Hi Wayne,
> I am thinking that the problem lies in the output part
> of the DeMux and was curious what the relevant CMOS
> chips were for the signals that aren't showing up.
I'll take it you haven't seen the schematic for this board? The CMOS
logic types are clearly marked on the diagram. If you don't have it
we can easily point you in the right direction of a copy. Some of the
problems you mention are in the area of the IC19 (4051), but some are
mearly switch functions and under control of the latches IC28/9 and
IC34/5 (4042). Therefore I would suggest that you check the
continutity of the tracks running from the mask rom (8048) P20-P27
and the memory address bus DO0-DO7. Pay particular attention to port
line P25 as it runs directly under were the battery has exploded. I
find the best way to perform continutity tests is to print out the
diagram and mark off the areas of track checked with a highlighter
marker. If you want any comparative voltage / scoep waveform reading
let us know.
Let us know how you get on and if you still can't get anywhere then
see post 1934.
Cheers,
Andy
--- In PolySix@yahoogroups.com, Wayne Griffin <ingsoc_1979@...> wrote:
>
> I've been trying to help my friend repair his P6 which
> was the victim of nicad leaks once again.
>
> I've carefully replaced and verified all of the traces
> but I'm still having an interesting problem.
>
> The ENV and VCF controls behave normally.
>
> However, there is no response from:
> OCT
> WAVEFORM
> PW/PWM
> SUB OCT
> LFO MOD
> FX MODE
> SPEED/INTENSITY
>
> I am thinking that the problem lies in the output part
> of the DeMux and was curious what the relevant CMOS
> chips were for the signals that aren't showing up.
>
> cheers! [w]
>