Zapco Z-2KD Amplifier

[Perry Babin]

Can you post a much higher resolution, clearly focused photo of the driver board alone (tightly cropped)?

 

[Goldie89]

Best I can do it appears to be a 3S board.

 

[Perry Babin]

Remove all of the outputs that are being driven by that side of the driver board and reinstall Q7 and Q11. Do you still have r-r oscillation on the other bank?

Is R13 within tolerance? Have you confirmed that the other resistors in that area of the driver board are within tolerance.

Are Q7 and 11 new?

 

[Goldie89]

I bumped up against one of the output inductors and noticed all outputs are doing what’s pictured. Yes Q7 & 11 are new and R13 reads 999ohms. It will take me sometime to remove all the outputs.

 

[Goldie89]

Now amp plays fine and has full rail voltage the inductor was L3 that must has a short somewhere in it.

 

[Goldie89]

Picture of outputs oscillation

 

[Perry Babin]

It takes just a few seconds to remove each output. Apply enough solder to all legs to allow the iron's tip heat all 3 at once. The FETs will literally fall out. Then desolder. That will take virtually no time it you have a good desoldering pump like the Edsyn DS017.
The Original Deluxe SOLDAPULLT: EDSYN Inc.

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