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  • July 29, 2019 at 2:41 am in reply to: HEELLPP!!! Original PolyChorus Issues #125408
    vinxs
    Member

    OK!!

    Changed out the x2 electrolytic and x3 tantalum caps, and replaced all the wires. [strong][/strong]

    Ive noticed some improvement, that violent random abrupt distortion sound has gone which I’m wrapped about, but the general volume drop when the effect is activated is still significant, i can hear the modulation very faint , the drop is even more apparent when the “Blend” Switch is ON.[strong][/strong]

    You were quite right with the moving voltage on the LM324 chip, (pin labeled 1.6v was ramping up and down between 6.5-8.2)[strong][/strong]

    Im in the process of making an audio probe, what would you suggest i try next pal? replace the “NE571N”?[strong][/strong]

    July 21, 2019 at 3:20 pm in reply to: HEELLPP!!! Original PolyChorus Issues #125400
    vinxs
    Member
    Quote:
    Be very cautious with the 2 SAD1024A, they are fragile and the slightest short will burn them. I own the same pedal, it only had one trouble 2 years after purchase, circa 1982, one of the SAD1024A died -the pedal had no sound- I replaced it (they were cheap at that time now they are out of price) it still works fine now. It is my favourite chorus pedal and I have a lot.

    Cheers Frandid, yeah im very cautious of them, thanks for your reply ;)

    July 17, 2019 at 4:31 pm in reply to: HEELLPP!!! Original PolyChorus Issues #125393
    vinxs
    Member

    Ahh great!! good thing i confirmed with you.

    Yep familiar with the polarity caution with the axial caps ;)

    thanks mate ;)

    July 17, 2019 at 1:00 pm in reply to: HEELLPP!!! Original PolyChorus Issues #125391
    vinxs
    Member
    Quote:
    Without checking the schematic I can already tell you, your LM324 should have some moving voltages on it and the voltages on half your 571 are way off.

    My suggestion would be to start by just replacing all the electrolytic and tantalum capacitors first of all (unless you want to individually test them, but I wouldn’t personally bother), they’re probably 40 years old by now and they’re the most common issue I find in repairing old EHX.

    Good news is that your clock and SAD voltages look good.

    Scruffie, when you say change out the “tantalum capacitors” does that include the greenies? or just the x2 blue and x2 brown ones roughly in the center of the board?

    Electrolytic im guessing the grey littlie barrels and the x2 blue bigger barrels.

    p.s does this ceramic one physically look ok to you?…

    cheers pal!

    July 15, 2019 at 5:42 pm in reply to: HEELLPP!!! Original PolyChorus Issues #125384
    vinxs
    Member

    Thanks Pal !!!

    I cant begin to thank you enough!!!

    thats great news about the SAD1024’s .

    Knowing that, its given me confidence to spend more time on it replacing the caps ;)

    Cheers !!

    July 14, 2019 at 3:19 pm in reply to: HEELLPP!!! Original PolyChorus Issues #125381
    vinxs
    Member
    Quote:
    https://www.dropbox.com/s/r7bd9b4qhiuy67e/EH7700-E.jpg?dl=0
    July 17, 2016 at 4:58 pm in reply to: 70’s BigMUFF Crying Tone Wah , Replacement Mode Switch #121735
    vinxs
    Member

    Sure does ;)

    Thanks for that, out of curiosity could you send me a link to the schematic, all the ones I’ve purchased seem to be a different model.

    My board is the EH-5600 and looks like this…

    June 28, 2016 at 8:07 pm in reply to: HEELLPP!!! Original PolyChorus Issues #121688
    vinxs
    Member

    Thanks Scruffie,

    I do have an oscilloscope, but im still learning how to operate it, thanks so much for your advice, im going to take it to a pedal repair guy down here in Melbourne, hopefully he will be able to adjust it ;)

    Cheers

    June 28, 2016 at 7:40 pm in reply to: HEELLPP!!! Original PolyChorus Issues #121684
    vinxs
    Member

    OK, being unfamiliar of where to test the voltage points,
    i checked all the solder joints to find a few loose ones, after re-soldering them that crackling sound stopped. ;)

    However, when i engage the footswitch i notice a significant drop in volume compared to the bypass mode(OFF), (with the Blend in the OFF position, Blend in the ON volume is of matched level.

    Is this normal behaviour on these old pedals?
    Or a common fault perhaps?

    Anymore info on this would be greatly appreciated :P

    Cheers

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