Orion 1200D, when I got it it had blown power supply, and 1/2 of all IRF640/9640 in both output wings were dead too. Replaced all parallel FET's, amp played great for like 10 min, after that blew 640's in one wing... Pulled this piece of technology for this wing:
Deadly for FET's part is the left part of the board. Right drives 9640's ok.
And there is no 2 resistors, which is supposed to be the same, that measured the same
(R405-R404 small, R408,409,433,432 big blue)
I understand, that this amp "engineered" this way (everything on these boards are getting extremely hot, to the point that traces on driver and main boards starts peeling), but I guess values of these resistors should be stable for proper driver board operation.
Is it possible to replace these resistors with something more thermally stable, or maybe just go with bigger wattage ones? I guess transistor(s) are leaking on high temps too.
An externally hosted image should be here but it was not working when we last tested it.
Deadly for FET's part is the left part of the board. Right drives 9640's ok.
And there is no 2 resistors, which is supposed to be the same, that measured the same
(R405-R404 small, R408,409,433,432 big blue)I understand, that this amp "engineered" this way (everything on these boards are getting extremely hot, to the point that traces on driver and main boards starts peeling), but I guess values of these resistors should be stable for proper driver board operation.
Is it possible to replace these resistors with something more thermally stable, or maybe just go with bigger wattage ones? I guess transistor(s) are leaking on high temps too.
This appears to be nothing more than a driver board, so the associated low level circuitry that feeds this may also be damaged, and there failure may just be getting amplified through this driver card to the output stage.
So if I were you I would be looking at the drive signals feeding this driver board. And if those signals pass muster, then the driver board may have issues that may be thermally driven into the repeated failure you seeing.
These types of driver cards run very hot to the touch. On Crossfire and Kicker these are usually mounted in such a fashion that there is a strip of thermal transfer material mounted between these transistor and the sink or bottom plate of the amp, just to try and shed the heat somewhere else
I wish I had more info on this Directed/Orion product, but the maker has shown little outside support for its products i.e schematics and such
So if I were you I would be looking at the drive signals feeding this driver board. And if those signals pass muster, then the driver board may have issues that may be thermally driven into the repeated failure you seeing.
These types of driver cards run very hot to the touch. On Crossfire and Kicker these are usually mounted in such a fashion that there is a strip of thermal transfer material mounted between these transistor and the sink or bottom plate of the amp, just to try and shed the heat somewhere else
I wish I had more info on this Directed/Orion product, but the maker has shown little outside support for its products i.e schematics and such
Thank you! I'll check what feeds this boards... it might be the key. I feel, that I am having really hard time trusting something that run as hot as these boards 
However, main board layout was a pleasant surprise for me; it's not like a typical Asian-built amp. All soldering could've been done much better though 
However, main board layout was a pleasant surprise for me; it's not like a typical Asian-built amp. All soldering could've been done much better though You need to look at the gate drive waveforms. The gates of the FETs are driven ~10v from the rail (10vp-p square wave drive signal). The gates of the N-channel FETs are pulled up ~10v from the negative rail. The gates of the p-chanel FETs are pulled down ~10v from the positive rail. The drive signal should be square with little to no rounding on the corners of the waveform.
The zeners are part of a regulator that produces a 12 volt supply. There is one 12v supply per driver board for each rail. To check the voltage on the drivers, measure the DC voltage from the collector of the npn driver to the collector of the pnp driver. It should be ~12v.
When the driver voltage is too high or too low, the FETS can fail. Too low and they won't turn on completely which will make them run hot. If the drive voltage is too high, they FET gates will get popped.
Also check the 1 ohm resistor between the emitters of the driver transistors. Sometimes they open.
If the regulated 12v is OK but the drive signal is weak on the drivers, check the resistors on the collector and emitter of the larger driver transistor.
Of course, you need to check the gate resistors and the transistors on the driver board (this is obvious but I thought I'd mention it).
The zeners are part of a regulator that produces a 12 volt supply. There is one 12v supply per driver board for each rail. To check the voltage on the drivers, measure the DC voltage from the collector of the npn driver to the collector of the pnp driver. It should be ~12v.
When the driver voltage is too high or too low, the FETS can fail. Too low and they won't turn on completely which will make them run hot. If the drive voltage is too high, they FET gates will get popped.
Also check the 1 ohm resistor between the emitters of the driver transistors. Sometimes they open.
If the regulated 12v is OK but the drive signal is weak on the drivers, check the resistors on the collector and emitter of the larger driver transistor.
Of course, you need to check the gate resistors and the transistors on the driver board (this is obvious but I thought I'd mention it).
I'll check everything and post results. 
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