Discussion about the Korg PolySix synthesizer

There shouldn't be any connectivity -- either there's a short you 
haven't found yet, or there's a problem with IC 31.
I've about reached the limit of my long-distance diagnostic ability....


~G
choco wrote:
>
> Hi!
>
> After cutting almost every trace on the D00 bus i realised that that
> wasn't the matter of that short I discovered before.
>
> In fact I'm not sure about what's happening, but I will try to explain
> it, maybe you will find it normal.
>
> Does it make any sense to you? (with the battery placed in the holder)
> There is connectivity between the positive side of the battery and the
> output of an AND gate on IC31 (Pin 6),(giving a value as if it were an
> inverse diode or something like that) when plugging the negative probe
> on the battery side, but it gives no connectivity when changing the
> probes??
>
> When removing the battery no connectivity issues are shown beetween them.
>
> It seems something normal related to the values that the latch
> delivers when the battery is in place, but I have not the tools to
> measure this kind of logical issues and also I am not skilled to do it.
>
> Any Idea that could affect to the effect speed?
>
> Thank you one more time... now it's time to rewire D00 :(
>
> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com>, 
> klosmon <klosmon@...> wrote:
> >
> > Sounds like D00 is shorted; start by cutting the traces to that line
> > around IC31 -- if the short goes away, you know where to look. If not,
> > cut the D00 trace to each of the other ICs & connectors, one at a time,
> > checking the status of the short as you go.
> >
> > ~G
> > choco wrote:
> > >
> > > Hi.
> > >
> > > I've checked tha traces and seemed to be ok, but accidentaly I found
> > > something that I didn't understand.
> > >
> > > The D00 (CN06-3) seems to be connected to the +3.6 pin of the battery
> > > (and to the new diode which replaced the resistor there), and also to
> > > the D15 anode (which is really close to that trace). I removed the new
> > > diode and soldered it to the battery old soldering point which was not
> > > used and goes through the other side of the board. I cut the trace
> > > which connected the battery to the old resistor just for checking, but
> > > the connection was still there.
> > >
> > > Does it make any sense to you? The tracks and the board seem to be in
> > > good condition and the battery didn't almost leak when I replaced it,
> > > but it sounds to me that the board could be conductive or something
> > > like that.
> > >
> > > I just wanted to ask you before cutting all the traces on the board...
> > >
> > > Maybe tomorrow I will try to remove all the D00 traces and make cable
> > > connections.
> > >
> > > Thank you!
> > >
> > > --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> 
> <mailto:PolySix%40yahoogroups.com>,
> > > klosmon <klosmon@> wrote:
> > > >
> > > > Most likely cause is another bad trace.
> > > > Check all the traces to CN06 (D00 - D03; P10 - P13).
> > > > Also keep in mind that these signals each have to connect to several
> > > > points on the board (for example, D00 connects to IC31-6, IC26-4,
> > > > CN06-3, IC28-4, IC34-4, etc etc).
> > > >
> > > > ~G
> > > >
> > > > choco wrote:
> > > > >
> > > > > Hi!
> > > > >
> > > > > Finnaly I managed to repair it! It was just a track that I cut
> > > > > accedentally and was under a printed number on the board (it was
> > > > > almost impossible to see it)
> > > > >
> > > > > Now I've got another problem. The synth sounds ok, it stores the
> > > > > presets and so on, but it seems to be a problem with the
> modulation
> > > > > section that it doesn't had before I managed to change the
> battery.
> > > > >
> > > > > What happens is: when i switch the P6 on the LFO led starts
> flashing
> > > > > faster and faster and every change of the pots doesn't affect
> to it.
> > > > > Did you encounter this problem before? I've tried to do the
> Modulation
> > > > > adjustment but the VR changes doesn't seem to affect to the signal
> > > > > that is delivered to CN03-5. Well, I'm doing it with a digital
> > > > > voltimeter which stands to measure Hz, but maybe that's not a good
> > > way...
> > > > >
> > > > > any idea?
> > > > >
> > > > > Thank you in advance.
> > > > >
> > > > > --- In PolySix@yahoogroups.com 
> <mailto:PolySix%40yahoogroups.com> <mailto:PolySix%40yahoogroups.com>
> > > <mailto:PolySix%40yahoogroups.com>,
> > > > > "choco" <ignaciojimenez@> wrote:
> > > > > >
> > > > > > Hi-
> > > > > >
> > > > > > Thank you for your fast and kind reply.
> > > > > >
> > > > > > I have visited your website several times when doing
> research for my
> > > > > > P6 and I had you in mind as an option if I couldn't work it
> out. My
> > > > > > synth comes from the states and I was bothered about sending it
> > > back,
> > > > > > but I've never thought before about sending just the board.
> It's a
> > > > > > great option.
> > > > > >
> > > > > > I'll check one more time that traces and maybe I will
> re-solder them
> > > > > > and the socket more accurately just for testing.
> > > > > >
> > > > > > Probably I will contact you in a week if I can't arrange to
> > > repair it.
> > > > > >
> > > > > > And maybe I'll think about getting a scope.
> > > > > >
> > > > > > Thank you!
> > > > > >
> > > > > > --- In PolySix@yahoogroups.com 
> <mailto:PolySix%40yahoogroups.com>
> > > <mailto:PolySix%40yahoogroups.com> <mailto:PolySix%40yahoogroups.com>,
> > > > > klosmon <klosmon@> wrote:
> > > > > > >
> > > > > > > Hello-
> > > > > > > Having repaired many of these, I would suggest that the most
> > > likely
> > > > > > > cause is damaged traces due to the battery leak.
> > > > > > > Even if the board looks good, the traces around IC31
> (which you
> > > > > > > replaced) are VERY delicate, and carry data lines that, if
> > > damaged,
> > > > > > > effect all of the functions of the synth.
> > > > > > >
> > > > > > > If you have any experience with electronics, get hold of the
> > > > > schematic
> > > > > > > and use a continuity tester to test all traces from that IC;
> > > if you
> > > > > > > have a scope, that's even faster.
> > > > > > >
> > > > > > > If not, you can send me the CPU board & I can look it over for
> > > you.
> > > > > > >
> > > > > > > ~GMM
> > > > > > > analogsynthervice.com
> > > > > > >
> > > > > > >
> > > > > > > choco wrote:
> > > > > > > >
> > > > > > > > Hi!
> > > > > > > >
> > > > > > > > After digging within the messages I haven't found any
> similar
> > > > > > > > situation, so I decided to post.
> > > > > > > >
> > > > > > > > I bought a year ago and old polysix and it sounded fine to
> > > me (maybe
> > > > > > > > lower than expected, I use it with an old guitar tube amp
> > > and I have
> > > > > > > > to select the high output with master at 12 o'clock to
> get it at
> > > > > > > > almost the same level as the guitar is)
> > > > > > > >
> > > > > > > > A mounth ago I noticed that I had lost all my patches
> (although
> > > > > it was
> > > > > > > > sounding great and every pot worked fine). I did know
> about the
> > > > > > > > battery issues, but it hadn't worried me until that moment.
> > > I opened
> > > > > > > > the polysix and noticed that the battery mounting clamps
> > > were broken
> > > > > > > > and the batery was not feeding the klm367A anymore.
> > > > > > > >
> > > > > > > > Well, it had leaked a little bit, but the circuit was almost
> > > perfect
> > > > > > > > and there were no signs of corrosion elsewhere. I cleaned
> > > all the
> > > > > > > > board with alcohol and care, replaced the battery and the
> > > 74LS08N
> > > > > > > > which is next to it just for security and then I made a
> mistake.
> > > > > > > >
> > > > > > > > I broke a trace and shorted accidentaly 5V and ground.
> > > > > > > >
> > > > > > > > After testing and noticing what the matter was, I
> removed that
> > > > > mistake
> > > > > > > > and everything seemed to work fine (the leds and so on), but
> > > when I
> > > > > > > > pluged the P6 to an amp (to the earphones too), I noticed
> > > that it
> > > > > > > > sounded weak and something like distorted. almost every pot
> > > didn't
> > > > > > > > affect as expected.
> > > > > > > >
> > > > > > > > Do you have any idea of what can happen to my beloved P6?Any
> > > measure
> > > > > > > > that I could take from it to get deeper into? Unfortunately
> > > I don't
> > > > > > > > have an osciloscope to take accurate measures...
> > > > > > > >
> > > > > > > > I also had a problem with 15Volt line, all the LEDs were
> ON when
> > > > > > > > starting up the P6, but never went OFF. In addition to
> it, the
> > > > > > > > Modulation LFO LED started blinking every time faster
> and faster
> > > > > until
> > > > > > > > it seemed to be just static ON. I solved it regulating
> the 15V
> > > > > pot to
> > > > > > > > get over 15.05 on my meter.
> > > > > > > >
> > > > > > > > I will continue testing it, but it seems that I have reached
> > > my best
> > > > > > > > effort in front of it, and here in Spain it's almost
> impossible
> > > > > > > > finding a qualified vintage synth tech.
> > > > > > > >
> > > > > > > > Thank you in advance.
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
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> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > >
> > >
> >
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> >
>
>  



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