A Pair of McIntosh MC7205 5-channel amplifiers recently found their way to Bob the Tech Audio for repairs. These units had similar issues. They had front panel lamps out, sticking meters, and one of the two had a pair of channels out. We diagnosed and repaired the channel, reworked lighting, and rebuilt the sticking meters. We tested to verify both units perform to factory spec, and sent them on their way back to happy customers. Read one of their positive feedback here.
One of the two units had had an LED replacement done, but it had shorted and failed. We reworked both units with new, original, incandescent lighting. This is a major subject of debate, but we like incandescents because it’s consistent with their vintage nature. A couple of photos below of the original LEDs and burnt incandescent bulbs, and the replacement lamps going in.
These amplifiers have the heatsink outputs passing back through relays on the driver boards and out to the speaker terminals. The driver boards handle two channels. A failed relay on one driver board caused intermittent outputs on those two channels. A replacement relay quickly had the channels running great.
The meters on these two units were a bit of a challenge. We needed to disassemble the meters and tweak to eliminate interference between the meter movement and meter body. In one case the meter cards had warped from the heat of the meter lamps. We disassembled these meters, refastened the cards to the meter back, and then reassembled. These are fragile devices, but Bob the Tech did a great job.
Just before final reassembly, we replaced the disintegrated original light-isolating foam. We also repositioned the blue gels for the meters and reattached to the glass. The original condition of the inside of the front panel of one unit is shown in the photo. Unfortunately, we could not address the yellowing of the meter card. Replacements are no longer available, hence the inconsistency in the coloring from one to the next.
If you find your McIntosh MC7205 (or a pair of them) is in need of repairs, contact Bob the Tech Audio at our service request link, here.
