Ensoniq ESQ-1 Troubleshooting Help

Hey everyone,

I have an ESQ-1 that powers on but doesn’t make sound and I was told that this would be a good place for some guidance.

The synth worked properly when I first bought it but failed shortly after. I’d taken it to a local shop but they didn’t give me any specifics on what was wrong. Their invoice read “Declined, needs a lot of work”…

Anyway, I heard the people here at Syntaur are Ensoniq experts so I’m looking for a second opinion. I’d like some troubleshooting tips so I can determine exactly what might be wrong because I love the sound of this thing.

These are the issues I know about:
-Low battery warning
-Broken volume switch

The synth had both of these problems when I first got it but it still worked regardless. But after a year in the dark, the synth just wouldn’t make sound again. I was hoping the no sound issue was related to one of these problems but according to the shop I took it to, it wasn’t (though they didn’t give me much to go on).

What process should I follow to determine the issues? I really want to play this thing again.

Sounds like a battery issue youtube will answer all your questions

The battery won’t affect whether it plays or not - it’s only function is to store programs and sequencer data when the ESQ is powered off. You can actually remove the battery completely, and it should still work fine (you just won’t be able to save anything).

By ‘broken volume switch’, do you mean the Volume slider? This is a slide potentiometer (our part #4005) that can potentially preclude it from making sound. It might not actually be the culprit, but if something is broken on it, you’ll want to replace it anyway. Then you’ll be better able to diagnose any further problems.

Yeah, the volume pot is broken. I’ll definitely order the part and try to fix it. Is everything I need to know in the service manual? Also, Ive heard of a few mods that make future battery replacement easier. Do you have any recommendations for anything like that?


I don’t recommend it. For one thing, once you replace the battery, the new one will probably last a decade. And Ensoniq soldered it in to avoid any chance of a disconnect if you hit a pothole on the way to your gig - and arrive to find all of your custom sounds and sequences deleted.

If it were a smaller coin-type battery, putting in a holder would be more practical - the battery is far lighter, and snaps pretty securely into the holder. But the ESQ uses a cylindrical battery that is larger and heavier, and the holders that you can find are less secure. We’ve come across many of these with ‘custom’ battery holders and in many cases, they are flopping around loose inside the keyboard - not only risking the data, but also risking shorting out the electronics.

Thanks for the info! I’ll just stick with the standard battery. I’m a little nervous about opening the synth and doing the repairs myself. Is there a good guide around somewhere for replacing the volume potentiometer?

First, remove the slider caps, by simply pulling upward on them. They fit tightly, so it may help to pry a bit with a flat screwdriver. Don’t push sideways too much - you don’t want to break the shaft off of the slide pot.

Then, here are instructions for opening the keyboard:

Once you get the front panel open, the next step is to remove the display - one ribbon cable, and a few screws.

Then, remove a bunch of screws that hold the panel board in. Once you have this board removed, you can desolder the old slide pot, and solder in the new one. Just be careful not to damage the circuit board traces. You can use solder wick to remove the old solder, then the slide pot comes out easily.

One other tip that will hopefully save a lot of annoyance…

The panel buttons just drop into the holes in the front panel, and are held there by the panel board. If you are working on a flat surface, and let the top panel open all the way, it leans forward enough so that all of those panel buttons stay in place.

If you absent-mindedly tip the panel back when the panel board is removed, all of those buttons fall out, leading to verbal utterances that small children should not hear.

Synth Wizards epidose 4 actually shows the process of opening up an SQ-80 and removing the panel board; it is exactly the same as the ESQ-1, except that on the SQ-80 the display is part of the panel board, and on the ESQ it is a separate part. Anyway, there you can see the whole process:

Sounds like great advice, haha. I’ll keep all of that in mind. And that video’s great! Informative and entertaining. Thanks again!

Hey, if you’re still tracking this forum, I’m curious if you ever got this fixed?

Mainly curious because I’m wondering if an esq-1 stolen from me in Oakland, CA in August of 2017 might have found its way into your hands (not trying to get it back or anything should it be the one… just curious). Having had it for about a year in June of 2018 seems like right around that timeframe, and it had the usual dead battery and a bad volume slider.

If it’s the one I had, the slider worked if you kind of pushed it to the right a bit. I put a piece of cardboard underneath it originally, which put some pressure on it in just the right way to keep the connection, but that patch failed eventually and I needed to just fix the actual slider.

I made a reddit post about that at the time: https://www.reddit.com/r/synthesizers/comments/5lwipu/dont_let_me_fix_your_synths/

If you opened it up and saw a piece of cardboard with a lint roller label inside, it was mine. :slight_smile:

Also would have had some sticker label residue on one of the corners (top right or left, can’t remember) from the shop I bought it from back in 2003 or so.

If you see this, and it was the one, I’d be curious where you bought it from.

Anyhow, hope you got it working again, whether it was the one I used to have or not. Cheers!