OldSynths

--- In oldsynths@yahoogroups.com, "sgtgunn" <samrixey@...> wrote:
>
> I purchased the DK600 for $50 at a small shop almost a year ago, and
> determining that the backup battery was fine (I actually just removed
> it for safety's sake), everything seemed to work fine except the panel
> buttons (all knobs work perfectly). Here's what I figured out:
> 
> Every time a button is pressed, the synth resets. Resets to what? I'm
> not sure if it's a preset or not: a slow attack, a fast LFO, and a lot
> of the Noise turned up. There is a "button" on the main PCB for a
> manual reset. If you've seen it, it is just two points that you use a
> multimeter in diode mode to connect. This resets the synth exactly as
> if I had pressed a button. 
> 
> What I'm thinking is that anytime a button is pressed it is somehow
> traveling to the CPU chip (IC1) and a signal is sent to pin 14 which
> triggers the reset (I'm sure this is an oversimplification, but this
> is what I'm picturing in my head).
> 
> What do you think? If Analog/Digital hybrids aren't really discussed
> here, just let me know :)
> 
> Sam
>

 Hi'ya Sam!

 Best Bet: disconnect the reset pin on the CPU and see what happens
next. I'd bet that either: A.) you have a grounding problem with the
pushbutton controls and the commands are coming up glitched or scrambled.

 When this happens, a lot of times programmers will have had the good
sense to put a 'sanity checking' subroutine in, a series of
if-then-else statements if you like - everything that isn't dispatched
properly leads to a reset. Check for proper grounding with those switches.

 The other alternative B: is that this synth might have a scratchpad
memory that must be kept alive with the backup battery. Usually such
memory is loaded up at the time of power-on-clear, when the system
initializes. 

 Unfortunately one of the nasty tricks that has happened in times
past, was the factory would load that scratchpad and assume
that when the backup battery failed, the unit would be rendered 
inoperable, and you would return for a new battery! AND a scratchpad
reload! 

 Don't laugh! I had a $1500 ICOM ham transceiver that went down this
way. The trick is to add a few clip leads with another battery, THEN
change the backup cell such that power is always maintained. (sneaky!)

 I sincerely hope it's just A and not B. 

 Cheers!
 -Erik