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Marantz 2265B Strange Issue

ivandezande

ivandezande

AK Subscriber
Subscriber
I'm working on a recap and replacing a few transistors on this 2265B. I finish up and plug into the DBT, and we have issues where R801 starts smoking, but only when J022 is plugged in.
J022 supplies a strange power connection. J807, 30V comes off the power supply and goes through a 100 ohm resistor to the positive main rail. I don't understand this.

Why on earth would this be happening?

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restorer-john said:
Unloaded, is the emitter of Q801 sitting around 30V? i.e. is it regulating?

Check C772- it could be shorted.
Click to expand...
Yup, 30Vish.
I replaced C772 and its twin, maybe the silkscreen is wrong and they’re in backwards. Not sure why I didn’t check that already, thank you!
 
I also tried removing C722 and C772, no change. Something is still drawing too much power through the connection.
 
Another strange thing, I should see 45V on C772 and C722 because they’re connected directly to the rail. I see the rail voltage coming into the board…..
 
I must have something in backwards, but the 2265B service manual is not accurate to what I have. Between J703 and J707 should be 100 ohms, and I’ve got nothing.
 
ivandezande said:
I must have something in backwards, but the 2265B service manual is not accurate to what I have. Between J703 and J707 should be 100 ohms, and I’ve got nothing.
Click to expand...
I followed the traces from J703 as far as it goes and it doesn't go to J709 or J707.

Screenshot (1498a).jpg
 
There's no connection from R719 to the right to R724.
Edit to the pic since I found C722.

The other channel is messed up the same way with that non-connecting point.

Screenshot (1496b).jpg
 
Last edited:
kwayde said:
C722 should be connected to the R719 trace and ground. There's no connection from R719 to the right to R724.

The other channel is messed up the same way with C772.

View attachment 3864808
Click to expand...
Good visuals, thank you! Yup, my board matches the SM layout and the schematic is wrong.
It obviously is caused by something I changed, which would be Q701, 702, 703, 704 and all the electrolytic caps.
I know the input pairs are installed correctly, as well as the diodes.

I might as well start pulling more parts until the DBT doesn’t light up.
 
So turns out I’m just dumb. The other signal connector had gotten turned 180 and was shorting the 30V directly to ground. Awesome.

Good to go now!
 
Well, now I have another issue, no sound on the left channel. I narrowed it down to QE01 and QE07 that have very wrong voltages. Both were replaced to no effect.

QE01 (KSA992x2)
B: 0.067V
C: -18.26V
E: 0.591V
C: -19.25V
B: 0.03V

QE07 (KSC1845)
E: -18.90V
C: 0V
B: -18.26

I’m not sure why the transistors aren’t turning on when the supply voltage is just fine.
 
Nothing jumps out, but kind of hard to see close. I take it that the board worked before you started? If so I would lean toward the usual backward part, or solder mistake.

I think there is a thread that details Marantz errors and typos, did you check that for the 2265B. I do recall there being some polarity mistakes on Marantz boards. And I think on the silver dial B series.
 
Warren-Oates said:
Nothing jumps out, but kind of hard to see close. I take it that the board worked before you started? If so I would lean toward the usual backward part, or solder mistake.

I think there is a thread that details Marantz errors and typos, did you check that for the 2265B. I do recall there being some polarity mistakes on Marantz boards. And I think on the silver dial B series.
Click to expand...
Yes, working before. I will double check on that and polarity would make sense, but it’s all the same as the other channel which is working.
 
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