I am having some problems with my ESQ-1


#1

When my Filter “FREQ” parameter is high enough every eighth key I play will skip or just not play. Sometimes it will fizz in or bubble in or there will be a bump sound before or during the note plays or sometimes the eighth note won’t play at all. Turning down the Filter “FREQ” parameter usually gets rid of the problem but I don’t like knowing that there are some sounds I can’t get too. Any ideas on what might be causing this? I have done Filter tuning and everything checked out. (Values were between 146-153.) I have played eight keys with the filter “FREQ” turned down and all the voices seem to be function as in when I press down nine keys the first key cuts out as it should. I have done all the tests that I could from the outside of the synth, everything passed, and have not opened it up yet. Could this be a software problem? The software version is 3.40. I did do a factory reset and it did not help or atleast I don’t think it did. I will be updating that in the future and I do plan to open it up later today or tommorow. I do have a vintage synth repair place near to me and was wondering if any of you could point me toward the problem or even a possible solution. I have been asking around on forums and noone seems to know whats wrong… well actually noone seems to care as I have gotten no replies. The guy I bought it from does except thirty day returns but I would rather not go that route unless repairs seem too expensive. I really like this synth and really want to get it working! Any help would be greatly appreciated! Thank you. :slight_smile:

Here’s a video that demonstrates my problem that I took. https://www.youtube.com/watch?v=HgbGoGjwuSI


#2

Probably a dodgy filter chip or part of the VCF control. There’s a section to the right of the PCB with 8 identical sections, those are the filter chips and associated parts. You might be lucky and they just need reseating.


#3

What is the VCF control and if that is the problem (haven’t opened the ESQ-1 yet) where would it be located on the board?


#4

I meant the digital to analogue control of the VCF. But given it only affects once voice it would seem to be more likely a fault on the VCF chip.

The ESQ-1 schematic scans on the web aren’t very clear unfortunately. The TL081 plays a part in the CV control anyway.


#5

Thanks for your reply! This is actually my first synth and I m a beginner. I will learn a lot when opening this thing. I am a bit of a noob and still don’t understand the VCF filters but I will be checking out the SSM and the CEMs and if those are the problem then it should be a fairly easy fix. If those are not the problem then I will bring it to a local vintage repair place and have them take a look at it. Again. Thank you!


#6

Given it has presets, the analog VCAs and VCFs are under digital control, so there’s a DAC to convert the digital number to a CV voltage level.