Debugging a stock Boss Flanger BF-2

[cosmitron]

Hi!
I just found an 15 years old BF-2 that does not work properly since ten years!! :oops:  I just forgot it until I found the dusty peddles at parents home! :roll:
I intend to 'debug' it but er... well.. I'm a total newbie and I don't know where to start.
Anyway, for those who might help, here are the symptoms.

The led is on when I plug the 9 volt battery.
Everything LOOKS OK but... there is NO effect.
and sometimes I have a strange high sound and then the flanger is working for a second fraction.

Is there any stompbox doctor here who could help?  :wink:

[vanhansen]

Start with an audio probe and go through the circuit.  It will save lots of time and you should find the problem fairly quickly.

There is an audio probe you can build easily on the GEOFEX site (link on top of this page).

Also get a hold of the schematic.  If you need it, PM me.

[Mark Hammer]

If the flanging sound visits for a moment then goes away, that indicates a few things.  First, the BBD chip works and so does the clock.  Second, the flip flop works.

This suggests to me that *maybe* the bias trimpot is loose, *or* that maybe the switching FET is somehow only momentarily connected.  That could be a hairline crack in the trace leading to or from the FET.

[cosmitron]

thanx for your help guys...

I think I'm too newbie to debug it... :?
My last solution: BUY A SUPER CHORUS!!!

[pioneer_56]

A simple way to tell if it does work without replacing anything is to plug it in and try slowly turning the trim pot inside and see if you get any sound. That could be the only problem.

Andrew

[nelson]

lol if your not willing to fix it I will take it off your hands...........

[Eb7+9]

I'd replace the electrolytic caps in the supply lines before doing any trimmer adjustments ...