PPI amp (power precision) blew out

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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.
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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.
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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
 
Hold on...

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:
 
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.
 
profuse007 said:
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.


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.

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.
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 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.
 
profuse007 said:
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?
 
I repair these amps...

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
 
The voltages on the mosfets.

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
 
profuse007 said:
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?
 
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?
 
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 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.
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)
 
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.


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.
 
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?
 
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.
 
EnvisionAudio said:


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.


profuse007 said:
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?handler=cart._displaycart&&LstDispProductID=226013

The .22 ohm resistor is 2W.

http://www.mouser.com/?Ne=100&handl...+2W&crc=false&N=125&Ns=MfgrPartNumber||SField

This won't look the same, but it is the same thing.
 
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