McIntosh MC-75 in unknown condition, what do I do?

Here is another alternative. These guys are big on Mac gear.

http://www.audioclassics.com/

Nikki, for cleaning tubes I always use Ronsonal lighter fluid (naptha - the same solvent drycleaners use.) It will amazingly NOT hurt even the fragile white chalky printing on a lot of European tubes like Telefunkens! Whereas anything with water in it will take the labels right off! The labels on the KT-88's are fairly durable. They are probably Gold Lions, correct? -- that's what McIntosh used quite a lot as their OEM KT88's back in the day. Though used, they're probably still stronger than current KT88's are new -- I have a few and they all test better than the new stuff!

If the lettering on the chrome chassis is 80% intact or more, then it's worth bending over backward to save; so I'd caution against using any kind of abrasive cleaner or pad because it will remove the lettering if it's even in the same room! ;-) Terry recommends something that comes as cotton wad impregnated with some chemical that won't wipe the lettering off -- you'll have to ask him.

If you go to his site, you'll see some unbelievable restoration jobs -- amps that have been through fires, etc.

Nsgarch,

Thanks for the tips! I don't recall seeing Gold Lion on them. I'll take another look when I'm back in the lab tomorrow.

The chassis chrome is generally good. The top could easily be cleaned without ever touching the printing. The worst parts are the bends in the metal and the back where all the specs are printed. Everything is still 100% readable but hardly clean.

The hardest part of this whole thing is resisting the urge just to try the amp!

IT WORKS!

I've given the amp some TLC over the last few days. I took the lighter fluid advice and cleaned the tubes themselves. I've been carefully using brasso to clean the chrome surfaces. The rust pits are their for good but it's MUCH better. The guts looked good so slowly powered the amp up. It does in fact work. The RCA plug certainly could stand to be cleaned. It's connection to the cheap Y-cable from my mp3 player was iffy at best. The amp drove my MMG to a reasonable level.

I can't say anything about true sound quality at this point as I never feed it a good signal and really, I just have one.

I sure is a pretty thing with some cleanup. It makes me wish I could find a second dumpster 75! I haven't actually figured out what to do with this one. I would like to keep it but it's not well suited for either my MMGs nor my NHT 2.5i's. The cost of a second amp is questionable budget wise, adding new speakers on top of that is a non-starter. It's a bit like being given a Ferrari with a bad transmission. You know it's capable of so much but until you sink the cost of a nice car into the transmission you have nothing but a beautiful garage queen.

Thanks for the help all!

Nikki, it wont't cost you anything but patience and vigilance before you come up with a second one at a reasonable cost (or no cost!) It's just a matter of time and watchfulness. At that point (and it WILL happen) I bet your speculation about what to do will take on a whole new complexion! In the meantime, remember, there's someone out there in exactly the same situation as you -- just waiting for YOU to give up first !!
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