[sdiy] ESQ-1 battery / main board problem

[Rutger Vlek]

Additionally, based on my own experiences with ESQ1: the CMOS multiplexers
are from the famous period where quality issues occurred. In my own ESQ1
they intermittently could lock up in one state, as a consequence. Might
even cause the CPU to halt, which I believe is what might be happening in
your case.

Rutger

Op vr 23 feb. 2024 08:21 schreef Rutger Vlek <rutgervlek at gmail.com>:

> 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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