I recently scored a Mac 2105 of Craigslist here in Pittsburgh. The price was right at $400. I gave it to my friend and fellow Polkie falcon377 (Mike) to check out.
Mike powered up the unit, played it and said that it sounded pretty good. The plan at that point was to clean the chassis, controls, contacts, replace bulbs, repair some bubbles on the faceplate, etc.
Mike opened the unit and to our surprise, non of the caps matched the parts listed in the service manual. After several emails to Mac and additional research Mike concluded that someone has been isnide the amp and must have rebuild it using a 2505 schematic, at least that's our theory because of the values of some of the caps he found on the boards. Why the tech wouldn't replace a like for like component is beyond all logical comprehension. For example, the big power output caps were 50V, 25,000 uF made by GE (see pic)
Any email to McIntosh confirmed that they never used this part or value in the 2105.
I won't detail the differences in the boards cap by cap, but here is a view of the chassis as found:
I ordered some replacement parts according to the 2105 Service manual. Most of the caps I ordered were various radial and axial varieties of Nichicon. The large output caps that we ordered were Mallory 50V, 58,000 uF. Mike meticulously cleaned the chassis, controls, soaked the pots in DeOxit, replaced all the lights and polished the chassis to a very good condition. The apparent "bubbles on the front galss panel were actually deposits on the outside of the glass. These were removed and the unit looks and sounds fabulous. It is paired very nicely with my MX-113. Here are some pics of the rebuild chassis:
The resulting change in performance and sound was striking!!:yes: The unit was much more dynamic and had a better or lower bass response. Overall, I put about $300 into the unit, the total project cost about $700. This compares very favorably to the cost of what some of these untis are selling for.
Kudos to Falcon377 (Mike) and his expert restoration work. I can't thank you enough.