The guitar player tosses me his MXR Noise Clamp, a pedal which he very much liked, but also which very much would not turn on anymore.
“You want to try to fix this thing?”
What a ridiculous question.
The pedal showed no signs of life at all – no LEDs would light, no sound passed, whether using a battery or plugging in a power supply. The PCB is all surface-mount components, but there isn’t much there and the components are somewhat large for surface-mount. Nothing looks amiss upon inspection, and I was unable to find a schematic on the interwebs. However I was able to find an article referring to an allegedly recurring problem with the power input diodes on MXR pedals.
Taking the hint, I checked out the D3 diode and sure enough, it was not passing current. Replacing it with a (ridiculously over-sized) through-hole diode from the parts bin got the pedal running good as new in a few minutes.
Someone owes me a beer or two.