405-2 blowing up

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26-Jun-2019 11:28 PM

roquad

roquad

Posts: 5

The amp that is not working is a M12565 ver 6, it has a blown FS2, D11, TR10 and the readings across the opamp show between pins 3 and 6 it's open circuit.

N2 also looks suspicious, I have no idea how to test it and the best I could do was compare its resistance readings with the other good N2 network on the good board. Starting with the group of 2 pins I left the probe on the first pin and then took reading of the other pins and discovered the last 2 pins of the group of 3 were: 1.13K and 23.3K, these differed from the readings on the good N2 network that were: 1.32M and 2.75M.

Would a faulty opamp cause all this?

 I would be very grateful for any advice.

 Thanks.

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02-Jul-2019 01:11 AM

Top Cap

Top Cap

Posts: 2

I have similar problem but getting hold of replacement N1 and N2 is difficult. The same reason I do not like programmable devices in modern electronics, if it fails then you are basically stuffed. As a Plan B I have engineered the circuit onto a small piece of proto board, just hope 2N3904 and 2N3906 will work OK. I cannot see how I can put the drawings on here which is a shame and not sure if links to my website for download will be acceptable to Dada so will not risk it. I tried to do this on Vinyl Engine to help someone and I was banned, sad really as I do this for a hobby and my crime was trying to help someone.
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