Yamaha CS80

Is the waveshape chip very sensitive to heat when desoldering???

It is of course, one of the chips without an IC socket............

could it be socket mounted once out or would a socket create more
problems???
-----Original message-----
From: David Rogoff david@...
Date: Wed, 02 Apr 2008 20:26:34 -0700
To: yamahacs80@yahoogroups.com
Subject: Re: [yamahacs80] I need 2 M cards

slammah2006 wrote:
> I am down 2 Oscillator cards in Bank 2 (# 3 and # 5) I believe it is

> the Waveshape chips that are faulty.....
> Does anyone have any spares,
Good luck
> or is know if there is a way to drop a 
> voice out of the rotation giving 2 banks of 7 Oscillators???...If
that 
> were the case I could move one from my first bank to bank 2...
> 
This is pretty easy - I've done it before for someone while waiting
for 
an oscillator chip. Move the bad parts to the highestvoice cards (e.g.

voice 8, then 7). Then you just jumper on the KAS board. If you look
at 
the KAS chip description 
(http://www.therogoffs.com/cs80/manuals/CS80_Service_Manual/06%20-%20KAS%20ICs.jpg),

you can see that changing pin 40 (MODE) from -6.5 to +8.5v skips voice

8. If you have to disable more voices, then you need to change the 
K01-K08 pins. Look at the difference between the CS80 KAS board 
(http://www.therogoffs.com/cs80/manuals/CS80_Service_Manual/04%20-%20KAS%20schematic.jpg)

and the CS80 KAS board (page 3 of 
http://www.therogoffs.com/cs80/manuals/CS50_Service_Manual/Yamaha%20CS-50%20Service%20Manual%202%20of%202%20(%2011%20x%2017%20-%20Double%20Sided%20).PDF).

Note: when I did this, I just changed the MODE pin (by cutting the far

end of the resistor attached to it and connecting it to +8.5v) and 
didn't tie the K08 pin. This caused the 8th voice to be on all the
time 
and screwed up thetrigger to the Ring-Mod EG. I ended up pulling the 
oscillator chips on the 8th voice M Cards to mute them. However, this 
created a really weird side-effect. The waveshaper chip was still
there 
and picked up the signal from the PWM oscillator. When the PWM rate
was 
raised, it triggered the WSC and the oscillator was audible all the 
time! Confused the hell out of me at the time.

David




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