Help needed with MXR Phase 90 repair

[dangeroso]

Here's the problem. When bypassed, the signal is fine. When the effect is activated, however, the LED lights up but the signal is very low in volume. With the amp cranked, you can just barely hear the phased signal. The problem is there on battery power, or line voltage.

FWIW, there was no shock to the unit, or other trauma. One day it worked, then suddenly it didn't.

Any ideas as to what element is not working would be very much appreciated. Thanks in advance.

[Mark Hammer]

Check the continuity of the switch. There is grease inside the stompswitch, and sometimes when there is too much heat applied during soldering, the grease flows along the contacts inside and forms a high-resistance barrier to signal.

[dangeroso]

Are you talking about grease getting on the board, or are you talking about a problem inside the switch? I've inspected the board fairly closely, and haven't seen any grease.

[Mark Hammer]

Inside the switch. As near as I can tell, that grease accounts for a huge proportion of what people report as "switch failures". The good news is, it is often reparable.