If you have dismounted the keyboard in the sense that you left the
circuit board connected to the main board but removed the membrane, do
a continuity test to see if the two halves of the pad are engaged. I
had a keyboard once that had a microscopic connection that caused the
connection to be made.
--- In PolySix@yahoogroups.com, "atuzzi" <antoniotuzzi@...> wrote:
>
> Hi polyfriends,
>
> I decided to help my brother to resurrect his p6...
>
> YEEEEEEkkkk: acid!
>
> Ok you know was completely blocked, everywhere, everything...
>
> action taken the OLDCROW procedure:
>
> 1) removed battery
> 2) removed ic30 and 31
> 3) checked continuity
> 4) recreated dead traces
> 5) new lythium battery with diode in place and no more c40
> 6) new socketed 74ls08 ic30 and ic31
>
>
> status:
>
> A) all digital control are ok (effect type, waveform, sub ecc ecc)
> B) all buttons of the programmer are ok
> C) I can see data changing on TP2 (I have no oscilloscope in place,
> but only a DM and a Logic probe (I'm not in my lab...))
> I can see minimal variation coming out from the comparator (lm393) but
> after that, the data is going in the 8748 (T0 pin 1) and is Missing in
> Action.
> I can see the inhibit working on the 2 4051, that should distribute
> the data on the buffers. But data at the output of the buffers is all
> blocked (all maximum value seems)
>
> D) Key assigner problem:
> every time the p6 is turned on the note #56 (G in last octave) is on
> (GATE 0 is on). I need to switch the arpeggio on and off (or jump to
> unison and back to poly) to turn the note off.
> if an arpeggio is started, that #56 results always on.
> Is not a contact problem (I dismounted the keyboard). So seems another
> IC problem: Does anybody knows the correct logic test to do to
> individuate the faulting IC ?
>
> E) As I have a couple of 8748 and a programmer is the .bin for the p6
> available somewhere ? (I'd like to have a backup for the 2 p6)
>
>
> thank you for your help
>
> antonio
>