Seems this amp may be different than I expected. Its using IRF640N for output fets and there is no HIP4080 to be found. There were no PS fets in the amp but 47ohm gate resistors. Nice square wave on all gates.
I put an IRF3205 into each of the 4 quadrants of the PS, not sure if those are OK for this amp though but those are the best PS fets I've got (I mainly don't want to work on Class D).
The amp is missing one output FET. Also there was a bag of Fat clips inside the amp. Definitely messed with before.
Amp tries to power on for 1 second and then goes into protect. I cannot find any issue with any of the outputs nor output drivers. Briefly, I see about 120v rail for that 1 second, and then the voltage drops slowly. I see about +-13VDC on the opamps also briefly.
I'm just not knowing how to work on this being Class D and its been awhile; that and I'm confused because I thought this amp would have a HIP4080 and totally different fets.
Any clues as to why it might be going into protect?
I put an IRF3205 into each of the 4 quadrants of the PS, not sure if those are OK for this amp though but those are the best PS fets I've got (I mainly don't want to work on Class D).
The amp is missing one output FET. Also there was a bag of Fat clips inside the amp. Definitely messed with before.
Amp tries to power on for 1 second and then goes into protect. I cannot find any issue with any of the outputs nor output drivers. Briefly, I see about 120v rail for that 1 second, and then the voltage drops slowly. I see about +-13VDC on the opamps also briefly.
I'm just not knowing how to work on this being Class D and its been awhile; that and I'm confused because I thought this amp would have a HIP4080 and totally different fets.
Any clues as to why it might be going into protect?
There are 2 1D transistors on the audio driverboard that go bad and cause these amps to protect .
Pull the audio driverboard and see if the amp will power up
Pull the audio driverboard and see if the amp will power up
If you have the tutorial, refer to the Class D type 7 to get familiarized with this type of amp.
There are two amps with the same model #. One has the 11 pin driver board. The other the 4080.
There are two amps with the same model #. One has the 11 pin driver board. The other the 4080.
Thanks guys, definitely have at least 1 bad diode on the driver board.
I need to order parts including diodes and IRFx640.
QQ - IRF640N - Are those a decent fit for amp repairs? I know 540N has issues in some amps but could not recall about 640N. They're just a better price on Arrow.
I need to order parts including diodes and IRFx640.
QQ - IRF640N - Are those a decent fit for amp repairs? I know 540N has issues in some amps but could not recall about 640N. They're just a better price on Arrow.
Those FETs work for the amp that used them originally. In virtually all cases, it's best to use the exact replacement. The main exception to this rule is the IRF3710 where the original part generally won't work but the IRF3710Z will.
OK so the non-N were in this amp. I've ordered non-N from TTI who also had the 9640 at a decent enough price as well. Vishay brand.
Aw shoot made a mistake. I got confused and ordered too quickly then. This amp has 640N fets in the outputs. I hope the regular IRF640 will work. I just ordered 200. I think it'll be fine going in that direction (N to Non-N) but not the other way around.