Discussion about the Korg PolySix synthesizer

>Do you do repairs on Polysixes and if so where are you located? I've
>to a Polysix with what I think is factory installed midi and the
>output is weak and what I would call distorted. The patches change
>just fine and everything except for the sound seems to be fine.
>
>I'm not in a big hurry to fix it but would like to get it done at some point.
>
>cavernosum7 <<mailto:klosmon%40sbcglobal.net>klosmon@sbcglobal.net> wrote:
>Finally gotten around to securing programmable versions of the 8040 &
>8049 CPU chips used on the Polysix Processor and Voice boards; and
>after a long search, found an appropriate programmer.
>
>If anyone needs replacements for either of these, I can offer them for
>$30 each, plus shipping. These are new old stock 8748 & 8749 chips,
>programmed with the original Korg data and tested in my Polysix.
>
>HOWEVER, be aware that most of the repair problems you will encounter
>in a Polysix (mainly due to battery leakage) will not be solved by new
>CPU chips. These are not offered as a cure-all; just for people who
>KNOW that this is what they need.
>
>~GMM
>analogsynthservice.com
>
>---------------------------------
>Fussy? Opinionated? Impossible to please? Perfect. Join Yahoo!'s
>user panel and lay it on us.
>
>[Non-text portions of this message have been removed]
>
>

>I would also like to buy a replacement 1kx4 static ram (TC5514APL-3)

--- In PolySix@yahoogroups.com, "cavernosum7" <klosmon@...> wrote:
>
> Michael Grossman wrote:
> >Cavernosum, I bought a broken polysix which plays in tune and sounds
> >great except the programmer is flakey. Upon probing IC22-13 (DB1) I
> >noticed the pin has very low amplitude (<2V). I thought perhaps the
> RAM >chip might be bad so I pulled IC22-13 out of the socket and
> confirmed >the amplitude is still low. I am now convinced the
> uPD8048-245 is bad.
>
> Not necessarily. Have you checked IC31? On units with battery
> leakage, this is one of the most commonly damaged ICs. Try replacing
> that; if it still doesn't work, I'll sell you a new CPU.
>
> >I would also like to buy a replacement 1kx4 static ram (TC5514APL-3)
> if >available.
>
> Good news: you can use a 6514 RAM chip and it works exactly the same.
> These can be ordered from Jameco Electronics for about $4 each;
> Jameco part number 43238.
>
> ~GMM
>

--- In PolySix@yahoogroups.com, "mgrossm1" <mgrossm1@...> wrote:
>
> Cavernosum, yes I changed IC31 first before I got the scope out, made
> no difference. When I probed the CPU's data bus, I found DB1 had very
> low amplitude when compared to the other data bits.
>
> As a test, I slightly bent the CPU's data pins so when I plugged the
> CPU back in, they did not make contact with the socket. I probed each
> pin and confirmed DB1 still exhibited low amplitude while the other
> data bits besides DB1 were valid TTL levels.
>
> If a defect on the board other than the CPU was at fault my thinking
> is DB1 would also drive valid TTL levels hanging in free space.
>
> My understanding is the CPU has a multiplexed address/data bus so the
> data bus must first output the address until it is latched by the
> 14042s which actually drives the RAM address bus. Do you think this
> analysis is valid?
>
> I have sent my contact info to you in a separate email. Thanks for the
> help with the 6514 RAM chip.
>
> Mike
>
> --- In PolySix@yahoogroups.com, "cavernosum7" <klosmon@> wrote:
> >
> > Michael Grossman wrote:
> > >Cavernosum, I bought a broken polysix which plays in tune and sounds
> > >great except the programmer is flakey. Upon probing IC22-13 (DB1) I
> > >noticed the pin has very low amplitude (<2V). I thought perhaps the
> > RAM >chip might be bad so I pulled IC22-13 out of the socket and
> > confirmed >the amplitude is still low. I am now convinced the
> > uPD8048-245 is bad.
> >
> > Not necessarily. Have you checked IC31? On units with battery
> > leakage, this is one of the most commonly damaged ICs. Try replacing
> > that; if it still doesn't work, I'll sell you a new CPU.
> >
> > >I would also like to buy a replacement 1kx4 static ram (TC5514APL-3)
> > if >available.
> >
> > Good news: you can use a 6514 RAM chip and it works exactly the same.
> > These can be ordered from Jameco Electronics for about $4 each;
> > Jameco part number 43238.
> >
> > ~GMM
> >
>

> Greg, the CPU fixed my polysix. It was very nice of you to make these
> otherwise unobtainable CPUs available. BTW, thank you for sending the
> chip so fast. What a cool synth :)
>
> Best regards,
> Mike

--- In PolySix@yahoogroups.com, "cavernosum7" <klosmon@...> wrote:
>
> Michael Grossman wrote:
> >Cavernosum, I bought a broken polysix which plays in tune and sounds
> >great except the programmer is flakey. Upon probing IC22-13 (DB1) I
> >noticed the pin has very low amplitude (<2V). I thought perhaps the
> RAM >chip might be bad so I pulled IC22-13 out of the socket and
> confirmed >the amplitude is still low. I am now convinced the
> uPD8048-245 is bad.
>
> Not necessarily. Have you checked IC31? On units with battery
> leakage, this is one of the most commonly damaged ICs. Try replacing
> that; if it still doesn't work, I'll sell you a new CPU.
>
> >I would also like to buy a replacement 1kx4 static ram (TC5514APL-3)
> if >available.
>
> Good news: you can use a 6514 RAM chip and it works exactly the same.
> These can be ordered from Jameco Electronics for about $4 each;
> Jameco part number 43238.
>
> ~GMM
>