QUAD 606: R41 and R3. Mixed up on both M12910 - Issue 1 PCBs.

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11-Nov-2019 10:21 PM

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Posts: 13


FYI and comments if you want:

I found a nice one on a QUAD 606. Maybe the below was already posted earlier?

* Schematic: R3 = 5.6kOhm / 500mW and R41 = 10kOhm / 250mW.

* Mounted on both the M12910 - Issue 1 PCBs: R3 = 10kOhm / 250mW and R41 = 5.6kOhm / 500mW.

Did the amp fail due to this? Errr... not necessarily. The amp ran perfect for more than 25 years. Only now I have the DC voltages shift on the right channel. BTW. I posted this in a separate topic and will provide updates regarding repair attempts.




12-Nov-2019 12:11 AM



Posts: 131

Following those resistors, both Zener's D12 and D1 dictate what should happen in each of those nodes. Look at the current requirement of IC1, then CR2 with T2.

An assembly line issue, that's the only thing I can think of.