[sdiy] Arp Quartet ADSR issues

[Ben Walker]

> Are you saying that the presence of the keyboard gate voltage is determined by which sound group you select from the front panel?
Yep! And on some sounds the keyboard gate is fed a square wave. That seems intentional, but the low voltage on some sounds less so.

> it's worth looking for physically damaged switches on the panel board and bad solder joints on the connectors.
Good point. And this one is definitely not a museum piece – total rustbucket (and previously modified). The front panel sliders and switches were all crumbling – I’ve replaced most of them but should double check the others, and the general health of solder/connectors around the envelope circuits.

On Sun, 4 Aug 2024, at 11:45 PM, Peter Pearson wrote:
> Those things sound great but they're made of plastic.  Not saying it's your issue, but it's worth looking for physically damaged switches on the panel board and bad solder joints on the connectors.
> 
> On Sun, Aug 4, 2024 at 6:09 PM Adam (synthDIY) <synthdiy at adambaby.com> wrote:
>> 
>> 
>>> On 5 Aug 2024, at 4:58 AM, Ben Walker <ben at audio.computer> wrote:
>>> 
>>> 
>>> The KYBD GATE signal that is sent to the keyboard bus bar sits around +5V for the working sounds, and close to 0V for the others. So there’s no voltage hitting the input pin of the TDA1008, and therefore no output.
>>> 
>> Are you saying that the presence of the keyboard gate voltage is determined by which sound group you select from the front panel?
>> That seems like an odd arrangement!
>> That certainly needs more investigation!
>> A
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