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

Nikki, with all due respect to Almarg, you don't want to operate it AT ALL! The electrolytic caps are probably shot, and even if they aren't, they have to be brought up to power slowly with a Variac. Don't even worry about the tubes at this point!

The best person to put this little gem back in shape for you is Terry DeWick in Knoxville TN.
http://www.mcintoshaudio.com/dewick_repairs.htm
Terry is a McIntosh wizard and does most of the important McIntosh repair and/or restoration for owners all over the country (including me!)

As for another one, singles often come up here on Agon, on eBay, and you can ask Terry as well. He can give you tips on cleaning the chrome and other info, so don't hesitate to call him. Also, if your amp has a pair of ORIGINAL KT-88's (made in the UK) and they have good getters (still fairly silvery on the top and both sides of the tube) those alone are worth $200 to $500 a pair!

Definitely a keeper ;-)
.

It would obviously be desirable to run the tubes across a tube tester, but if you don't have access to one I think it should be safe to try the amp without first testing the tubes, PROVIDED that you use a variac or equivalent to bring up the voltage very slowly, as I described. While you do that, look for any reddening of the plates in the tubes, as well as excessive warming of the transformers, and of any electrolytic capacitors which may be on top of the chassis. Obviously, don't go underneath the chassis unless you know exactly what you are doing, or there is an electrocution risk, even for some time after power is removed.

To help the chrome on similar vintage components, I've simply used commonly available metal polishes which list chrome as one of the metals they are suitable for. Such as Noxon, which you can find at supermarkets and hardware stores. There are also chrome-specific polishes, used for automotive and motorcycle purposes, but I'm not particularly familiar with them.

Apply the polish with cloths or cotton swabs, being very careful to get any of it on the lettering, and being careful not to get it into crevices from which you may not be able to wipe off the residue. Then wipe it off as directed.

Regards,
-- Al

Nsgarch,

Of course I can't say with certainty that the tubes are the original units. I can say with certainty that they are Genelex KT-88s made in the UK (as stated on the tubes). The tops appear quite silvery. The sides look to be somewhat brown. I would also like to clean the tubes as it's clear people have touched them over the years and left some finger prints.

The caps for this model are all inside the base. Any suggestions for testing the caps?

I do appreciate the cautionary comments. I have a reasonable amount of experience working with electronics and some higher voltage stuff. However, my classes seemed to have skipped the section on tube based circuits ;)

I'm not sure I have easy access to a variac but I will check if I decide to plug it in. I also will give Terry a call.

Almarg,
The cleaning/ polish plan sounds like what I had in mind. Brasso and lots of TLC.

Oops! The first sentence of the last paragraph of my preceding post should have read:

Apply the polish with cloths or cotton swabs, being very careful NOT to get any of it on the lettering, and being careful not to get it into crevices from which you may not be able to wipe off the residue

-- Al

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

http://www.audioclassics.com/