[sdiy] Korg Polysix major problems - Update

[Bob Weigel]

Hmm...yeah that doesnt' sound real likely.  Like I say I had an 8049 go 
down recently while troubleshooting the other board which was bizarre.  
Swapped in the chip from a spare board and voila.  But I'd have to 
review diagram for that section to think of some good procedures and I'm 
a bit busy for a few days here.  Maybe somebody else has a thought off 
the top on that.  Trying to recall how the reset line is on that cpu 
etc. -Bob

Karl Ekdahl wrote:

>Guys
>
>One last question before i give up on this CPU; how common is the problem of the CPU dying and *which* CPU are we talking about, the 8048 or the 8049 (i believe the latter might be my problem). The reason i'm asking is because i in fact have two sets of boards for the polysix and each board behaves the same which i thought was kinda weird. I have of course tried swapping the CPUs inbetween the boards as well as hooking up all of the boards with eachother in different configurations.
>
>Karl
>
>
>--- Den fre 2008-10-24 skrev Ullrich Peter <Peter.Ullrich at kapsch.net>:
>
>  
>
>>Från: Ullrich Peter <Peter.Ullrich at kapsch.net>
>>Ämne: Re: [sdiy] Korg Polysix major problems - Update
>>Till: "elektrodwarf at yahoo.se" <elektrodwarf at yahoo.se>, "Bob Weigel" <sounddoctorin at imt.net>, "synth-diy at dropmix.xs4all.nl" <synth-diy at dropmix.xs4all.nl>
>>Datum: fredag 24 oktober 2008 08.26
>>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
>>>>
>>>>
>>>>
>>>>        
>>>>
>>__________________________________________________________
>>    
>>
>>>>Låna pengar utan säkerhet. Jämför vilkor
>>>>        
>>>>
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>>    
>>
>>>Kelkoo.
>>>
>>>http://www.kelkoo.se/c-100390123-lan-utan-sakerhet.html?partnerId=969
>>>      
>>>
>>>>15014
>>>>
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>>>>
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>>>>
>>     
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