
EnvisionAudio, so all fogates are hex and all ppi are bi? |
:headbash: :headbash: :headbash: well I got 32 years inside these that says your gonna have fun, but end up empty handed. And Fosgate made Bi-polar way back in their early dazes before the Punch HD line some of their amps used PPI outputs like the Punch 150 PRE HD version. From HD on till now nothing but MosFet outputs
God I feel old now, Good night all .... |
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| impsick |
32 years, i aint got nothin on that. :xeye:
but what do the little boards have to do with output? i mean to me they look like just something for signal conditioning, or eq'n. I dont know though, i sure as hell aint got 32 years in audio, so like i said i'll probably make a fool of myself. i haven't been home yet but i'll get some pics.
on the other hand, those boards, that i have just have some transistors, opamps, and comparators on them. so im confused on what that may have to do with output. unless we are talking about different things. |
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| TO-3 |
| quote: | Originally posted by impsick
32 years, i aint got nothin on that. :xeye:
but what do the little boards have to do with output? i mean to me they look like just something for signal conditioning, or eq'n. I dont know though, i sure as hell aint got 32 years in audio, so like i said i'll probably make a fool of myself. i haven't been home yet but i'll get some pics.
on the other hand, those boards, that i have just have some transistors, opamps, and comparators on them. so im confused on what that may have to do with output. unless we are talking about different things. |
Those hybrid boards are the main amp stage in those amplifiers. The boards have capacitance and resistance designed into the traces so if they blow they are relatively difficult to trace down. Even when I was at PPI we did not stock those boards. |
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| impsick |
| so who makes them? did PPI make them? |
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| justonemoreamp |
I am sure PPI farmed them out to a part manufacturer. Who I have no idea.
Autotek, Rockford Fosgate, Hifonics, PPI, Memphis, and boat load of others all build their amp channel drivers separate and install it to run the drivers and outputs.
So its not a unusual thing to do. In fact it simplifies the manufacturing process, and the in house repair process.
You also need to understand that all these companies built one basic amplifier design, and then Scaled it up or down to suit the buyers need and pocket book.
Remember scaling a amp design simplifies manufacture and streamlines costs so book keepers can count the coin better. Just about everybody, everywhere does this exact same thing. You the consumer never generally will ever see or know anything about this, as most folks are not tech savy to modern manufacturing methods and typical engineering involved with bring a complete product line to market. |
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| EnvisionAudio |
| quote: | Originally posted by impsick
i know they aren't the same company. but that doesnt mean a company doesnt make those boards in mass and sell them to other companies to implement into their designs. no? they look alike. same material, and means of mounting to the mother board. and really i dont think i've seen that type of material anywhere else. the pcb on those little boards are like a hard glass type material. i wouldnt be surprised if they were the same.
EnvisionAudio, so all fogates are hex and all ppi are bi? |
Uhm, that's not what I said. I said that the Rockfords that YOU are referencing and the PPI that WE are talking about are different in nearly every possible way.
That "hard glass material" is alumina ceramic.
| quote: | Originally posted by justonemoreamp
I am sure PPI farmed them out to a part manufacturer. Who I have no idea.
Remember scaling a amp design simplifies manufacture and streamlines costs so book keepers can count the coin better. Just about everybody, everywhere does this exact same thing. You the consumer never generally will ever see or know anything about this, as most folks are not tech savy to modern manufacturing methods and typical engineering involved with bring a complete product line to market. |
Hi Cecil. ;)
I have a good reason to believe that these hybrid devices came from Delco back in the 1980s. Delco was responsible for much of the hybrid cricuitry design then and possessed the laser technology responsible for the film resistors on the boards. My guess is that the links existed between Delco and the automotive industry with the early cross-marketing of aftermarket and factory autosound installations.
It would be most amusing to watch the faces of the general car audio population when amplifier "guts" are laid out in schematics - not just open-bottom pictures. Gee-whiz Mr. Specialized Amp Manufacturer, why are your circuits EXACTLY THE SAME AS the low buck amps?!
Oh, the laughter ensues. |
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| paul_strings |
You know, I've always sort of suspected something like that... There's a belief amongst many purists that the circuits involved in musical instrument amplification were sort of "perfected" in the very early days with vacuum tubes and paper-and-oil capacitors, and that everything since has been a result of incorporating new materials and manufacturing processes in order to streamline production. I can certainy agree that in the realm of electric guitar, tubes are the deal, because part of the sound most guitarists are looking for is created by the unique way in which tubes clip, but for high wattage applications where clean power, headroom and reliability are the most relevant factors, it seem like things have come a long way in the solid state realm, and things like these substrate boards, while they may fail on occasion, in general require far less maintenance than the power stage in an old tube circuit. As I understand it, the main difference in price of production of various solid state car power amplifiers would be the power supply and transformer, and whatever other circuitry is in there like a crossover or bass boost...
So, even just from my rudimentary knowlege of this sort of thing, it would take some pretty serious convincing to get me to buy a brand new power amp in the price range of a zapco or something like that...
I think the main reason I like that old ppi so much is that it is heavy, and has hefty enough fuses, transformer and capacitors to look like it could actually deliver the kind of wattage it claims, as a class ab amp. Plus it was pretty inexpensive to get used, even though it needs a little work... It will still probably be a lot less than I would pay for a new american made amp of comparable power...
Thanks so much for all of your guys' discussion and input, it's been very illuminating! It looks like one of the u3 driver boards IS missing a transistor as was stated earlier, and hopefully will be salvageable, although I don't think I'm gonna try to do it myself just yet :)
This is a great forum, it's inspired me to ask my mom to dig out my dad's old soldering equipment...
respek!
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