Orion 2150SX

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I am lost
I replaced ALL capacitors , all the powersupply transistors , the 2 sets of a06 and a56 that will typically go out in the power supply , I tested all the 2n6488 and the 2n6491's and only 2 2n6488 transistirs were bad on 1 channel but i replaced all 5 with same 2n6488, I rechcecked my work turned on the amp with a 12volt powersupply but low amperage it played great no problems on either channel , gain worked fine , eq button worked , mono worked , all was fine so i set it aside, I got 2 other 2150sx's and rebuilt the powersupplys in the aswell they turned on played music just fine all was great BUT when hooked up to a car or standard powersupply with higher amperage they fried 1 bank of powersupply transistors went up in smoke , there were no traces burnt or crossed , now in the powersupply on 1 side there is an L7815CV and a 2n6488 they checked out fine so i did not replace those and even after a sedcond powersupply failure they still check ok , anyone have any ideas what i missed ? this was quite an expensive lesson to learn , but atleast hopefully I will learn what I did wrong.

thank you in advance
redblaze
 
would the amp actually work and turn on and play if 1 was shorted out in the audio or powersupply section ? they are the green caps correct? , or the small round orange ones ? also I tone them to see if they are shorted should I do that or try to get an actual reading ? at the base of the large torroid there are 2 small orange circular caps they tone as shorted , but on all 3 amps they act the same , maybe this is the problem ? there is 1 green cap in the powersupply on 1 that reads as shorted and all the rest seem fine in the same spot on the other 2 amps . any special way I should check these? I have never checked them before :( probably a good idea to learn how before I blow up another 1 :(

thank you
redblaze
 
Did you check the 10 ohm resistors between the collector of the MPSA56 PS driver transistor and ground? They often open and won't allow the driver to turn the bank of FETs off.

Also check the 12v zener connected between the gate drive and ground. It's located between the gate resistors for the power supply. If it's shorted, only half of the transformer will be driven which can cause power supply failure.

Did you check each of the power supply FET gate resistors?

If you have a scope, check the drive signal on each of the power supply FET gates. They should be essentially the same for both banks of power supply FETs. The signal should be square (not significantly sloped) and should go to ground. It will only be ~4v in amplitude at idle.

The tantalum caps are the orange, epoxy coated capacitors.

The green epoxy coated caps are mylar/polyester capacitors. None should read 0 ohms. If it does, it needs to be pulled and checked. If it's in parallel with a larger capacitor, the meter may read near zero ohms but as the larger capacitor charges (due to the voltage applied by the meter), it should eventually indicate that it's open.
 
Ok some of the gate resistors read 4.3 to 10.3ohms that is with bad transistors still soldered in place I will change those , most of the zener diodes read .3 and tone as if they are shorted on the MM only a few wont give a tone , on what appears to be all metal zener diodes a couple read 4.3 and 1 read 99.5, the orange coated round caps by the torroid read .3 and tone, the meter doesnt flucuate as if its charging the caps, on the audio side the 2 round orange caps at the end of the 8 1000uf caps tone aswell but read 25.4 and they are marked 1kv on top 101k below that, another strange thing I noticed on 2 of the amps there is a large zener between the small first torroid and the 2 smaller 1000uf caps in the powersupply and the power wire attatches before those 2 caps , but on 1 2150 there is no large zener between the caps and torroid but that is where the power wire is attached and in that amp nothing was removed prior to me working on it so it appears to be factory done. unfortunately I do not have a scope so I cannot check the wave forms. the 2150 I am working on first is also the 1 that is on ampguts http://ampguts.realmofexcursion.com/ just for reference, on that amp i replaced all caps except for all the 1000UF , green or orange caps and the 3300UF they seemed to be fine except for the green and orange which I never checked :( , but now the 3300UF are reading .3 and not flucuating the MM just giving a constant tone , I will pull them all and recheck
I also replaced ALL of the powersupply transistors. and the a06 and a56 in the powersupply.

thank you
redblaze
 
ok I pulled all of the powersupply transistors and 3 checked bad , all of the gate resistors show fine at 10.3 - 10.4 ohms on each side there is a 100ohm resisotor and they check fine , I pulled 1 end of the zener dioded off the board and checked those they gave no reading which I believe is ok right ? so atleast I know they arent shorted ? when I checked the 3300UF caps they showed shorted and so did the smaller 1000UF caps in the powersupply when I removed the 3300UF caps they checked fine out of the board BUT the contacts where they were soldered showed shorted so I pulled the smaller 1000UF caps and the spots where the 3300UF caps were at were no longer shorting out so I replaced the 1000UF caps with new ones and the spots where the 3300UF caps were was still ok and then I put the old 1000UF caps back in and it still showed ok so I am confused again 1 second the caps show shorted in the board and then out they are ok then when back in they are ok , on the audio side all caps made the MM jump through the numbers , the green caps only a few made the MM jump through numbers the rest gave no reading at all , and the orange round caps only the 2 at the beginning of the 8 larger caps show 25.6 the rest give no readings aswell as the small oblong bright orange caps they give no readings. ok so far thats where I am at , I have checked all the output transistors but I am going to pull them and check them off board. but does any of this maybe clear something up or pinpoint anything ?, I am lost , you think you have it then boom something messes you all up and you have to start over I just cant believe they played for over an hour, each amp no problems no overheating hooked up to 2 15's but just on a low amperage power supply , I figured after an hour they would show some signs of a problem the 10amp fuses I used for testing them to trun on didnt even blow but the second they are on a car battery flash fire in the powersupply :( .

thanks again
redblaze
 
If the caps were shorted, you shouldn't have reinstalled them. The problem could be intermittant and can cause problems later.

Was the amp mounted to the vehicle (or touching a grounded surface) when it blew the supply?

It's rare that only a few FETs fail in the supply. Even if the others appear to be OK, they could be damaged. It's best to replace all FETs at once. At the very least, you should pull all of them and check them out of the board. With your meter set to ohms, there should be absolutely no continuity between the gate and either of the other terminals.

The zener diodes should behave just like a normal diode when checking them.
 
No the amp wasnt mounted and was not grounding out, I only put the old caps back in to see if something else was causing the shorting or if it was the caps because the old caps checked fine out of the board so I only put them back in to see if they behaved like the brand new ones and they did but I have removed them.

I did check the transistors out of the board I removed them all and checked each 1 individially I get .502 to .508 on each 1 after checking with ground on the middle leg and pos on the right leg, all these transistors were brand new I installed them and checked them before install untill the big blowup , and only 3 are completely shorted, I am going to buy all new agin though.

I have found a few diodes that are acting up they gave me readings all over the place in both directions but when I pulled them from the board they seem fine only readiing in 1 direction , there are also full metal diodes that did the same thing once pulled from the board they read in only 1 direction, now does that mean that there is something still in the board not allowing them to close and that is what is supposed to happen or are they supposed to show voltage in 1 direction even when installed ? so far I dont believe I have found a zener diode they are all reading in 1 direction and I have measured the voltage drop and they are all around the same .533 to .544 except for the full metal ones are in the .705 to .710 , now a zener will measure no matter if pos is on the anode or cathode correct ?
only when the few diodes I mentioned are connected do they read in both directions and they flucuate in voltage readings. other than that so far all diodes are showing reading in 1 direction.

do i check the A06 and A56 the same way as as the other transistors ? and if there is no direct short what should the readings be close to ?
all the parts I have pulled from the board I have not reinstalled nor installed new yet I only put new caps in for a few to see if the short was still there.

redblaze
 
I have found a few diodes that are acting up they gave me readings all over the place in both directions but when I pulled them from the board they seem fine only readiing in 1 direction , there are also full metal diodes that did the same thing once pulled from the board they read in only 1 direction, now does that mean that there is something still in the board not allowing them to close

**** The diodes don't open/close. When the forward breakdown voltage is reached (~0.6v), the diode begins to conduct.



and that is what is supposed to happen or are they supposed to show voltage in 1 direction even when installed ?

**** The rest of the circuit is influencing the readings. If the circuit doesn't prevent the meter from reaching the diode's breakdown voltage, it will read ~0.6v when forward biased. It's more difficult to get an open reading when the leads are reversed because virtually anything in the circuit can prevent the meter from reaching the 2+v required for it to read open (for a fluke meter in diode check mode).



so far I dont believe I have found a zener diode they are all reading in 1 direction and I have measured the voltage drop and they are all around the same .533 to .544 except for the full

**** These are likely standard rectifier diodes.



metal ones are in the .705 to .710 ,

**** These are not likely metal. Some diodes use a gray plastic case.


now a zener will measure no matter if pos is on the anode or cathode correct ?

**** Not unless you have a meter that applies enough voltage to cause the zener to break down when reverse biased. Most meters apply less than 3v to the diodes in diode check mode so the zener will read ~0.7v in one direction and open in the other direction.


only when the few diodes I mentioned are connected do they read in both directions and they flucuate in voltage readings. other than that so far all diodes are showing reading in 1 direction.

**** No diode (when out of the board) should pass current in both directions. If it does, it's defective.



do i check the A06 and A56 the same way as as the other transistors ?

**** It depends on 'the other transistors'.



and if there is no direct short what should the readings be close to ?

**** Out of the board, the A06/56 should be open between the outer legs no matter the placement of the leads. They should read ~0.6v from the center leg to the outer legs. The A56 should give those readings when the black lead is on the center leg. The A06 should give those readings when the red lead is on the center leg.
 
I pulled all the a06 and a56 and all checked ok , I also pulled every 2n6488 and 2n6491 and they checked ok, only parts left to check ar the the 337T and 317T can you tell me what readings I am supposed to get on those , they are the 2 transitors or rectifiers at the beginning of each bank of 2n6488 and 2n6491 , I also have to check the L7815 and I am not sure what reading that should give aswell. then there is the on the underside of the baord the 2 big rectifiers but they check ok and then what looks to be a thermal protection part wrapped in plastic can that cause the amp to fail and burn parts and what is that supposed to give a reading of , because short of unsoldering the rail caps and all the resisitos , op amp ther isnt much left on the board and I havent found 1 other bad part except the 3 powersupply transistors that were brand new and checked ok before I put them in, oh I also am going to check the u07 and u57 gate transistors .


thanks
redblaze
 
ok upon further examination of the amp and reading other posts about the 2150SX and looking at pics I noticed the 100UF cap by the remote was in backwards so I am going to check it and repalce it, can this still let the amp trun on and play ? and when installed on a car battery cause powersupply transitors to fail ? please read previous post aswell if this wont cause much of a problem.

thank you
redblaze
 
I have 1 more ? I have always known these orion 2150SX amps NOT to be 2ohm mono stable you can only run them at 4ohms mono correct ? there is a guy at a stereo shop consistently hooking up his 2150SX to 1 4ohm sub and all of us who have installed stereo equipment know that when you bridge an amp it sees half the ohm load of the speaker so a 4ohm speaker bridged mono on a 2150SX sees a 2ohm mono load but this 2150SX keeps playing. so are they 2ohm stable? have I been wrong all these years ?
 
only parts left to check ar the the 337T and 317T can you tell me what readings I am supposed to get on those , they are the 2 transitors or rectifiers at the beginning of each bank of 2n6488 and 2n6491 ,

**** With the amp powered up, you should have ~±16v on the op-amp power pins. If you have that, the 317/337 are OK. They are voltage regulators. They are internally protected so they very rarely fail.

I also have to check the L7815 and I am not sure what reading that should give aswell.

**** If it's not shorted, it's likely OK. This is also internally protected and unlikely to fail.

and then what looks to be a thermal protection part wrapped in plastic can that cause the amp to fail and burn parts and what is that supposed to give a reading of ,

**** That's a thermal switch. It opens when the amp gets too hot. This breaks the power connection to the 494 and the amp shuts down.

because short of unsoldering the rail caps

**** I've seen the rail caps in these amps fail. When they fail, they generally short which can cause the power supply to fail. That's not likely your problem since the amp powers up on the bench.

and all the resisitos , op amp ther isnt much left on the board and I havent found 1 other bad part except the 3 powersupply transistors that were brand new and checked ok before I put them in, oh I also am going to check the u07 and u57 gate transistors .

**** If the audio section is producing clean audio, the U07/57 driver transistors are likely OK.


**** The 100uf cap should be replaced if it was installed backwards.

**** The amp is not 2 ohm mono stable. If one is being driven into a 2 ohm mono load and is surviving, the owner is lucky.

**** When the transistors are clamped in the heatsink, you need to check for continuity between the heatsink and the tabs of all of the heatsink mounted components. With the exception of one rectifier, there should be no component that has anything near 0 ohm continuity between its tab and the sink.
 
ok I have completely rebuilt the powersupply from the a56-a06's to the transistors , I replaced the 1000UF caps in the powersupply with new , the 3300UF are ok , I replaced the 7815 and 2n6488, and the 100UF that was backwards with a new 1 aswell , I put the 317 and 337 regulators back in but left out ALL of the 2n6491 and 2n6488 just to power it up , it comes on and does not blow the 25 amp fuse i have in line but the large torroid makes a hissing sound and the right side 317 and 337 regulators start to get very hot so I shut it down quickly but it is powering up again, I checked the voltage on the regulators and I am getting on the center pin of the 317 I believe I may have it backwards ( my figures not the regulators ) but the 317 is giving 13VDC and the 337 middle pin is giving -35VDC but only the right side or yellow speaker lead side is getting hot the orange side gets warm but when I had it working before they all 4 just got warm not hot like the yellow side , all 4 regulators are giving the same VDC readings and on the op amp its reading 13VDC on the power pins aswell ( 13 volts instead of 16VDC like you said due to my powersupply I believe) and it is not shorting between the heatsink and transistors and i have no solder bridges all clean solders I checked those aswell.

redblaze
 
The 317 should have positive rail on pin 3. If it doesn't, check the voltage across the 5.6 ohm resistor that feeds it. If the voltage is higher across that resistor than it is on the 5.6 ohm resistor that feeds the 337 next to it, there may be an excessive load on the regulator. Check the value of the resistor with the power off (preferably with one leg desoldered from the board) to make sure it's within tolerance. If there is an excessive load on the regulator, it could be a defective op-amp or leaking (leaking electrically) capacitor.

The regulators are isolated from each other so unless the positive rail voltage is low, there's no reason for the input/output voltage to be low on both positive regulators.
 
I checked acroos all the voltages on the regulators and they read as yellow side , side that gets hot fast

317 leg 1: 12.50 337 leg 1: -12.65

Middle leg : 13.75 Middle leg : -35.55

leg 3: 35.41 leg 3: -13.90


readings on the orange side are

317 leg 1: 12.45 337 leg 1: -12.81

Middle leg: 13.70 Middle leg: -35.18

leg 3: 35.07 leg 3: -14.07

these readings are with it powered on and the voltages across the 5.6 ohm resisotrs 317 .34VDC 337 .31VDC now on the orange side there are diodes in the places where the 5.6 ohm resistors are on the yellow side and on both of those I get exact readings accross the diodes at .68VDC
also these readings are with all the transistors now in place the 2n6488 and 2n6491's , it still powers up ok and doesnt blow the fuse but I do not leave it on but for a few seconds for testing because the regulators on the yellow channel get hot fast and still not shorting between heatsink and transistors and hissing still coming from torroid.

thanks
redblaze
 
The regulators are all working properly. These regs work to produce a 1.25v drop across the resistor that's connected between the output and the adj terminals. All of these have a 1.25v difference between those terminals.

What is the voltage on pins 4 and 7 of the 5534?

There are two 2.7 ohm resistors feeding the power supply terminals of the 5534 (near the regs with the 5.6 ohm resistors). What's the voltage across those resistors?

If you clamp those regs to the heatsink (only one or two screws would be needed), you can work for longer periods without the regs overheating.
 
ok hoping I measured correctly on 5534 pin 4 is - .68 to -.69 leaving the ground to the MM on ground and pos on pin4 I get those 2 readings. on pin 7 done the same way i get -.024 and this is for both 5534 on the resistors I get on 1 -13VDC and on the other +13VDC and this is also for both resistors by the 5534 and the resistors i tested were 3.3 ohms each. below I will indicate the pins I tested on the 5534. and readings i get on all pins. its the same for both 5534.


.11V .13V .-.04V .-.68V

.11V .-.02V .-.02V .-13V
 
Something isn't right. If the resistors are near 3 ohms and have 13 volts across them, they would burn. When you measure the voltage across them, you would have one lead on each end of the resistor.

If you had your meter's ground lead on the same ground you used when you measured the voltage on the regs, the resistors are likely open. If this is the case, it's likely a defective op-amp. It's unlikely (but not impossible) to have two capacitors short and cause both resistors to open. The op-amp should be the only device that's connected across the outputs of both regulators..

Attached is the pin-out for the 5534.
 

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