[sdiy] Korg Polysix major problems - Update

[Ullrich Peter]

Hallo Karl!

It seems that you could use a new programmed 8748 or 8749 microcontroller.
As you are from Sweden as your emailaddress tells me you may be interested
in getting a new microcontroller from me.

I need to have a look but I am quite sure that I still have some left.
It would cost 10 Euro + postage.

Mail me privately if your interested and I will have a look if I can find
A chip.

Tip: If your existing microcontroller is socketed (normally they are) try
To remove it and put it in again - maybe the malfunction it is just because
of corrosion.

Ciao
Peter

http://www.ullrich.at.tt


-----Ursprüngliche Nachricht-----
Von: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] Im Auftrag von Karl Ekdahl
Gesendet: Freitag, 24. Oktober 2008 04:27
An: Bob Weigel; synth-diy at dropmix.xs4all.nl
Betreff: Re: [sdiy] Korg Polysix major problems - Update


Bob

> Well normally there will be a dead or multiple dead lines that should
> be chugging away with the clock generating data and addresses.

Oh no, i just verified that out of the eight lines going out of the processor (pin 34-27) only two are actually having any data on them, the others are totally stale.

> And then you
> have to establish if it's the cpu or something pulling a line down.

Hmm.. i didn't even realize these lines both go to the keyboard as well as to the KLM-371 - perhaps if i disconnect the cable to that board i'll at least see on which board the problem is.

> The code is inside of course so unless it's rapidly halting for some
> reason there should be stuff going on with all those lines.
>  I can't
> recall off the top how reset etc. are set up on that chip so consult
> diagram and besure those lines are doing what they should do also.
> Usually held low a reset is active to keep the chip out of the game.
> -Bob

Now i'm a little confused; are we talking hardware (memory) reset or a soft reset while power is on? I know there's a reset POT on the KLM-371 board but i don't really know what it's doing, guess i've gotta dig into the 8048/8049 datasheets...

As it does seem like i might need a new processor, did you say you had some? Would you be ok parting with one in that case and for how much?

Thanks

Karl

> Karl Ekdahl wrote:
>
> >So, it turns out that there is a good clock going to
> IC4 / IC5 that handles the gates, it's just not doing anything - the
> data coming in seems fine and the reset is constantly held HIGH as far
> as i can tell. I desoldered IC4 and tried triggering the gate on voice
> 4 manually and indeed it works just fine! The thing is though that it
> doesn't change frequency when i push any of the keys and the D/A i've
> verified to work so perhaps there's something else busted in the
> keyboard section?
> >
> >
> >
> >>I've had a cpu go bad on that board.
> That'd be
> >>first guess. You can of
> >>
> >>
> >
> >How do i verify if the CPU is dead?
> >
> >Thanks
> >
> >Karl
> >
> >
> >
> __________________________________________________________
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