Dead Ensoniq ESQ-1

Hello everyone,

I picked up an ESQ-1 recently that won’t power up.
I haven’t started testing anything yet however I did plug the mono out into an amplifier and when I turn the power switch onto the ESQ-1 you can hear the pop through the amplifier.
Nothing appears on the screen and no sound comes out even when messing with parameters.
I’m wondering if there is a known issue that this description fits?
The synthesizer is extremely clean and was very well taken care of.
Any suggestions on where to start with this?
Any help will be very much appreciated!

Usually when the entire synth is dead it indicates a problem with the power supply. The best place to start would be checking the power supply lines for the proper voltages. Since it’s a synth from almost 40 years ago there’s a good chance some of the electrolytic capacitors in the power supply have failed or are showing signs of age and they will need replacement. Often you’re able to visually expect them for signs of leakage or bulging but they can fail more subtly too. The leakage will typically be from the top of the capacitors; if you see any strange looking goo at the bottom of large capacitors that is a glue that manufactures use the secure the capacitors.

After replacing the capacitors if you still aren’t reading the proper voltages you may have other failed components, the voltage regulators in these old synths are also prone to failure in some power supply designs.

Always be very careful when working on power supplies, especially on the line voltage (AC wall input) side of things. Never touch anything with the synth plugged in, only use your multimeter probes. Always wait a moment after powering off before touching anything (large caps can store some charge and give you a small zap, waiting 10-20 seconds is more than adequate).

Hope you can get it up and running!

Thank you so much for the great advise!
I’m going to follow it and I’ll update soon.