We had a couple of interesting McIntosh C2700 repairs in the shop recently. In the first case the remote control was not working. Bob the Tech isolated this to a poor solder joint on the IR sensor. The IR sensor normally picks up the signals from the remote. In the first photo you can see how the highlighted pin is floating in the plated through hole. From the back side of the board, shown in the second photo, it’s apparent that the solder adhered to the pin, but didn’t flow into the plated through hole. The contact with the board was intermittent and the result was the remote control wouldn’t work. The third photo shows the reflowed joint. With that joint reflowed and the front panel reinstalled, the unit worked great.
A second C2700 arrived with an intermittent problem, where one channel would occasionally drop out. Just putting the scope probe on the board would get it working, but flexing the board would cause it to fail again. Bob the Tech isolated this issue to a small solder ball lodged between the first two pins on the tone control device. The larger photo below shows what we found. The left channel signal is on pin 1 of that device, and pin 2 is a ground. When the board is flexed, the solder ball made contact between the two pins. The signal shorts to ground, and the channel drops out. Simply removing the solder ball had this unit running reliably.
If you have a McIntosh C2700 in need of repairs, or any McIntosh preamp vintage or modern, contact Bob the Tech Audio for your service needs.
