Here’s an Ibanez TS9DX Turbo Tube Screamer we’ve just repaired.
The pedal came in with a common fault: the switching was intermittent.
This is usually due to the foot switch wearing out, however the foot switch in this pedal was fine.
After some prodding with a high tech implement (a chopstick!) I found that moving one of the transistors in the switching circuit turned the overdrive off.
Further inspection of the PCB, showed that the solder joint on one of the legs of said transistor was broken. I’ve had to explode the photo quite a bit, but the duff joint is in the middle.
As is often the case with pedal and amp repairs, it’s finding the fault rather than effecting the repair that takes majority of the time.