MXR 117 Flanger help

[slimtriggers]

Sorry if this is the wrong place to post this, but I need some advice with this pedal.   

I have a 1978 MXR flanger, it's one of my most prized pedals.  Anyway, it recently started producing static that almost completely drowns out the signal.  If I turn the pots, I can hear the effect on the static, but the guitar signal is very, very faint under the sound of white noise.

My first inclination is to replace the power filtering cap. 

Any other guesses or suggestions?

Once again, I apologize if I should not have posted this here. 

[jkokura]

Open it up and let us have a look. That will do lots to help us help you. Plus, we like the pedal pron anyway.

Is that the old MXR unit with the built in Power cord? Be careful in there...

Jacob

[slimtriggers]

OK, here's the pron    I'm not the best photographer.  I can never get really good macro shots.

The cap in question is the 25v 400μF Sprague.  In researching the problem, I'm finding reports of that cap drying up over time and causing various noise problems.  It looks like it would be a fairly simple job to replace it, at least. 

Thanks for your help

I had to re-size these and they're still pretty big.  LOL

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[slimtriggers]

cap

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[slimtriggers]

pots

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[slimtriggers]

I found what I think is the schematic for this one, too.



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[stecykmi]

The filter cap is a good bet but the only way to say for sure what's wrong is to trace the signal along and see where the noise originates.

[jkokura]

There's a bunch of oxidization on a few of the parts as well. Perhaps you should try carefully cleaning some of that up a bit and see if any parts have become damaged or need replacing! It may be possible that it's as simple as replacing that filter cap, but it might be the regulator, or some other cap that's become leaky or faulty.

Be really careful with that Reticon IC. It's what's valuable in that circuit....

Jacob

[slimtriggers]

Thanks for the suggestions guys!  I think I'll start by replacing that cap.  That will be pretty quick and easy.  If that doesn't work, then I'll move on to the audio probe

I'll stay well away from that IC for now, too.

[jkokura]

If it's socketed (looks like it might be), you could try removing it before working on the pedal.

Jacob

[slimtriggers]

Woohoo!   It was the cap!  I replaced it with a 470μF 35v cap and it's as good as new!

Thanks for the help and suggestions! 

I was worried about even messing with that IC at all-those are nearly $100 from what I've seen  

[maysink]

Now that you've brought it back from the dead I bet it's REALLY a favorite pedal! I confess to having a weakness for flangers and that one looks like a beauty.

[slimtriggers]

It's definitely going to get a lot more use!  I was blown away by it when I first heard it years ago.  It can get a nice, organic, lush flanging sound, or it can get that weird "playing in a tin can" effect-and lots of interesting points in between!

I got it for $15 at a pawn shop back in the 80's.  One of those lucky finds.  As long as I can keep it alive, it will always have a spot on my board