carbon copy troubleshooting

[hisheroisthrash]

hey everybody,

i'm new here and still pretty new when it comes to messing around with electronics.
i recently obtained a free MXR M-169 Carbon Copy delay pedal.  
the catch is that it's not working properly.
i know it's not really a "diy" project, but i was wondering if anybody might be able to provide some insight and/or guidance.

when in bypass, signal passes through and everything's okay.
when the effect is engaged, signal stops passing through and the indicator LED does not light up.  
when the "mod" switch is engaged, however, the "mod" indicator LED does light up.  so i know power should be making it to the board.

here's how far i got with a multimeter (mainly just checking continuity).  
this is how i'll refer to the footswitch terminals, when looking at the underside (looking down at the terminals, not the "stomp on me" side:
input side  ---> 1  2  3  ---> output side
                       4  5  6

when the effect is "off", both tips and sleeves of the input and output jacks are reading ok (signal is passing / continuous).
the tip of the input jack reads continuous with switch terminals 2 & 3.

when the effect is "on", the sleeves of the input and output jacks read ok, but the tips do not.
the tips of the input jack reads continuous with switch terminals 2 & 3.
the sleeve of the output jack reads continuous with switch terminals 2 & 3.

i know that, with the sheer amount of stuff inside the pedal, there could be a million things going wrong.
using my (*very*) limited knowledge of electronics, i'm guessing that it may just be something going on with the footswitch, since part of the board seems to be getting power, but the effect on/off indicator LED doesn't activate and signal doesn't seem to pass from tip to tip when the effect is engaged.
would any of you have any suggestions regarding what may be going on and recommendations for fixing it or, failing that, any recommendations for further readings / troubleshooting i should do to try and narrow down what's going on?

[Govmnt_Lacky]

Unfortunately... the carbon copy is a relatively new design (I believe  ) so you may want to post some decent pictures of the inside of the pedal for more assistance. Since schematics are probably not easily found... pictures will be the only way to spot a problem.

[gulnare]

Hey all, apologies for thread resurrection,

I'm trying to repair a Carbon Copy, just replaced the J117s (net searches show this was a common problem) and now have delays again.
If I make it self oscillate then turn the delay time down to minimum it ramps up the sound (as intended) but oscillation and delays cuts out when the time gets really short. Turning the delay time back up and the delays gradually return, fairly distorted at first then clean up.
I've tried tweaking the trim pots to clean it up, but not having much luck.

Is this something to do with the BBD chips? Or do I have a dead/dying electro somewhere?

I can post readings if anyone has pointers on where to measure.

Cheers,
Matt.

[alexradium]

oscillation is normal with this one on max feedback and depending on time also.

[gulnare]

Yeah, I want it to self-oscillate, and it does, but not when the delay time is turned down really short. It's like the BBD chips crap out when it really gets going and the oscillation and repeats stop, then slowly return to normal operation when the delay time is turned up and feedback turned down. My BYOC analogue delay doesn't stop oscillation under these conditions, and I was hoping to get similar sounds out of the CC.