original 70's MXR Distortion + (- output)

[sgmezei]

A buddy gave me his old mxr distortion that someone had previously worked on. I know this person, and would not trust him with a spoon haha.

So, I thought it was cool to see an original one and wanted to post some pics.
As of right now, there is no output when engaged. I have used the test probe and think it might be the red caps on the board. I have no idea how to read the value. Any ideas?

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[jkokura]

You can see the schematic of a Distortion + on this website: http://analogguru.an.ohost.de/193/schematics/Mxr_Distortion+.gif

First off, those look like tantalum caps to me. They're better in a life cycle than electrolytics, so they often got used when polarized caps were needed. It looks to me like you've got one in there between pin 6 of the IC and R7, and another between R3/R4 and ground. Both of them should be 1uF polarized caps. You can replace them with tantalum or electrolytic caps, which ever works better for you.

However, I would suspect the wiring before I suspected those parts. That board and the solder look really solid to me. The thing about these pedals is that they aren't try bypass, so double checking the switch and wiring would be what I would do first.

Are you wanting to restore it? If not, throw a 3PDT in and true bypass that puppy! While you're at it, take the board out and try the 'rock before box' method and eliminate the wiring from being the issue.

Jacob

[sgmezei]

Cool thanks for the tips Jacob. I am planning on putting in the 3pdt and an LED as well as a power jack.

[slimtriggers]

First thing I'd probably do is check the switch for continuity.   Could just be a bad switch

[bigmufffuzzwizz]

If you have a test rig you can apply the connections right to the board and see if you get anything. It's the way I've recently been debugging and works quite well.

[Effectsiation]

...take the board out and try the 'rock before box' method and eliminate the wiring from being the issue.

Jacob,

          Can you describe the "rock before box" method? I tried to look it up but couldn't find anything.



Thanks,
Jake

[k.rock!]

...take the board out and try the 'rock before box' method and eliminate the wiring from being the issue.

Jacob,

          Can you describe the "rock before box" method? I tried to look it up but couldn't find anything.



Thanks,
Jake

hehe! That is the Madbean motto 

Basically it means that you should try wiring your pedal off your box and playing it before boxing it up. You will basically have a board and a whole bunch of wires with 2 jacks and a switch laying out on your desk or floor

Keep in mind that you should ground the sleeves of your in and out jacks to avoid a loud hum when you plug it in.

Feel free to ask more questions if you need help, good luck man!

-Kaleb