Need Help With DOD FX60 (Bypass LED Problem)

[Paul Marossy]

OK, so I have a DOD FX60 on my bench for evaluation/repair. So far, it sounds like nothing is wrong with it. However, I did notice that the LED never really comes on or goes off when switching. It's just glowing all the time, very dimly.

So... my question is, what do I look for as a cause for this problem? I already tried replacing the transistor connected to the LED, but no change. It uses a 4007 IC chip for the bypass switching. I am wondering if possibly the 4007 IC chip is faulty. Is there some way to test it to see if it is? Also, I am wondering if this could cause an occassional crackling sound  - this is what is reportedly wrong with the unit.

Here is the schematic: http://files.effectsdatabase.com/docs/schematics/dod_fx60.gif

Any help would be much appreciated!

[Paul Marossy]

OK, so does anyone know where I can get an MC14700-UBCP IC chip? Do they still make these chips?

[Paul Marossy]

I got a CD4007 IC chip from Small Bear, but my problem with the LED persists. I suspect that someone replaced the original LED and it's not acting the same way in the circuit as the one originally used. I've tried other LEDs, and none of them work, either. Some of them won't even light up at all. 

So, apparently the transistor is not switching off the LED. What do I need to do to make it switch the LED off? I'm guessing that I need to play around with the value of 10K collector resistor a bit?