Service woes - Siel dk600

[Greg Montalbano]

>Unfortunately my dk-600 is also faulty. I received it with all working
>except for the patch memory. I opened it up and noticed the leaking battery.
>I cleaned it up, replaced battery, repaired traces, cleaned all socketed
>IC's and jumper connectors however it still has the same problem: the
>patches can be played manually and stored in memory however when they are
>recalled, they sound correct however there are random snaps of loud static
>bursts. It seems like the Res is going from it's setting to 100% then back
>to normal again within a few ms. I thought it may be the knob reading
>circuitry however it seems to work in manual mode (which is how I run it).
>
>The other problem is that you can not calibrate the cutoff freq. Six voices
>can be calibrated for the cutoff slider but once you add kbd track it goes
>out again. Likewise if you calibrate it for slider and keytrack, assigning
>envelope knocks the cutoff out of wack again! 

I don't think that's a battery/RAM problem;  both of these symptoms sound
like the infamous "random data/control interaction" problem that was
plaguing my dk600 (and a lot of others I've heard about, since I originally
posted this problem).

The solution in my case was to painstakingly clean (with some kind of
isopropanol-type contact cleaner) ALL of the ribbon cable connector points
& sockets-- these connectors being generally agreed to be the cause of most
dk600 problems.  I also had an intermittently faulty IC9 (74LS154) -- this
chip is vital to many functions in the synth, including the timing of the
control board interface.

~G~