i was hunting down alternator whine on high load, even starter motor can be heard from speakers.
Took rca from amp and right away it blow one of its power supply fet.
What can cause this?
The amp has an isolated secondary and is prone to oscillating when the shield ground is open. When you plug/unplug the RCAs, the shield breaks the ground with the center conductor still connected. This can cause excessive current draw and can cause the FETs or the outputs to fail if the RCAs are plugged/unplugged with the amp on.
ok, everybody now knows this might happened.
I now stop pulling inputs out when amp is on.
cant get schematics to this amp anymore, recommend to check output fets too before changing new irfz44, measured quick its not short circuit but numbers varies from others
I now stop pulling inputs out when amp is on.
cant get schematics to this amp anymore, recommend to check output fets too before changing new irfz44, measured quick its not short circuit but numbers varies from others
Took short course and just changed that blown fet. Amp draws 0.2amps without remote wire, does not lit power on led.
What do you think Perry, what can i do with limited tools available and no schema
What do you think Perry, what can i do with limited tools available and no schema
It would have been better to remove the original, blown FET and leave that slot open. Before you reassemble the amp (after you get it working), you'll have to (at least) replace all if the FETs in that parallel group. You can't have one random FET and expect the amp to be as reliable as possible.
Post the DC voltage on all terminals of the TL494/594. Copy and paste the following into your reply.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
Post the DC voltage on all terminals of the TL494/594. Copy and paste the following into your reply.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
9/10 should be very nearly identical. Re-check them.
What is the DC voltage across the output of the rectifiers?
Post at least one photo of the entire board as the amp is right now.
What is the DC voltage across the output of the rectifiers?
Post at least one photo of the entire board as the amp is right now.
9 and 10 are giving those readings
S: 0.4mv
D: 12.3v (battery is charging)
G: varies between fets, nearest from un-hooked blown one has 11.4v and most far one has 12.1v
S: 0.4mv
D: 12.3v (battery is charging)
G: varies between fets, nearest from un-hooked blown one has 11.4v and most far one has 12.1v
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At the board there is rail voltage measuring points, when meters black wire is on B-, rails are 76mV and 146mV
supposed to be 25V
supposed to be 25V
I think there are other shorted FETs.
With no power applied, what is the resistance gate to source for the power supply FETs. If they're not all the same, list them all.
With no power applied, what is the resistance gate to source for the power supply FETs. If they're not all the same, list them all.
86 87 88ohms on those three on board between gate and source.
fourth resistor which is free now i think was 88.3ohm
between resistor which are hooked up with FETs were 41 42 and third over 60.
fourth resistor which is free now i think was 88.3ohm
between resistor which are hooked up with FETs were 41 42 and third over 60.
Those are all too low.
Remove them and check them out of the board. You can desolder and pull one terminal of the gate resistor and measure them in the board.
Remove them and check them out of the board. You can desolder and pull one terminal of the gate resistor and measure them in the board.
all four fets, tl594 and that fep16 rectifier.
on what order do you recommend to start putting them on board? fets last?
on what order do you recommend to start putting them on board? fets last?
or might there be something else wrong, like if i put new rectifier and tl594 on board, power up and theyre gone right at that moment
I'd prefer to have you check various components/voltages to determine what's wrong with it instead of blindly replacing parts.
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