----- Original Message -----

From: David Rogoff

To: yamahacs80@...

Sent: Sunday, October 31, 2004 8:15 PM

Subject: [yamahacs80] Channel lights - was Re: Another CS-80 on the overhaul bench

New stuff:

I just added some cool lights to my CS-80.? When tuning the keyboard,
or for troubleshooting, you need to know which voice card is sounding.
There are eight TRG signals that go from the KAS board (which scans
the keyboard) to the M boards (voice cards). I tried driving LEDs
directly from these, but the load lowered the voltage too much.? It
still worked, but I was worried it would be flakey.? So, I copied
(with minor value changes) the same transistor drivers (the CMOS parts
used in the keyboard circuits don't have much power to drive anything)
used on the KAS to drive the TRG lines.? The results are shown in
Photos -> CS80 Renovation -> lights.?

I used tri-color LEDs so that they're green when idle and red when
active.? Because there's nothing blocking the light between the LEDs,
an LED glowing red makes the green ones next to it look a bit orange.
Right now the board is just loose, but I might mount it under the
panel, with the LEDs to the left of the ribbon.? I've also thought of
adding some LEDs for the PWM rates, the ring mod rate, and the LFO rate.

One more thing:? the CS-80 service manual came with great, huge,
fold-out schematics and block diagrams for the whole unit.? There are
very good scans of these on synthfool at
and
? I tried printing
these out in parts and taping them together, but it was a big pain and
didn't line up.? Last week I just popped the files on a CDR, went to
Kinkos, and had them both printed on their large-format
black-and-white printer.? For both of them printed about 3 x 6 feet it
cost $16.? Great wall posters and invaluable for tracking down problems!

David