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Re: been there before(twice)

Tea,

It is common for the sides of the transformer can to be sucked in. Remember the can is full of melted roofing tar just like McIntosh uses in their manufacturing process today.

If you want to duplicate the sound of your MC240 when it was new you will need to invent a time machine. These parts have a shelf life. Sid Smith who was the cheif engineer at Marantz said he always changes all of the old caps to new ploy types as they sound so much beter in the 5, 8 and 9 amps he works on. I have to agree with him. If you want to keep the amp original just look at it and do not plug it in. If you want to listen to it change all of the caps to new types and only change resistors if you see a wrong voltage when the unit is powered with no single. You will need an original schematic and a quality voltmeter like a Fluke or equivelent. The main cost in working on an old amp like the 240 is time. If you can solder and read a voltmeter the rest is common sense. Antique Radio Supply has ' orange drop' caps which give a nice vintage sound. Check all of the critical 'match within 5%' resistors on the schematic. On another post you commented on the sound of RCA 5751s but you will never know until the amp is operating properly.
I have worked on maybe 10 or 15 of these over the years and I have come to the conclusion it is just beter to replace all of the caps and be done with it rather than waitin for the next one to fail. If you rebuild the amp it should not need service for another 35 years.


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