[sdiy] ESQ-1 battery / main board problem

[Todd Sines]

Here is a video checking the voltages on an ESQ-1
https://vimeo.com/913986230/cafe0467aa

When I boot there is an initial patch of electric piano. I hear when I first start up 3 or 4 notes, but the keyboard is unresponsive. All soft keys on the front panel are unresponsive. The diagnostics state - System Error 01 - soft reset. 

So far I have replaced U39 with a new TL084, CR3 with a new 1n34A ; R15 with a new 1k 1% resistor; tempted to replace CR2 with a 1n34A or 1n270. CR3 measures 131 mV with the unit off; when on I measure 1.342V. 

The service manual states that I should check U14 + U18 V62C64P15L (6264 28pin) RAM; where I get 
Pin 1: NC
Pin 2: 1.314v
Pin 3: 2.721v
Pin 4: 2.797v
Pin 5: 2.712v
Pin 6: 2.66 v
Pin 7: 2.6 v
Pin 8: 1.314v
Pin 9: 2.721v
Pin 10: 2.797v
Pin 11: 2.712v
Pin 12: 2.66 v
Pin 13: 2.6 v
Pin 14: 34mV / 33mV
Pin 15: 2.712v
Pin 16: 2.66 v
Pin 17: 2.6 v
Pin 18: 2.797v
Pin 19: 1.582 v
Pin 20: 3.462v / 4.416 v
Pin 21: 1.84 v
Pin 22: 2.028 v
Pin 23: 1.611 v 
Pin 24: 2.574 v
Pin 25: 2.698 v
Pin 26: 4.844v
Pin 27: 4.032 v 
Pin 28: 4.474v

I really don’t want to replace the main board, I’m wondering if I should start recapping all the 3.3 UF electrolytic capacitors. Has anyone else encountered these issues somewhere along the way I’ve read most of Rainer Buchty’s site, and I cannot seem to find anybody else with this issue.

Thanks,

Todd


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20240217/84b241c3/attachment.htm>