Mcintosh C28 Stopped Working
- Thread starter Pmonk
- Start date
damacman
Resident Psycho
C28s are notorious for this as they have more knobs, dials, and switches on it than any other preamp that I know of. In addition, none of them are sealed. I JUST went through mine. The tape selector switches were the culprit and cleaning them is a real PITA.
The problem should switch sides if you do as 62caddy suggests. If you have no audio in the Stereo Reverse position, that switch may need cleaning as well.
The problem should switch sides if you do as 62caddy suggests. If you have no audio in the Stereo Reverse position, that switch may need cleaning as well.
mhardy6647
Lunatic Member
Yeah - I'd vote for dirty controls - took some serious dedication to get mine reliably clean -- for me it was the function selector, first and foremost.
Glass half full: Now's a great opportunity to try another preamp, though...
C-28 innards by mhardy6647, on Flickr
Glass half full: Now's a great opportunity to try another preamp, though...
C-28 innards by mhardy6647, on Flickr
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Pmonk
Member
R Channel not totally dead (some audio goes through) but near dead on all R channel inputs and when you hit S reverse the problem does not follow.
And she was working just fine last night.
And to make matter worse my lap top died this morning as well.
Not a good electronic day for me.
And she was working just fine last night.
And to make matter worse my lap top died this morning as well.
Not a good electronic day for me.
Weak to zero signal at right out on all mode setting helps narrow it down.
My first instincts would be to check your RCA connections between the C 28 and the power amp.
I would then swap L & R preamp outputs to eliminate the power amplifier as the culprit.
If it's still there, proceed to cleaning switches as the others have suggested.
Sorry to hear of the other problems.
My first instincts would be to check your RCA connections between the C 28 and the power amp.
I would then swap L & R preamp outputs to eliminate the power amplifier as the culprit.
If it's still there, proceed to cleaning switches as the others have suggested.
Sorry to hear of the other problems.
Pmonk
Member
Doing a full check this morning thru headphones, the only mode that has no sound is L + R to R.
If you turn the C28 on and off you certainly can hear the noise of the machine in both channels
Listening thru headphones (which is tough since the jack is all screwed up), all the other mode selectors work and I have a strong feeling it is one of the tape selectors as well.
If you turn the C28 on and off you certainly can hear the noise of the machine in both channels
Listening thru headphones (which is tough since the jack is all screwed up), all the other mode selectors work and I have a strong feeling it is one of the tape selectors as well.
I may sound like a broken record but just had it crop up again in a MA6100 in for a complete restoration.....bad ground drain.
Usually can get a hint of sound by manipulating controls if the are dirty.
After forty years of faithful service any C28 deserves a complete restore.
Usually can get a hint of sound by manipulating controls if the are dirty.
After forty years of faithful service any C28 deserves a complete restore.
dshoaf
That high voltage buzz
Pmonk
Member
Weird. I turned on the C28 to give a listen with the headphones and experience the same problem with the right channel.
I pulled off the top shield cover where the output levels are (headphone, bass trim, etc...) and heard the usual static as wires are moved and started moving the input levels back and forth when all of a sudden I got the right channel back.
Hooked it back up to my main system and everything works well, so I'm pretty sure its just a maintenance issue (lets see how it responds to an overnight power off)
Will get the C28 serviced when I get my MC2505 back.
Moral of stories - old electronics can drive people nuts?
I pulled off the top shield cover where the output levels are (headphone, bass trim, etc...) and heard the usual static as wires are moved and started moving the input levels back and forth when all of a sudden I got the right channel back.
Hooked it back up to my main system and everything works well, so I'm pretty sure its just a maintenance issue (lets see how it responds to an overnight power off)
Will get the C28 serviced when I get my MC2505 back.
Moral of stories - old electronics can drive people nuts?
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I don't see any clinic stickers.....if you would have brought this unit into a local amp clinic say 20 years ago, DOB would have had your local guy like me do the needed 4-5 hours service on their nickel.....
boosted mahi
New Member
Many a man has lost his marbles working on old BOATS! :thmbsp:
