Hello Malte,
Hi Andy,
I am the forum member Andrew mentioned yesterday. I'm not sure it could help you a lot but here is a description of my symptoms :
Here is a video taken few days ago. At this time, my P6 had been powered up for 3 hours or so :
http://demo.ovh.com/fr/40fbff223d8eac6917e9a7018648dd47/Usually the PROGRAM LEDs didn't blink like that. It only happened 3 or 4 times.
But I've very often experienced a switch back to A1, after 2-5 minutes. The alternative was three PROGRAM LEDs lit at the same time.
All the patches stored in RAM had troubles :
- most of them seemed like empty or silent
- some others were working but sounded raw or corrupted
After I had made a new D/A adjustment I had more or less the same proportion of "empty" and "corrupted" patches. But not at the same location. For example, if A3 was previously sounding raw or corrupted and A8 was silent, after the new D/A adjustment A3 was silent and A8 was sounding corrupted or raw.
I also noticed the RELEASE to behave strangely, and the MG too.
One last thing : the ATTENUATOR knob didn't produce the expected result. For instance, switching from +10 to +8 or +6 actually made the output sound louderÂ…
Good luck !
--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> Interestingly I have board with the very same problem which I constructed
> for another forum member. The guy is kindly sending it back me me after a
> vast amount of remote debugging. From what we found and saw looks like the
> CPU or closely associated components may be at fault. If you can wait for a
> week or so I shall have this rogue board back in the lab for analysis. Also,
> strangely enough, removing the RAM for this board had no bearing on the
> problem whatsoever, but removing the comparator (IC6) which handles the data
> in from the control panel mux and the feedback from the D/A convert
> completely eradicates the instability! You might want to try this with your
> board and report back what happens. The only caveat is that you can use the
> control panel!
>
> Let me know what you find.
>
> Cheers,
> Andy
>
>
> On 26/08/2010 14:01, "Malte Rogacki" <gacki@...> wrote:
>
> >
> >
> >
> >
> >
> > So I managed to complete my first replacement PCB.
> >
> > Things don't look too bad but it has a number (?) of problems that are a
> > bit difficult to debug for me.
> >
> > Basically it runs somewhat unstable. Occasionally it will more or less
> > reset itself or will exhibit some other behaviour which will explain in a
> > second.
> >
> > Nearly all chips are new, except processor, LM13600's and RAM. All
> > functionality is there; calibration was more or less successful. I haven't
> > yet a battery installed.
> >
> > THe most common symptom at the moment is that some LED's on the KLM371
> > start to blink or that a number of LED's light up permanently (and others
> > get turned off). This has happened with different KLM371's so I suspect the
> > error to reside on the KLM367. Oddly enough often the sound isn't affected
> > at all initially and the switches still work fine. I can call up other
> > programs and other banks.
> >
> > Sometimes shortly (or several seconds after this) the LFO modulation is
> > turned off (I have programmed this particular test sound to modulate the
> > VCF). There might some other parameters change slightly as well; I have not
> > yet narrowed this down completely. Sliding the LFO switch back and forth
> > restores the modulation; so the actual LFO depth isn't affected, just the
> > target.
> >
> > So, it appears to me (grain of salt...) that the parameters controlled by
> > IC28/29/34/35 may be affected, but not the ones controlled by IC18/19
> > (post-DAC).
> > This and the working switches leads me so far to the conclusion that the
> > data lines D0 to D7 may not be the culprit here and that the problem could
> > be related to lines P24 to P27.
> >
> > Could this be another "bad RAM" issue? My first salvaged RAM was definitely
> > dead; it wouldn't store anything. The current one seems to work as far as
> > storing goes.
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>