[sdiy] Differences between MG-1 filters and broken stuff

[Metrophage]

Here's another difference: most Rogue filters work, but since I
replaced the pots in the MG-1, this filter no longer works!

I love it when an apparently simple repair turns into a complete
debacle. Before, the MG-1 ran at a very quiet volume, but with no sync
switch, and extremely crackly sliders. I replaced all of the sliders
with appropriate values and installed the switch yesterday. Today the
board looked clean and dry, so I started to connect everything again
for bench frenzy. No smoke when I turn it on... the LFO indicator
blinks, but no sound. I went ahead and removed R102 which does result
in the synth being a bit audible, but it's even quieter than it was
before when I had initially gotten it "working"!

The new pots do feel great. The pads are all intact, I made certain
that there are no broken traces from my removal of the old sliders.
What works? The VCOs, LFO, envelope, VCA, noise, ringmod, top-octave
chip. I guess that leaves the VCF section. Resonance does whistle at
higher settings, but I do not hear any filter action. The volume is so
minute that I am not sure I'd hear lowpass filtering anyway.

More tomorrow, must pass out!


		
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