Problems building FC Monograf

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mightycoco
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Problems building FC Monograf

Post by mightycoco » Tue Jan 26, 2021 4:13 am

Hi Guys,

I'm having problems getting the Monograf DIY running. VCA/VCF/ADSR seem to work when measuring but the VCO doesn't swing.
I could track it down to pin 15 of the AS3340 doesn't get voltage. But there are a lot of mod sources and I can't trace back, where the normalized and external voltage should come from.

I couldn't find any schema to trace back pin 15 which makes debugging even more complicated.

The AS3340 does get power, and if I connect a DC source of some volts directly to pin 15 I get audio.

Does anyone has a schema or knows, which pins going from controller board to the core board I should check?

thanks,
MC

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Agawell
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Re: Problems building FC Monograf

Post by Agawell » Tue Jan 26, 2021 11:21 am

have you considered sending FC an email? - they are quite helpful - maybe they have a schematic
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nigel
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Re: Problems building FC Monograf

Post by nigel » Tue Jan 26, 2021 3:30 pm

mightycoco wrote:
Tue Jan 26, 2021 4:13 am
I could track it down to pin 15 of the AS3340 doesn't get voltage. But there are a lot of mod sources and I can't trace back, where the normalized and external voltage should come from.
Pin 15 is a virtual ground pin, so it's always going to be at the same voltage (probably 0V) when it's working correctly.

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DJMaytag
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Re: Problems building FC Monograf

Post by DJMaytag » Wed Mar 03, 2021 5:43 pm

I'm about to finish building this one, and I'm curious the pad on the ground pin for the V/oct jack. It looks VERY close to the other pad, in a similar way that I had an issue with a jacked grounded/shorted on a Stasis Leak build. Have you double checked continuity on all your jacks, to be sure nothing is shorted out?
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DJMaytag
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Re: Problems building FC Monograf

Post by DJMaytag » Wed Mar 03, 2021 10:11 pm

I got mine up and running, and everything seems to be fine so far. Have you noticed anything else odd about it yet?
Instagram | Soundcloud | MG Main Rack 6U+6U

If you talk about improper grounding 3 times, Graham Hinton appears!” -djs

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