Yamaha CS80

Someone asked for the schematic of the LED driver.  I did one up and
stuck it in the folder with the other LED pictures (Photos -> CS80
Renovation -> lights).  The resistor values aren't that critical -
they're just the closest Radio Shack had to the ones already used on
the KAS.  The transistors are generic PNPs that Radio Shack sells 15
for $2.60 (part # 276-1604).  The little proto-board (with box) was
also from RS (# 270-283).  Oh - and the 47k in series with the LED is
supposed to be 470 ohm.

 David


--- In yamahacs80@yahoogroups.com, <barbara_Streisand@h...> wrote:
> Great thanks for the files!!!
> best david
>   ----- Original Message ----- 
>   From: David Rogoff 
>   To: yamahacs80@yahoogroups.com 
>   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
>   http://www.synthfool.com/schematics/cs80_1.jpg and
>   http://www.synthfool.com/schematics/cs80_2.jpg.  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
> 
> 
> 
> 
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