Prodigy fault

Toris · Post by **Toris** » Thu Oct 26, 2006 8:48 pm

My Prodigy has just developed a fault. When the 'Release' switch is switched on, the pitch of any note played dies steadily during the release time. If the release time is increased the pitch drops at a slower rate but still proportionally with the release time. If the 'Release' switch is set to off, the sustain part of the envelope manages to hold the pitch perfectly.

Anyone have any ideas if this sounds like a straightforward repair or am I sending it off to a tech?

Cheers in advance

Toris · Post by **Toris** » Thu Oct 26, 2006 9:08 pm

I've made some progress. Schematics and circuit description here:

http://www.hylander.com/moogschematics.html

According to the write up, C21 and U12A 'hold' the last pitch voltage when any key is released. Does that mean I should replace both of these?

Post by **Maschinengeist** » Fri Oct 27, 2006 5:21 am

I've located the C21 capacitor in the Modulation circuitry and U12a IC is in the Filter KYBD Control circuitry... Unfortunately, I can't identify the much from the schamatics scan. I'll have to read the text torrow (too tired tonight) and see what Bob has to say on this.

Have you asked Dougt? He sure has his say on this.

dougt · Post by **dougt** » Fri Oct 27, 2006 6:38 am

Yes, try replacing U12 (LF353 opamp in the sample & hold section)... Also make sure all the keyboard contacts are making a good connection when playing and releasing each key...

Toris · Post by **Toris** » Fri Oct 27, 2006 8:45 am

Cheers fellas. Sorry for the delay in replying (I had to go to bed!). Left the Prodigy on all night, tried it this morning and all is well???

I'll still replace U12 and what about the cap? Do you think it's taking a bit longer to charge or am I talking bollocks?

I'll also clean the key contacts over the weekend if I get a chance.

Better scan of the schematic on bluesynths

http://www.bluesynths.com/modules.php?n ... rop=filter

Thanks, as always, chaps for your ongoing help

Toris · Post by **Toris** » Mon Oct 30, 2006 9:32 am

Found some time to mess around with the Prodigy over the weekend. I re-soldered all of the front panel pots and switches to the PCB, cleaned all the internal connectors and cleaned the key contacts and it seems to be OK, providing I'm nice to it and whisper sweet nothings into it's output jack.

I have picked up a couple of double triggering keys which I need to sort.

I'm not which design 'engineer' had the bright idea of soldering the pots direct to the PCB then poking them through holes on the fascia with no mechanical support or locking rings? Hindsight's a wonderful thing but so is common sense, no wonder Bob denied all knowledge of the Prodigy.

It's no big deal to be honest, it never gets used live and just lies around the studio looking nice.

Thanks again for the help people