MXR Analog Delay circuit board

[rspst14]

Hey guys, does anyone have any pictures of an MXR analog delay board?  I'm trying to repair one of these, and it would be a big help if someone could post a decent pic of the board.  I've already ruled out the power cord and the switch as the source of the problem, I want to make sure all the components that are supposed to be on the board are there.  Any help would be appreciated.  Thanks.

Ryan

[cd]

What *IS* the problem?

[rspst14]

I don't know what exactly is wrong, but I want to make sure nothing is missing from the board before I try to fix it.

Ryan

[ExpAnonColin]

Is it the green monster delay?  The R5101 chips in those fry all the time... trace up to the chip and see if you're getting anything right before and right after it.  

-Colin

[mrsage]

How do you do that?

The tracing, I mean...

I've heard people mention doing that before...and using an audio probe...

Is that the same thing? How does that work? What does it accomplish?

Sounds like it would be a useful tool for my troubleshooting toolbox (in addition to the multimeter...thanks for that, by the way...it's been quite useful).

[ExpAnonColin]

Yeah, tracing, audio probing... you're basically following the guitar's signal deep into the circuit.  If you find out that the guitar's signal is just fine right in front of a chip, then is gone at the output, it's probable that there's something wrong with the chip.  This is basically testing for bad parts of the circuit.

-Colin

[rspst14]

Yes, it's the green analog delay.  I bought it dirt cheap a while back thinking I might be able to fix it.  The plug on the power cord had been cut off, so I replaced that.  It's been my experience that the stomp switches go bad quite often with these old MXR pedals, but this one checks out okay.  Is there a place on the site that explains how to trace with an audio probe?  Thanks.

Ryan

[ExpAnonColin]

Unfortunately, there's a pretty good chance the hard to find R5101 is broken...  Check out Aron's debugging tutorial http://www.diystompboxes.com/pedals/debug.html or geofex's http://www.geofex.com/fxdebug/fxdebug.htm

-Colin