[sdiy] Korg Polysix major problems - Update

[Karl Ekdahl]

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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