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Quad II / 22 only getting output from “Yellow” channel

jefferylhenr

jefferylhenr

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I got this Quad set in a box. Went through everything and have both amp modules working and stable. Only getting sound out on the yellow channel. I can swap the yellow and blue and get good clean sound out of either Amp / channel so I know the amps are good. I know the mono / stereo buttons shut down one of the amps. The on/off switch and the amps are powered via their individual cords. As far as I have measured, I have equal power coming in to the 22 control unit on both yellow and blue legs. Swapping the signal inputs make no difference and all 4 tubes are energizing. Swapping the tubes makes no difference as well.

I have never been in one of these so any ideas would be helpful. The blue leg is pulling 780ma and the yellow 840. When I swap the yellow and blue, the main line draws follow.
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jefferylhenr said:
I got this Quad set in a box. Went through everything and have both amp modules working and stable. Only getting sound out on the yellow channel. I can swap the yellow and blue and get good clean sound out of either Amp / channel so I know the amps are good. I know the mono / stereo buttons shut down one of the amps. The on/off switch and the amps are powered via their individual cords. As far as I have measured, I have equal power coming in to the 22 control unit on both yellow and blue legs. Swapping the signal inputs make no difference and all 4 tubes are energizing. Swapping the tubes makes no difference as well.

I have never been in one of these so any ideas would be helpful. The blue leg is pulling 780ma and the yellow 840. When I swap the yellow and blue, the main line draws follow.
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Cancel that tube order. While you're at it, cancel this thread. You already have two threads on the same subject which is a AudioKarma no no.

You can address everything about your preamp and amps in the single thread.
 
Two concurrent threads merged. One thread per subject please.
 
I may be getting old but two threads? Not sure where that came from? And I only see one thread in my content. Hopefully now that everyone has their nickers back on…

Yes, yellow works on either module and have proper pin voltages on the tubes. I opened up each connector and resoldered and they are good. Voltages per this schematic.
1718831214046.png
 
You only see one thread because I merged the two threads together. Post #1 and 5 are from the first thread you started and the rest are from the second thread.
 
jumper from the tone control side of C16 to the tone control side of C17 and see if you get sound from both channels.
 
I'll assume I meant there, not familiar with the physical construction here, I can only read the schematic. If thats the bass pot though, thats the spot.

ok so the problem is upstream of that point. We can now rule out problems from the bass pot all the way through the output cables.

what does a jumper from pin 7 of V4 to pin 7 of V3 do for you?
 
I think I have it traced back to the blue volume pot. The on off is non functional and someone probably over cranked on it. Anyone ever pull one of these apart and successfully get it back together?
 
The volume / balance / on / off is a bugger on these. Finally got it reading correctly on both the “yellow” and “blue” channels. Put in the new set of tubes in the 22 and boom, we have good clean outputs on both channels. 1719524602594.jpeg
 
And from the beginning of this thread the most ridiculous issue to solve was duplicate posts… if you arrow back on an iPad and push the post reply button, it will post again. Heaven forbid if that ever happens to anyone else…
 
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