there is a via on bottom side of board that is pulled? how would that make them read shorted? i can try to repair it with my conductive pen
Don't use a conductive pen. Use wire if necessary. Conductive pens are better suited for logic circuits.
Did you check the ones on the other side of the amp?
IF you have an open connection to the gate leg, the gates can charge and make the FETs appear to be shorted.
Did the short go away when you removed the FET?
Did you check the ones on the other side of the amp?
IF you have an open connection to the gate leg, the gates can charge and make the FETs appear to be shorted.
Did the short go away when you removed the FET?
If there is no short with the FETs out of the board, it seems to indicate that the connection to the gate of the FETs is open (allowing the gates to remain charged and causing the FETs to appear shorted.
Reinstall them and do whatever you did to make them appear shorted. Confirm that they again appear shorted. Remove power from the amp and connect a jumper from the gate to the source leg of one of the FETs. Does that cause them to read OK in the board?
Don't apply power with the jumper in place.
Reinstall them and do whatever you did to make them appear shorted. Confirm that they again appear shorted. Remove power from the amp and connect a jumper from the gate to the source leg of one of the FETs. Does that cause them to read OK in the board?
Don't apply power with the jumper in place.
Ok got the protect issue solved , It seemed to be one of the vias, It will power up fine with green light but no audio is present when i put a signal on it, the outputs are new and checked good in circuit
Are you getting audio to any of the pins of the driver board?
Do you have rail-rail oscillation on the output transistors?
Do you have rail-rail oscillation on the output transistors?
I think that there were at least two versions of this amp. I don't know which one you have. If it uses only IRF640s for the outputs, the oscillation will be on the center leg of half of the outputs and on the 1st and 3rd legs of the other half of the outputs.
Post a photo of the audio driver board in your amp.
Post a photo of the audio driver board in your amp.
I assumed that you reinstalled the driver board but I didn't confirm it. If it's not installed, you won't get rail-rail oscillation on the outputs but that shouldn't prevent you from getting audio on at least one pin of the driver board.
Do you have positive and negative rail voltage?
Do you have both positive and negative regulated voltage on the power supply pins of the op-amps in the preamp section?
Do you have positive and negative rail voltage?
Do you have both positive and negative regulated voltage on the power supply pins of the op-amps in the preamp section?
positive and negative voltage present on all outputs all op-amps have positive and neg regulated voltage except for ic101 its in front of rca jacks
Are you sure that you checked the right pins on IC101?
Are you sure that it's installed correctly (not turned 180°)?
Are you sure that it's installed correctly (not turned 180°)?
If none of the op-amps have any significant voltage on their output pins (1 and 7 for 8-pin op-amps), you need to drive a signal into the amp and find where the signal is lost.
i get signal on output pins 1 and 7 on the following op-amps ic101 , ic102 , ic103, ic105, ic106 , ic107 has signal on pin 1 but not on pin 7 , ic110 no signal either pin trace looks staticy
Please re-read (very carefully) the 'Best Initial Settings' section on the oscilloscope page of the site (page 73), read down to the 7 questions and make sure that you can answer them.
When you list the timebase setting as 1 that doesn't tell us anything. It could be 1ms, 1us, or even 1s.
After reading the Best Initial setting and setting the scope as suggested there, post another photo with the waveforms on all 3 legs of Q210. Set the vertical amp to 20v/div. Set the timebase to 2ms.
When you list the timebase setting as 1 that doesn't tell us anything. It could be 1ms, 1us, or even 1s.
After reading the Best Initial setting and setting the scope as suggested there, post another photo with the waveforms on all 3 legs of Q210. Set the vertical amp to 20v/div. Set the timebase to 2ms.
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