If the opamps are in sockets, remove them all and test again for supply shorts. if no shorts, start installing them one by one testing for shorts again.
been a while since I looked at that design, but standard troubleshooting procedures, isolate, method of elimination, etc
yes pics are always good for review.
been a while since I looked at that design, but standard troubleshooting procedures, isolate, method of elimination, etc
yes pics are always good for review.
I first want to thank all of you who are helping me to find a way to repair this.
Then I tried several op amps with the same results.
I then tried with a single op amp to measure every socket here are the results:
A1R: 16,8. A1L 8,8.
A2R: 6,8 A2L 6
A3R 6,80 A3L 6,57
A4R 6,73 A4L 6,88
A5R 7,31 A5L 6,88
A6 6,8
A7R 6,8 A7L 6,79
A8R 6,9 A8L 6,95
With some op amps I only getting 8 v on A1R instead of 16,8 with the reference one
Then I tried several op amps with the same results.
I then tried with a single op amp to measure every socket here are the results:
A1R: 16,8. A1L 8,8.
A2R: 6,8 A2L 6
A3R 6,80 A3L 6,57
A4R 6,73 A4L 6,88
A5R 7,31 A5L 6,88
A6 6,8
A7R 6,8 A7L 6,79
A8R 6,9 A8L 6,95
With some op amps I only getting 8 v on A1R instead of 16,8 with the reference one
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It sounds like you have gotten the power supply reversed to the op amps at some point and have blown them and now they are shorted.
Your next step should be to verify the voltage between pin 4 and pin 8 on the op amp sockets with no op amps installed. With the negative lead in pin 4 and positive in pin 8 you should have around 34-36V present and the meter should be showing a positive measurement.
Your next step should be to verify the voltage between pin 4 and pin 8 on the op amp sockets with no op amps installed. With the negative lead in pin 4 and positive in pin 8 you should have around 34-36V present and the meter should be showing a positive measurement.
This is starting to make sense. it sounds like you have an open power trace on the board. Any op amp that gets plugged into either of those two sockets would be damaged and shorted.
With the power off measure the resistance between pin 8 on A2L and A3L, then do the same between pin 4 on A2L and A3L. That should tell you which trace is open.
With the power off measure the resistance between pin 8 on A2L and A3L, then do the same between pin 4 on A2L and A3L. That should tell you which trace is open.
I get ,2 ohm between pin 8 on A2L and A3L and no resistance between pin 4.
Flip the board over and measure resistance between pin 4 of A2L and the capacitor beside it to see if they are connected. If not there is a break in that trace. If they are connected there is a break in the trace between the cap and A3L.
Once you figure out which trace is broken have a close look at it and see if you can see where it is. If there's a burn somewhere something shorted and overloaded it. If you see a tiny scratch or crack it was likely a manufacturing defect. Sometimes the trace is eroded away during etching too leaving a round hole though it, the solder mask does a great job of hiding it. Either can be repaired, but it would be wise to throw out any op amp that may have been plugged into those sockets.
Once you figure out which trace is broken have a close look at it and see if you can see where it is. If there's a burn somewhere something shorted and overloaded it. If you see a tiny scratch or crack it was likely a manufacturing defect. Sometimes the trace is eroded away during etching too leaving a round hole though it, the solder mask does a great job of hiding it. Either can be repaired, but it would be wise to throw out any op amp that may have been plugged into those sockets.