MC-240 amp restoration

S

soundman9826

New Member
hey guys i have a friend wants me to restore his MCintosh mc-240 tube amp. i just bought a Variac Variable AC Power Transformer so i can slowly power it up scene it has not bean turned on in 5 years. any help would be greatly appreciated. also i was told the best way to clean the rust off the case is #0000 steal wool is that right?

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Wow, how does such a beautiful piece of audio history get neglected so bad?

Bring it up slow, there's a whole procedure in a sticky in the tube section, I'd suggest reading through it.

Good luck!
-Tom
 
Time was stuff like this was unloved old obsolete gear nobody seemed to want, incredible as that sounds.

Sent from my SM-N900V using Tapatalk
 
Whoa ... That chassis is too far gone to be saved by steel wool. You really should come up with a game plan on the chassis before putting any time into repairing it as you may elect to strip the chassis and replace it with a reproduction chassis.

At least it's in good hands now!
 
i read the thread about using veriac to power up an old tube amp and he says to put it in the oven at 125 for like an hour or 2 but i am not sure i am to sure about doing that.do i really need to do that and if so should i leave the tubes in or take them out? also will the oven rack hold the amp as it is really heavy.
 
Since it's been stored in such a damp place I'd say go for the oven treatment. Tubes out, turn it upside down on a pan, bottom cover off. Make sure the oven isn't any hotter than 125F and you won't have any issues.

Do a thread search on 240 rebuilds. Many good, well documented projects. Also check the Mac Hints and Kinks sticky for useful info.
 
Well, yes amazing it got neglected so far down.

Ok you have to take the whole thing apart, meaning removing carefully the transformers, labeling the wire etc...

New chassis can be found.

New professional paint jobs on the bottom chassis and transformers. New decal.

Then new power supply, caps, bias check.

Then new coupling caps. Resistor check etc...

Check the tubes.

Then it will be like new :yes:

It's a big job. Done it on my personal MC225. But the result is worth the pain and $$ IMO.

:yes:
 
ok need some help. i got the amp up to full power with no problem, but dont know what to do now. i can get sound out of both channels but i have to turn it all the way up and the sound is really low and crackly and distorted. when i moved the tubes around it got a little better but not much.
 
You should read a newly posted thread in the Tube forum about the rebuild of a Fisher amp by a pro and then there are others as well. I would say if you are beginning from scratch on this sort of project you should spend at least 2-3 hours reading about how people go about bringing these back from the brink without hurting some possibly irreplaceable parts. The info is not really all in one place. My still needs the cosmetic treatment but I got it in good running order and it was a lot of work and about $300 in parts including tubes. Many many hours of studying the circuit and replacing components and testing.
 
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