Hello all.
I just took over a project amp mc2505 from the owner who never had the time to work on it. He did not know exactly what the problem was, but he did buy a new glass faceplate some time ago for it(never put it on yet). Also, one of the knobs is pulled out(not missing) and I can pull another knob(with shaft) out easily. So a few questions:

Any opinions on this amp?

Are the knobs - with shaft, easily pulled out with the faceplate off?

Is there an exploded diagram of the unit showing faceplate, and how the peices fit together?

Are there other McIntosh forums to get info from?

I do have the document showing some of the schematic and block diagram, but no owners or operater manual.

My goal is to fix this amp up and keep it. Also to learn about Mac products

Thanks.

Firstly, does the amp work? Is the project only to cosmetically get it up to snuff?

The knobs of the older Mc (please do not use Mac - that's a computer) had a steel spring for tension that was quit stiff. If the knowbs have not been pulled for some time, it is possible a bit of corrosion has also increased the difficulty. I've experienced this on a couple of my Mc units. Most of the time a constant pressure will get them off. I don't know of any of its controls that permits the shaft to be pulled out so I suspect, you'll need to replace whatever control it is. If they are too stubborn, you may want to address the question to McIntosh Labs service department since. Since you are replacing the faceplate the double spoon may work well but, expect that method to crack the faceplate. I coat the shafts with a little light oit before replacing the knowbs on my units.

McIntosh will have copies of the owner's and service manuals that you can still purchase. Also, the service depratment can help in putting the faceplate together, though it is rather intuitive once you have the pieces laid out.

As for the amp; I use the MC250 which is the same amp sans the faceplate and meters. I've had it for about 30 years and only retired it from my main system when I purchased its bigger brother the MC2105, same vintage but 105 watts/channel.

I powered it up for the first time yesterday and got a small "pop" then a tiny wiff of smoke coming up from where the left side main output power transistors are, so I turned it off real quick after that. So now I gotta decide what to do...... I paid $100 for it. The guy said if I don't get it working, he'll buy it back for the same price. I would hate to part it out.....
Both of the gain knobs and shafts easily come out of the unit. I can put the shafts back in place and it feels like a pot is turning when I turn the knob. I understand the front glassplate is hard to get. The guy who had it paid $100 just for the plate, so that's what he wanted for the whole unit. I have not done anything with the glass plate other than keeping it protected off the unit. The chrome on it looks very good. No rust or corrosion.
I guess I should contact the folks at audioclassics and see what they recommend. I do not want to do any more damage to it and have it cost me even more to fix. But if there are things I can check and replace myself I will.

For a cost of a hun, I would restore it! Even if it cost you $300-400, you'd still be ahead of the consignment unit audioclassics has for $700.
md

For $100, I'd keep it as a parts unit. Besides the front plate, the meters are difficult and expensive to get. I'd definitley check with Audio Classics about the controls. I remember pulling the knobs of these and having the shafts stay on but, there could have been a production change. Smoke out the bottom - usually a set of resistors cooking as a result of hopefully only the output transistors going. Hopefully, the outpts did not let go as a result of an autoformer going. Being 30 years old +, even a Mc can use a new set of electrolytics generally as well. If you have a local Mc dealer or good tech locally, I'd just get an estimate before making a decision. If you want a 2505, which is a very good amp, then keep it for the parts, if nothing else and get a working unit. They can be found in excellent condition with a little work in the $400-500 range. Ususally, the less expensive working units have bubbled faceplates that severally reduce the selling price and you'll have the fix for that on hand.

I can tell ya if you need new Pots Good Luck finding them ! No Dice at audio classics or MAC :p: themselves. Oh yeah if your changing face plates yourself be very very very carefull when changing the blue plexi over to your new one. The Plexe cracks very easy. If you decide to part your MAC :p: out let me know.

Grumpy

Actually, the pots should not be too hard to spec out but, IMHO they are not really needed and can be by-passed.

Brian

If you know where to get Gain Pots ( or any Pot ) then maybe you could share where to get them from with the rest of us.

Grumpy

Originally posted by Brian
(please do not use Mac - that's a computer)

Mmmm.. why's that, they use Mac themselves... From my waiting parts pile.

and..

MAC = McIntosh Audio Corp...

MAC=McIntosh Audio Corporation. I agree with the acronym but there is no such audio company. The is McIntosh Laboratories, located in Binghampton, NY and the makers of some of the finest audio equipment in the world.

I don't dispute that they use the model designation of MAC for the receiver line but that does not make the company MAC or Mac. It is McIntosh and not MacIntosh. I drive a Caprice but I'd not call the auto company either Corvette, Chevette or Vette. Apple and McIntosh had a bit of a scuffle about this about the time the original Mac computer came out and it was resolved that McIntosh should use Mc and Apple Mac. As for the model designation, McIntosh had first rights but waived any infringement claim against Apple. Either they figured that no one would mistake one for the other or figured the upstart computer company would just disappear and was not worth pursuing. Us older McIntosh owners are just a bit sensitive that 1) the name is abbreviated to Mc and 2) it's then mispelled. It's bad enough when I'm speaking with someone and we are discussing audio and I mention my Mc system and the response is something like "Oh, what color is your iMac?"

I remeber looking at the pots on the 250 which are the same as the 2505 some time ago and they are a standard 3 lug linear pot of, I'll be wrong about the resistance since its so long ago but, I think 250kohm. Nothing unigue or unusual. OEM probaly not available except from a parts unit but, If I were replacing I'd either bypass since I kepp them fully open per McIntosh's recommendation or go with a set of resistor attenuators.

Anybody have a glass face for the MC 2505 amp?

Got one with a crack, so need a newbie

Should be in stock at the parts department at the factory call 800-538-6576 ask for parts department.