[sdiy] ESQ-1 battery / main board problem

[Rutger Vlek]

My first question, especially in the case of the ESQ1 would be: how is the
PSU? Stable, within specs? Second: any info on how the problem emerged?
Suddenly? After years of storage? Etc?

Rutger

Op za 17 feb. 2024 17:51 schreef Todd Sines via Synth-diy <
synth-diy at synth-diy.org>:

> 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
>
>
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