That seems a bit low. It's generally about 15v in the larger amps and I don't see a reason for it to be less in the smaller amps. Is the DC voltage feeding the amp at least 12v?
Yes but be careful. If the FETs were overheating at idle, there may be a problem with the drive circuit.
With no limiter 12.09v,FETs still heat up.The curve on the wave form might be a sign of a bad inductor?
For the FETs that are heating up...
How long does it take for the FETs to get too hot to hold you hand on them?
Is there any DC offset on the output?
Do you have a load connected?
Measuring with the black probe on leg 3 and the red on leg 1, what is the DC voltage measured on the high and low side FETs?
I think you may need to calibrate your probe (not critical, just a note).
The curved part at the top of the waveform that extends above the positive rail is drive voltage. The rising side is curved because the gate capacitance is being charged through the gate resistance. The falling side of the drive signal is more vertical because there is essentially no resistance in the discharging of the gate capacitance.
How long does it take for the FETs to get too hot to hold you hand on them?
Is there any DC offset on the output?
Do you have a load connected?
Measuring with the black probe on leg 3 and the red on leg 1, what is the DC voltage measured on the high and low side FETs?
I think you may need to calibrate your probe (not critical, just a note).
The curved part at the top of the waveform that extends above the positive rail is drive voltage. The rising side is curved because the gate capacitance is being charged through the gate resistance. The falling side of the drive signal is more vertical because there is essentially no resistance in the discharging of the gate capacitance.
After about 15 seconds FETs will be to hot to touch.
No DC offset on the outputs and no load connected.
High side 3.655v
Low side 3.342v
The last to digits of each voltages keep going up slowly.The board is out of the sink so i could not wait for them settle.
No DC offset on the outputs and no load connected.
High side 3.655v
Low side 3.342v
The last to digits of each voltages keep going up slowly.The board is out of the sink so i could not wait for them settle.
Yes IRFB32N20D
I got them from an authorize distributor.I also repair two order amps with FETs from that same batch.I will install the rest of FETs that survived to make sure.
Also the 100v/220uf caps on the output if they are bad can i get results like this?
I got them from an authorize distributor.I also repair two order amps with FETs from that same batch.I will install the rest of FETs that survived to make sure.
Also the 100v/220uf caps on the output if they are bad can i get results like this?
I'd suggest repairing all known problems before you do anything else regarding the overheating outputs.
I went back to this amp toady and now it has more problems.
With the high side FETs in circuit it will cycle power and protect.When i remove them it will power up.
Other problem before that was the high side FETs would heat up at idle even after i tried a next driver board.
With the high side FETs in circuit it will cycle power and protect.When i remove them it will power up.
Other problem before that was the high side FETs would heat up at idle even after i tried a next driver board.
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