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C2200 Balance Control has become Input Selector!

atkinsonrr

atkinsonrr

New Member
Hello all --

I turned on my system this morning and noticed R channel output is lower than L channel output on the meters of both preamp and amp. When I push the mono switch both channels sound and look to be on the meters at the same level. Now here is the strange part. When I tried to check or adjust the balance control, it would display the balance (20 to 30 or more higher for the left channel) but then immediately turn itself into the input selector. In other words, turning the balance knob now selects the input! This is similar I think that happens during setup. Probably unrelated, but when tone controls are not bypassed (I always use with them bypassed) and when the treble control is operated in the extreme counterclockwise area is shows spikes in the right meter and static through the speakers, regardless of how many times I clean the pot.

I did a search here on C2200 problems and found two only somewhat similar. One was titled "C2200 - strange behavior..." from a guy in Poland who traced his balance problem to bad solder joints and a relay. But he did not report this balance/input control interaction. A second earlier post is titled "C2200 Hyperactive Input Select Switch". In that one the input switch was skipping over inputs. Dshoaf suggested it was probably an optical encoder "that's actually just connected to the main CPU/controller device". The poster sourced the part and was not heard from again, so I assume it fixed the problem.

Is it possible to jumper around the balance control to solve this problem? I never use the balance control so this would be a pain-free solution. It appears it may be more complex than simply removing a control from circuit would correct. If that's the case, is there a way to bypass the setup circuit that I am thinking is involved here?

I would be fine with a short term solution even if it bypassed balance control, input control and setup. As mentioned above I never use balance, only use one input and never use setup. I am in France and any McIntosh tech is far away in Paris. And I would probably not see my preamp for many many moons. I am fairly competent with a soldering iron and am hoping someone here could coach me thru this.

Thanks -- Rob
 
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You need to talk to Patrice at Clinique Audio SAS, 27480 Bosquentin. He is one of our members here and had tremendous experience and expertise working on Mcintosh equipment. His name on this site is "clinic-audio."
 
If the 2200 controls are menu/microprocessor controlled, a factory reset might clear any logic programing confusion that the preamp might have experienced from a common at this time of year, power blip.

If the owners manual is available, it most likely provides the method, like my Mc. C 220 preamp does..

Just a thought.
Good luck atkinsonrr(Rob)
 
Hello Jlovda and Bill. Regarding Patrice. He and I exchanged several emails and then we talked on the phone 2 or 3 times about many things, not only audio. Shared stories about the U.S. and love life, etc... We got along great! And he had mentioned possibly buying my MC275. Then he simply disappeared. Is he still alive? I never got answers to emails and never knew what happened. I can try again, though. Yes Bill I think the controls go thru a microprocessor and they change function based on if you are in setup mode or not. And the method in the C2200 for reset is to hold the 'mute' button and the 'outputs 2' button at the same time for 5 seconds. Unfortunately when I do this nothing happens.

I do have progress to report however! I pulled the front panel so I could get a better look at the microprocessor and to see if I could clean contacts, etc. And also cleaned and reseated all of the connections that run from the face to the main board. I then put everything back together and fired it up and now the balance control works like a balance control and does not revert to being an input selector. However, the unit still acts like the left channel is down in volume. What I mean is that, when the balance control indicates 0 correction, the L channel is down by the same amount it was. BUT now I can use the balance control to correct it. When the display is showing +5 to the L the meters and the sound seem balanced.

I am wondering if I disconnected the central ribbon cable and reconnected if I would be able to "re-zero" the balance display. But afraid it will take me back to square one.
 
Hello atkinsonrr

Then he simply disappeared. ?? No very strange , I am here and my mail box still work
Is he still alive? of course I am
I never got answers to emails and never knew what happened. Sometimes I don't answer immediately but I always answer within 48 hours (too much messages)
I can try again, though , yes please try again

regarding troubles with your preamplifier I never saw that before but I will suspect the microprocessor
And the method in the C2200 for reset is to hold the 'mute' button and the 'outputs 2' button at the same time for 5 seconds. Unfortunately when I do this nothing happens , this make me think that your processor is bad or sick
 
Hello twiii. Yeah, for sure. When we live with tubes, swapping tubes is almost a reflex. And when I did, the problem stayed with the R channel. But in this case even going into it, I knew the strange behaviour with the controls could not be due to a bad tube.
 
Hello all - Just following up on the resolution of my issue. First off, thanks twiiii. I have a service manual for the unit also. Upon more checking, it turned out it was a bad interconnect from DAC to preamp. I had previously swapped interconnects but I remember now that I had switched the interconnects at the DAC end, so the affected channel did not change (dumb mistake). And I have no idea why the balance control/input issue and the R channel down in output happened at the same time. The only remaining issue is the unit still will not perform a reset. But this is not affecting anything at present.
 
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