Joel, sorry for coming back so late. Yesterday a strong cold hit me and gave me my first wish for the new year.
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Your next steps could be
- check some voltages at the output of IC408. One of the pins B1...B8 should have 5 V and all the other less voltage. Which Bx depends on the selected BPF.
- check voltage at pin 9 of IC402 and voltage at pin 9 and pin 7 of IC403. All should have 2.5 V.
- check voltage at pin Y0 ... Y3 of IC402. One of the pins should have 2.5 V and all the other less voltage. Which Yx depends on the selected BPF.
Probe at solder pads connected to these pins, e.g. solder pad to L401, L403, ..., T401 and so on.
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Wish you HNY.
73 Ludwig
