EHX Memory Boy - not working

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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Rebuilder
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Post by Rebuilder »

Hi guys,
I was just reading a lot of topics and I'm looking for clues to repair my EHX Memory Boy.
It was stored for some years, and now i can't get any effect out of the pedal, i already tried battery, and AC, and the behavior its the same, i can turn it on and off, i have sound, but no effect...
Delay and Depht doesn't affect the sound and blend and feedback just do some type off modulation turning the sound imperceptible.

Anyone can help me with this one?

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Post by Rebuilder »

Meanwhile, a little update...
I read that the pedal have some kind of internal clock and some test points. So i made myself an audio Probe, to check those spots.
I don't have any experience with probes, and internal clocks.
I realized that all the points that i checked, i can listen the "beep", but i also saw that when checking the I/O in some chips, and in random points, the intensity of that signal its different, and sometimes the beep are different too...

Any of you guys know if thats normal?

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brujo
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Post by brujo »

You need an oscilloscope, inject signal in the input jack and start probing the test points labeled TP in the board. Every TP should have signal present, so if you don't get a signal on any test point move the associated trimpot slowly until it appears, the BBD's have a sweet spot to work, and pass no signal in the other points. When you get signal present on all test points connect your guitar and test the effect.
You can fine tune the distortion and tone of the repeats using all trimpots, . Make the delay oscillate and turn the trimpots slighty to get some clipping.

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