Discussion about the Korg PolySix synthesizer

Must be. I was quite surprised when it dropped out. Thanks for the direction. I'll keep looking a report back.

Cheers everyone




--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> Hi,
> 
> If you are certain you have performed the reset procedure (with the 56K
> resistor) and the A/D convertor calibration then you should definitely be
> re-examining data bus lines DO0 thru DO8. The logic here will determine the
> LED and switch assignments (amongst other things). Even if you have spent
> time performing cold resistance checks it would to worth using a logic probe
> (one which can be used to look for pulse trains) at either end of the data
> bus to ensure you have the appropriate logic when you view and operate the
> patch assignment keys and LEDs. For example start on the KLM 371, obtain a
> datasheet for the 72LS75 and study the truth tables for these devices. Try
> operating some of the buttons and see how the logic decodes. It is a bit of
> a grind, I am afraid, but I feel certain that you still have a one or more
> intermittent open circuit tracks.
> 
> Cheers,
> Andy
> 
> 
> On 08/01/2010 21:20, "ML" <f115@...> wrote:
> 
> >  
> >  
> >  
> >    
> > 
> > Did nothing.
> > 
> > --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , "ML"
> > <f115@> wrote:
> >> >
> >> > Thanks! I'll do that and see what happens.
> >> > 
> >> > 
> >> > 
> >> > --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> ,
> >> Johannes Hausensteiner <johau@> wrote:
> >>> > >
> >>> > > Do the Reset adjustment.
> >>> > > 
> >>> > > ML wrote:
> >>>> > > > With my first polysix tuned up I started to set my sights on a second
> >>>> P6 I have here. This one is a recovery project i picked up.
> >>>> > > >
> >>>> > > > It has a handful of problems. The main issue is that it doesn't allow
> >>>> patches to be switched. It stays locked on one patch and multiple Patch and
> >>>> bank LEDs are lit. It also has the same problem with the MG as my first one
> >>>> did. It intermittently tiggers the maximum MG level.
> >>>> > > >
> >>>> > > > I started looking at it more carefully. It actually had a cold solder
> >>>> joint on one of the MG level pins but fixing that didn't repair the
> >>>> problem. This P6 needed the battery mod done too. I installed that and then
> >>>> replaced IC30 and IC31. For a very short while I managed to recover the
> >>>> bank, patch, and write functionality but somewhere during this process it
> >>>> died again and is back to running one patch and multiple bank / patch LEDs.
> >>>> I'm quite certain I covered all the traces properly because I even had to
> >>>> add a few wires to connect points and the corrosion isn't major on this
> >>>> card. Do you have any suggestions on other ICs that may need inspection?
> >>>> > > >
> >>>> > > > Also - it would be great to understand the board better. Does anyone
> >>>> mind elaborating on the specific tasks some of these ICs have?
> >>>> > > >
> >>>> > > >
> >>>> > > >
> >>>> > > > ------------------------------------
> >>>> > > >
> >>>> > > > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6Yahoo!
> >>>> Groups Links
> >>>> > > >
> >>>> > > >
> >>>> > > >
> >>> > >
> >> >
> > 
> >  
> >    
> > 
> > 
> 
> 
> 
> [Non-text portions of this message have been removed]
>