McIntosh "2505-2"

[visim91]

I recently realized that I have the "Mcintosh 2505-2"

I also recently stumbled upon this "upgrade" for the McIntosh 2505-2:
http://sportsbil.com/mcintosh/Amps/MC2505/MC2505_ser_b.pdf

Where do I find the serial number referred to in this document on my amp to confirm whether this upgrade is applicable to me or not?

Thanks.

 

[c_dk]

Only affects first 149 units....noted in the first of 5 MC2505 schematics as a service note.

 

[CountD]

You don't need an upgrade. In all the Mc2505s I have owned, only one was the regular version - the plain Mc2505. The regular Mc2505 differs slightly from the -2 version in the way the meters are mounted (a bit back from the glass), and a couple driver transistors mounted on the chrome chassis near the heat sinks instead of inside like the -2. That's the way mine was.

 

[c_dk]

They had many revisions over its production run....thats why there are 5 schematics.

 

[visim91]

Thank you c_dk, for clarifying. Much appreciated.

 

[dealcrazy1]

Hello,
My father gave my husband and me his beloved Macintosh stereo units as a Christmas present years ago. I have many fond memories of the two of us listening to classic rock with them and the ADS 910 speakers. (Heavy suckers).
They are: pre amp c 26, tuner mr 77, power amp mc 2502-2
My question is, what is causing the poping and crackling when I turn up the sound ? I had it "looked at" a few years ago but it still does it. I hesitate to leave my beloved possession with anyone so I just live with it.
PS- I was suprised to learn all of these are still very collectible! WOW!
Any help would be appreciated.

 

[c_dk]

Could be a number of things.......

Volume controls, selector switches, and amp gain controls liked to be excersised often. Just sitting in storage will allow contacts to oxidize and crackeling while moving will happen when finally used again. Vintage audio equipment gets lonely and cantankerous when not used often......

There are correct cleaning solvents to use in specific locations to deoxidize and lubricate those contact surfaces.

If the noise turns out to be constant, certain transistors could be failing and need to be replaced.

Certain parts inside the units had decade long life expectancy. Being that these units are 4 + decades old they are do for upgrading when the units are restored.