Boss TU-2 won't turn on

[andie92]

Hello guys,
I've got a Boss TU-2 that won't turn on. More precisely, it powers up fine (both with power supply and battery). I can also change the stream/cent and mode settings with no problem. But when I try to turn it on, nothing happens.
The switch works well, I've tried it with another boss pedal. If plugged in, the signal passes through (as expected from a turned off pedal) so I guess it's not a power issue. It just won't turn on...

Here's the wiring diagram: http://www.synfo.nl/servicemanuals/B...VICE_NOTES.pdf
Can anyone give me a clue?

Thank you very much

[darkfenriz]

Looks like the micro and power are alive, so switching circuits (jfets?) or analog path (zero crossing w/hysteresis?) are suspect.
If you're lucky the pcb-to-pcb (or is it ribbon) connections are just loose so worth cheking out.
Do you have the scope and electronics faultfinding experience?

[andie92]

The ribbon connections are good.

Do you have the scope and electronics faultfinding experience?

Actually no, but I have some basic knowledge in electronics. So if you could give me more details on how to proceed, I'll try and do my best.
I only have a multimeter but I could get my hand on an oscilloscope.

[darkfenriz]

First I'd check the voltage of the FXC signal on the pin14 of connector of either main pcb or cpu pcb. Does the level change when the pedal is turned on and off?

Also analog signal levels when playing notes at IC2 pins 7 & 1 (main pcb) can give some answers.