Help with a dead vintage MXR Flanger

[ugly_guitar_guy]

A co-worker gave me his old 70's MXR Flanger unit to try to fix and I honestly don;t know where to start. It passes signal just fine, but when switched on it makes a very loud buzzing and has zero guitar signal. A quick look at all components shows nothing out of place or joints/traces broken so I can only imagine what could be the cause. Any help or an idea of where to begin?? Thanks!

[Scruffie]

Could be any number of things, i'd start with swapping out the CMOS Chips, they seem to go alot, bad caps could also be a culprit and Op-Amps can go too.
Hopefully it's not the worse case scenario, Dead BBD 

[Cardboard Tube Samurai]

I just did a google search to find which pedal it was (because I'm awaiting chips for an Ibanez Flanger) and came up with this http://www.diystompboxes.com/smfforum/index.php?topic=82254.0. Read the edit in the last post. Did this come up in a forum search at all?

[oldschoolanalog]

First try replacing the big power supply cap.
Most likely component to fail.
At 30+ years of age, that should be done anyway.

[R.G.]

First of all, go to http://www.geofex.com and read http://geofex.com/fxdebug/fxdebug.htm picking especially the link http://geofex.com/fxdebug/geriatric.htm.

Once you've done that, ask questions.