C22 Issue

cjmustang69

Well-Known Member
I have owned my C22 preamp (original version) for just over 3 years. It had received a Deluxe Rebuild by NOS Valves in early 2015. It has always performed very well, without any issues at all. As I have several systems, it sees intermittent play. Last evening, I decided to hook it up to my MC2255 amp and Valencia speakers. When I toggled the power switch - nothing happened. No display lights, no sound, nothing at all. I switched power outlets to ensure the outlet wasn't issue. It wasn't. I also checked the 1 amp fuse. It looked good. Just to be certain, I switched in a new fuse. It had no effect.
I had last played the C22 about 2 weeks ago and there was no hint of issue when I listened to it - or when I powered it off. Just posting this in case anyone has Idea of what issue may be. I suspect I'll need to contact Ryan at AudioClassics and see if they can look at it.
 
It appears that there may be a surge suppressor in the primary winding circuit portion, I would suspect that if the power cord and plug look good, power switch second, power transformer last.
 
It appears that there may be a surge suppressor in the primary winding circuit portion, I would suspect that if the power cord and plug look good, power switch second, power transformer last.
Thank you for posting the above thoughts. The cord and plug look perfect. Once I get past checking the cord, fuse and outlet - I'm beyond my technical ability. I believe I'll be driving home early next month - hopefully AudioClassics can look at it while I'm home.
 
Plug the C22 into a working wall outlet.

With the power off, plug a lamp into the RED ac outlet on the back of the unit. Turn the lamp on. Does it light?

Next, turn the lamp off and plug it into the next BLACK outlet on the back. Turn the lamp on, then turn on the C22. Does the lamp light?
 
Plug the C22 into a working wall outlet.

With the power off, plug a lamp into the RED ac outlet on the back of the unit. Turn the lamp on. Does it light?

Next, turn the lamp off and plug it into the next BLACK outlet on the back. Turn the lamp on, then turn on the C22. Does the lamp light?
I’m away from home now, but will try as you suggested later this afternoon and post results
 
Not certain exactly why, but my C22 is working now!! I moved it to another outlet to try procedure suggested above by "jkaley". Prior to connecting a lamp to any of outlets on back of preamp, I toggled the C22 power switch - and it powered up properly. I just moved it back into system and it is playing normally. I'm not certain what issue was - however, I do know I plugged my Squeezebox Duet receiver into one of the outlets on back of C22 preamp prior to attempting to start System last evening. Given the suggestion to troubleshoot issue by "jkaley" above, I suspect this contributed to situation. Just not certain exactly how?? As always, I appreciate the helpful comments/suggestions from AK members!!



IMG_1365.JPG
 
The power switches on the older Mac preamps are underrated for switching amps and have no arc supressors. Cycling them several times doesn't hurt, but do it unplugged.
 
The power switches on the older Mac preamps are underrated for switching amps and have no arc supressors. Cycling them several times doesn't hurt, but do it unplugged.
I had cycled the C22 power switch several times last evening - but to your point above - it was still plugged into outlet. This afternoon was first time I cycled it unplugged. For my understanding, when you refer to "switching amp" above - are you referring to the MC2255 amp?
 
Glad it's working. Might be a cold or loose solder joint on the power rail for the aux outlets I'm guessing.
 
no , aux outlets are not involved to power the unit on , I would suspect the power corditself or bad contact at the plug
 
I had a similar situation on a MX114 before it was restored. The power cord at the plug sometimes worked and other times did not. New cord was the fix.
 
no , aux outlets are not involved to power the unit on , I would suspect the power corditself or bad contact at the plug
I'm far from an expert, and I don't have a C22, but the black aux power outlets appear to be wired post-switch but before the fuse and transformer primaries. Wouldn't a break here affect power getting to the fuse or transformer? I defer to the experts.
 
I'm far from an expert, and I don't have a C22, but the black aux power outlets appear to be wired post-switch but before the fuse and transformer primaries. Wouldn't a break here affect power getting to the fuse or transformer? I defer to the experts.
I somehow believe the power outlet on back of C22 created the issue. I've never used the power outlet on back of C22 - until last evening. I've never had any issues with the preamp until last evening. I always follow same routine of starting my systems up - preamp powered up first, power amps powered up last. I had plugged the Squeezebox into back of C22 (black outlet) - prior to attempting to power up C22 and prior to powering up MC2255. The C22 wouldn't power up at this point. I intend to use this system for the next several weeks, so will have opportunity to see if issue returns (there will be nothing plugged into outlets on back of C22)
 
A long shot guess (possibility)
Is it possible that outlet is controlled by a light switch that may inadvertently been switched off. Sometimes it only effects half the outlet?
It happens and it would mean there's nothing wrong with your c22
 
A long shot guess (possibility)
Is it possible that outlet is controlled by a light switch that may inadvertently been switched off. Sometimes it only effects half the outlet?
It happens and it would mean there's nothing wrong with your c22
No - I had it plugged into my Monster AVS2000 power center.
 
I'm far from an expert, and I don't have a C22, but the black aux power outlets appear to be wired post-switch but before the fuse and transformer primaries. Wouldn't a break here affect power getting to the fuse or transformer? I defer to the experts.

Hello

you defer to experts ....I am .
I work on MC INTOSH units over 42 years long
If you have any doubt see my attached picture :

C22-power-supply-schematic.JPG
you will understand what I mean when I say " AUX sockets are not involved "
 
If replaced with a polarized plug cord, the narrow blade side goes to the switch. Change the primary wiring to put the fuse in series with and before the switch if necessary.
 
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