Alan Dicker schrieb:
> It could maybe be a Op Amp on that is leaking some timer data in to the
> signel path. Haven't get scimatics or anything in front of me now http://fa.utfs. org/diy/korg_ monopoly/ index.html
> but could be worth checking the outputs on any Op Amp assoctiated with the Arp.
There are two connections from/to the arpeggiator (which is +5V
circuitry) to the OpAmp-World (which is +/-15V circuitry): The
arpeggiator resets the MG1.
MG1 feeds the Arpeggio Trigger in and the Arpeggio-Switche reset the MG1.
Since the signal at the osci is described like an cyclic enabled adress
line, I think the second option should be the suspected one. It might be
worth to interrupt this connection. It is the wire from LFO-Board
connector 6 pin 10 to uP-board connector 23 pin
Btw: this is a modification I'd recommend anyway, if you do not want to
reset the arp-Clock with every new chord, that you play.
> --- On *Wed, 2/12/09, plus_321 /<plus_321@yahoo. com
> From: plus_321 <plus_321@yahoo. com
> Subject: [korg_mono-poly] Re: Mono/Poly doesn't turn on.
> (Transformer gets really hot)
> To: korg_mono-poly@ yahoogroups. com
> Date: Wednesday, 2 December, 2009,
> I tried to use an oscilloscope today to check the power rails. I
> check them on the 356 board, but the seemed fine and I could see any
> significant fluctuations.
> I realize that when I unplug the VCA out connector or power input on
> the VCF board then the noise becomes much louder. So I was able to
> put the scope on the output and see what it looks like. It appears
> to be a constant frequency pulse wave with a small cycle length,
> like 5-10%. The noise doesn't go through the filter so it isn't
> oscillator bleed and it doesn't track the keyboard. The only thing
> that really affects it is moving the arp switches.
> I've found the noise goes away completely if I unplug the arp
> connector from the 356 board, but if I unplug the same cable from
> the other end, the noise remains, but is reduced in volume.
> checked the cable and it seems good.
> So I am thinking that either there is something wrong with my 356
> board that is causing this noise or perhaps their is an issue with
> the cable routing (perhaps maybe it shouldn't be bundled with a
> power cable or something).