Re: [sdiy] Yamaha CS80

[jhaible at debitel.net]

You can indeed get in trouble when you plug the wrong things into Yamaha
CS-synths.

I once plugged a mono cable into the phones output of my CS-50, and
there was a telltale smell of an overheated component. Checked the schemos
and saw that, unlike any other device I've seen before, there was no series
resistor from the HP output amp to the tip and ring connection.

I also tried to use a contemporary Yamaha (!) pedal (FC-7 or FC-9, I don't remember)
into the CS-60 and destroyed the pedal. (Had no time to check what exactly happened).

BUT there is one important point: These synths sound *different* with and without
pedal. This is because the expression pedal is not just a volume pedal; it also
does some filtering (think of "Loudness" correction on old HiFi amplifiers).
And no pedal plugged in is *not* the same as pedal at maximum. At least
it wasn't on my CS-50. I vaguely remember that I have made a correction
in the CS' internal circuit (basically desoldering a capacitor) to fix this
(i.e. to get the "full-pedal" response with no pedal connected), but this
was long ago and I don't have the mod at hand right now. But I'm sure
you will see what I mean when you look at the pedal section in the schematics.

JH.