[sdiy] Ensoniq Esq-1 main board question

[Mark G]

Hi, I have an Ensoniq ESQ-1 (metal case) that has decided it no longer wants to turn on, it shows a brief flicker on the display but that's it, no sound, no display, no response to any buttons. I went through the service manual, and verified that the display self test works, and the power supply voltages are all good. Performed the hard reset with no results. Tried reseating the socketed chips and cable connections, nothing.  The manual at this point is no help, as it just instructs you to replace the main board.  I acquired copies of the schematics from buchty.net, but the ones of the main board circuits are not great quality so some things are hard to read, which makes troubleshooting more difficult. 
 Does anyone have any knowledge of common main board issues that I can check, or any tips?  I'd prefer to repair the board that I have if possible, especially since replacements seem to be hard to come by. Any help would be greatly appreciated!
Thanks,
Mark 
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