Home › Forums › Vintage EHX › Vintage Deluxe Electric Mistress – No Sound When Footswitch is Pressed

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  • August 7, 2020 at 3:59 am #86385
    louloomis
    Participant

    Hey Everyone,

    In brief:

    I have a vintage Deluxe Electric Mistress with the 2 prong AC cable. It is V3 and the board inside is a D board.

    I get unaffected sound when I don’t press the footswitch, and when I do press the footswitch, I get nothing. This is with the cable from my amp plugged into the “Flanged” output.

    I have looked at Ralf Metzger’s page, but I’m trying to just sanity check before taking on the task of checking pins/sockets, etc.

    If I attach my multimeter to each of the plug’s two blades on the end of the power cord that goes into the wall, I get a reading of about 550 ohms. Is my power transformer working?

    Other issues:

    1. Inside I see that there is no solder (and no solder pads) where the leftmost two pins are for the chip that’s in the upper left of the board near the Filter switch. Are these pins actually supposed to be connected to a part of the circuitboard trace? I only see a small trace near the upper pin, but the bottom pin doesn’t seem to be connected to anything.

    2. I did some sanity checking on the footswitch and I am fairly certain it works. It seems like it was wired incorrectly based on pictures I’ve seen of other circuit boards, so I fixed that. However, it still didn’t produce any sound.

    Any direction of how to see if it’s a big or small issue would be great. Again, just trying to sanity check to see what I’m dealing with.

    FYI – I tried to upload photos but the size limitations makes them too small to be useful I think.

    Thanks.
    LL

    August 7, 2020 at 9:25 am #126341
    The EH Man
    Moderator

    You should probably send it to a tech. Sounds like it could be a power supply issue or a bad component.

    August 7, 2020 at 10:15 pm #126342
    louloomis
    Participant
    Quote:
    You should probably send it to a tech. Sounds like it could be a power supply issue or a bad component.

    Thanks for the reply.

    Full disclosure: I am a bit puzzled by your feedback. My question reads like “I want to make sure I don’t need to call a plumber. Maybe there is something I just need plumbing tape for or a pipe wrench?” but your response was akin to “Call a plumber. Your issue may have something to do with pipes and/or water”.

    I’m just a bit puzzled in terms of why this was your response.

    LL

    August 7, 2020 at 10:20 pm #126343
    The EH Man
    Moderator

    If you have no idea about electronics you’d be better off sending it to someone who does.

    August 7, 2020 at 11:52 pm #126344
    louloomis
    Participant
    Quote:
    If you have no idea about electronics you’d be better off sending it to someone who does.

    I understand. To date, I have repaired probaby about 10-15 different pedals from different manufacturers with varying issues and maybe about 4 guitar amps. So, I have some electronics knowledge…but it is limited for sure. However, I am a technical person.

    Therefore, just like anyone else, my objective in posting my questions here was to see if someone could share their knowledge with me and maybe get me on the right track. I’ve had positive experiences asking questions of this type in every other forum I’ve posted in before. However, if this forum is not that kind of place, that’s fine, too.

    LL

    August 19, 2020 at 10:19 pm #126365
    BigBox
    Participant

    Hi LouLomis, I read your post. As someone who took up analog electronics repair as a hobby a few years a go, I can tell you it is extremely challenging repairing 40+ year old electronics, and you should make sure you have everything in place before you begin. This includes having quality repair and diagnostic equipment, including a good soldering iron, de-soldering tools (pump and/or wick), a high quality multimeter and oscilloscope. Next, make sure you understand how to read electronic schematics.

    For the Electric Mistress, we are all fortunate for Ralph’s website which provide schematics of all the different versions, as well as photos. These should be sufficient for you to answer question #1, even though I must confess that I’m not quite sure of what you mean by “pins” and “chips”. If by chip you mean the IC, I would make sure you identify which part it is specifically (i.e., 4558) so that other people understand.

    For me, the most puzzling comment is when you measured the resistance of the two prong cord. First off, I have no idea where these measurements were recorded. But more importantly, this is a meaningless measurement. Outside of checking to make sure your have the right resistor in place, resistance is rarely measure when troubleshooting. You want to focus on voltage. The prongs deliver 120V (or 240V) of alternating voltage to the step down transformer, which then gives off 32 V that passes through the power diodes that feeds 18V (half the wave) into the linear voltage regulator which gives the end result of 15V of steady DC voltage which powers the circuit. My experience is that these linear voltage regulators are commonly fried and need to be replaced, especially after all these years.

    Regardless, you need to use your multimeter to look at voltages throughout the circuit. There are so many possibilities that can cause you to get no sound.

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