Rhodes Chroma Polaris

For some reason the other voices sound fine. 3 was the worst. After cleaning things up a bit..now 2 is what three was. Oh and I swapped out the fast 4051 analog switch and op amp that drives the vca in. I was seeing a sawtooth there... leaky S+H I was thinking?

Also 5 doesn't tune yet I can turn it back on and it sounds ok. it's envelope is strange though. Sustains with that level at zero then turns off w/out it moving. That makes no sense. hmmm. rechecking that..anyway if anyone has seen anything similar... I saw something kinda similar on a siel dk600 where it was that voltages were peaking on the DAC out higher than the reference voltage on 4051's. I adjusted the dac though and...why would it be doing it on three and not the last three?

> From: Robert Weigel
>
> For some reason the other voices sound fine. 3 was the
> worst. After cleaning things up a bit..now 2 is what three
> was. Oh and I swapped out the fast 4051 analog switch and op
> amp that drives the vca in. I was seeing a sawtooth there...
> leaky S+H I was thinking?

Yup, that's what leakage looks like.

> Also 5 doesn't tune yet I can turn it back on and it sounds
> ok. it's envelope is strange though. Sustains with that
> level at zero then turns off w/out it moving. That makes no
> sense. hmmm. rechecking that..anyway if anyone has seen
> anything similar... I saw something kinda similar on a siel
> dk600 where it was that voltages were peaking on the DAC out
> higher than the reference voltage on 4051's. I adjusted the
> dac though and...why would it be doing it on three and not
> the last three?

Not sure what you mean by "Sustains with that level at zero then turns off
w/out it moving." However, I do recall that the volume envelope has a
squelch so that when it gets to zero, it is suddenly driven negative, to
kill any possible bleedthrough. When you do the Volume Offset adjustment
(LF, A, 9), this squelching is suppressed so that you can hear if there's
any residual offset. Unless you mean something completely different, I think
you need to do the Volume Offset adjustment.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

Yeah Paul it doesn't seem to do that... if you turn the voice off it goes to negative volts again. But as soon as you hit a note the volume goes to zero and sets there indefinitely I think... weird..

Anyway hopefully can figure the source of it here. The 4051's made no difference. Those caps never leak I'm sure and to have 3 paralell channels? Odd. Maybe I should just hose the whole board with chemtronics..might be a residue issue around the S_H 's

--- In chromapolaris@yahoogroups.com, "Paul D. DeRocco" <pderocco@...> wrote:
>
> > From: Robert Weigel
> >
> > For some reason the other voices sound fine. 3 was the
> > worst. After cleaning things up a bit..now 2 is what three
> > was. Oh and I swapped out the fast 4051 analog switch and op
> > amp that drives the vca in. I was seeing a sawtooth there...
> > leaky S+H I was thinking?
>
> Yup, that's what leakage looks like.
>
> > Also 5 doesn't tune yet I can turn it back on and it sounds
> > ok. it's envelope is strange though. Sustains with that
> > level at zero then turns off w/out it moving. That makes no
> > sense. hmmm. rechecking that..anyway if anyone has seen
> > anything similar... I saw something kinda similar on a siel
> > dk600 where it was that voltages were peaking on the DAC out
> > higher than the reference voltage on 4051's. I adjusted the
> > dac though and...why would it be doing it on three and not
> > the last three?
>
> Not sure what you mean by "Sustains with that level at zero then turns off
> w/out it moving." However, I do recall that the volume envelope has a
> squelch so that when it gets to zero, it is suddenly driven negative, to
> kill any possible bleedthrough. When you do the Volume Offset adjustment
> (LF, A, 9), this squelching is suppressed so that you can hear if there's
> any residual offset. Unless you mean something completely different, I think
> you need to do the Volume Offset adjustment.
>
> --
>
> Ciao, Paul D. DeRocco
> Paul mailto:pderocco@...
>

> From: synthwookie
>
> Yeah Paul it doesn't seem to do that... if you turn the voice
> off it goes to negative volts again. But as soon as you hit
> a note the volume goes to zero and sets there indefinitely I
> think... weird..

Well, now I'm confused. Your last post said, "Sustains with that level at
zero then turns off w/out it moving." Could you rephrase that? Are you
playing a scratch sound, or something with a non-infinite decay time on the
volume envelope, or something with some nonzero release time on the volume
envelope? What is the voltage doing, and what is the sound doing?

> Anyway hopefully can figure the source of it here. The
> 4051's made no difference. Those caps never leak I'm sure
> and to have 3 paralell channels? Odd. Maybe I should just
> hose the whole board with chemtronics..might be a residue
> issue around the S_H 's

Well, Clean is Good, but so far I don't think you've got a S&H problem.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

Sorry yeah I was just adding some vca release time to a scratch sound.

--- In chromapolaris@yahoogroups.com, "Paul D. DeRocco" <pderocco@...> wrote:
>
> > From: synthwookie
> >
> > Yeah Paul it doesn't seem to do that... if you turn the voice
> > off it goes to negative volts again. But as soon as you hit
> > a note the volume goes to zero and sets there indefinitely I
> > think... weird..
>
> Well, now I'm confused. Your last post said, "Sustains with that level at
> zero then turns off w/out it moving." Could you rephrase that? Are you
> playing a scratch sound, or something with a non-infinite decay time on the
> volume envelope, or something with some nonzero release time on the volume
> envelope? What is the voltage doing, and what is the sound doing?
>
> > Anyway hopefully can figure the source of it here. The
> > 4051's made no difference. Those caps never leak I'm sure
> > and to have 3 paralell channels? Odd. Maybe I should just
> > hose the whole board with chemtronics..might be a residue
> > issue around the S_H 's
>
> Well, Clean is Good, but so far I don't think you've got a S&H problem.
>
> --
>
> Ciao, Paul D. DeRocco
> Paul mailto:pderocco@...
>

ahh it seems i finally got a stress correlation on a socket and worked that stuff over and it seems we've got reasonably close noise baselines except..on 5 where it's much quieter.... but it still does that thing where if you turn it ON...then it changes voltage there on the first hit then stays at zero roughly and never changes again! yet..the note..plays. I don't get it.

Anyway if I can figure why 5 isn't on after tuning I think we'll have it. I changed the CEM chips...no result. The op amp that does the vca...nothing..the 4051's...nope. If I turn 5 on it always sounds in reasonable tune. What in the world!? What *ELSE* does it check for before it turns the channel on?

--- In chromapolaris@yahoogroups.com, "Robert Weigel" <sounddoctorin@...> wrote:
>
>
> Sorry yeah I was just adding some vca release time to a scratch sound.
>
>
> --- In chromapolaris@yahoogroups.com, "Paul D. DeRocco" <pderocco@> wrote:
> >
> > > From: synthwookie
> > >
> > > Yeah Paul it doesn't seem to do that... if you turn the voice
> > > off it goes to negative volts again. But as soon as you hit
> > > a note the volume goes to zero and sets there indefinitely I
> > > think... weird..
> >
> > Well, now I'm confused. Your last post said, "Sustains with that level at
> > zero then turns off w/out it moving." Could you rephrase that? Are you
> > playing a scratch sound, or something with a non-infinite decay time on the
> > volume envelope, or something with some nonzero release time on the volume
> > envelope? What is the voltage doing, and what is the sound doing?
> >
> > > Anyway hopefully can figure the source of it here. The
> > > 4051's made no difference. Those caps never leak I'm sure
> > > and to have 3 paralell channels? Odd. Maybe I should just
> > > hose the whole board with chemtronics..might be a residue
> > > issue around the S_H 's
> >
> > Well, Clean is Good, but so far I don't think you've got a S&H problem.
> >
> > --
> >
> > Ciao, Paul D. DeRocco
> > Paul mailto:pderocco@
> >
>

Paul, the reason 5 isn't tuning is still a mystery. I swapped all the chips. No result. However the reading I was getting... that was on the wrong resistor. They changed the pattern I see. The envelope is showing up if I get it on the right resistor :-). It looked like a clear pattern but for some reason on 5 they changed it! I couldn't see the writing... anyway I figured probably the hard wired leg 4053 chip but no dice. Still doesn't tune until I turn it on..then..I find out ..it's tuned. Whaaaaatever. I dunno. I need to see the code i guess to know what routine it goes through on the tuning. lol

--- In chromapolaris@yahoogroups.com, "Robert Weigel" <sounddoctorin@...> wrote:

>
> Paul, the reason 5 isn't tuning is still a mystery. I swapped all the chips. No result. However the reading I was getting... that was on the wrong resistor. They changed the pattern I see. The envelope is showing up if I get it on the right resistor :-). It looked like a clear pattern but for some reason on 5 they changed it! I couldn't see the writing... anyway I figured probably the hard wired leg 4053 chip but no dice. Still doesn't tune until I turn it on..then..I find out ..it's tuned. Whaaaaatever. I dunno. I need to see the code i guess to know what routine it goes through on the tuning. lol
>

PS I checked the tune buffer in also and it looks about the same on all channels. Actually 5's signal looks just a hair hotter for some reason. 5% maybe. 4's is weakest I think and it works fine. Maybe I should..attenuate it some? Too weird. 5's light is always off after I tune when I do lower function E....

> From: Robert Weigel
>
> Paul, the reason 5 isn't tuning is still a mystery. I
> swapped all the chips. No result. However the reading I was
> getting... that was on the wrong resistor. They changed the
> pattern I see. The envelope is showing up if I get it on the
> right resistor :-). It looked like a clear pattern but for
> some reason on 5 they changed it! I couldn't see the
> writing... anyway I figured probably the hard wired leg 4053
> chip but no dice. Still doesn't tune until I turn it
> on..then..I find out ..it's tuned. Whaaaaatever. I dunno.
> I need to see the code i guess to know what routine it goes
> through on the tuning. lol

The order in which things are tuned is channel 1 through channel 6. Within
each channel, it tunes pitch 1, pitch 2, width 1, width 2 and cutoff. The
Tune switch LED is on while tuning the pitches. You can usually tell where
the process failed by forcibly enabling that channel and disabling the
others, and then seeing whether the oscillators are in tune, and whether the
pulse width goes from 0% to 99% with a proper square wave at 50%.

> PS I checked the tune buffer in also and it looks about the
> same on all channels. Actually 5's signal looks just a hair
> hotter for some reason. 5% maybe. 4's is weakest I think
> and it works fine. Maybe I should..attenuate it some? Too
> weird. 5's light is always off after I tune when I do lower
> function E....

Don't bother. There's nothing wrong with the signal being a little hotter.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

I wouldn't have thought so Paul. Here's what happened when I started swapping vcf/vca chips to try to even the levels out just for the fun of it...

>

Well.... this is bizarre. I recall someone saying prophet 600 filter/vca chips could be very picky too...(maybe that's the issue I have with a P600 here that has to warm up a bit to tune?) But didn't recall the Polaris was picky. So I noticed there was some level discrepancy in the auto tune. yet waveforms coming in to the CEM3372 looked fairly identical. Most are near the same but ch4 is actually lower by 5% maybe and 5 the one that won't tune higher by about the same.

I swap the chips. Four AND Five fail now consistently! (And yes the levels have swapped. Now 4 is high and 5 is low so it is being caused by vca discrepancies apparently) . Now I swap in a pair of chips from a scrap polaris with the same lot number. ch4 is back up..still no channel 5. And I look on the scope and I see that 4 is actually right in there now but 5 is back up high again.

So I finally swap 4 and 5 again and this time they all work! Wow. So I guess there are some fairly fine tolerences there for whatever reason. I thought we're like..just dealing with a comparator in the tune buffer that chops the signals like usual and gives a nice square wave that can be counted. Anybody got an explanation?

-------continuing

So that's the story on this end. Paul I am the king of bizarre problems. lol. It makes absolutely no sense to me.

--- In chromapolaris@yahoogroups.com, "Paul D. DeRocco" <pderocco@...> wrote:
>
> > From: Robert Weigel
> >
> > Paul, the reason 5 isn't tuning is still a mystery. I
> > swapped all the chips. No result. However the reading I was
> > getting... that was on the wrong resistor. They changed the
> > pattern I see. The envelope is showing up if I get it on the
> > right resistor :-). It looked like a clear pattern but for
> > some reason on 5 they changed it! I couldn't see the
> > writing... anyway I figured probably the hard wired leg 4053
> > chip but no dice. Still doesn't tune until I turn it
> > on..then..I find out ..it's tuned. Whaaaaatever. I dunno.
> > I need to see the code i guess to know what routine it goes
> > through on the tuning. lol
>
> The order in which things are tuned is channel 1 through channel 6. Within
> each channel, it tunes pitch 1, pitch 2, width 1, width 2 and cutoff. The
> Tune switch LED is on while tuning the pitches. You can usually tell where
> the process failed by forcibly enabling that channel and disabling the
> others, and then seeing whether the oscillators are in tune, and whether the
> pulse width goes from 0% to 99% with a proper square wave at 50%.
>
> > PS I checked the tune buffer in also and it looks about the
> > same on all channels. Actually 5's signal looks just a hair
> > hotter for some reason. 5% maybe. 4's is weakest I think
> > and it works fine. Maybe I should..attenuate it some? Too
> > weird. 5's light is always off after I tune when I do lower
> > function E....
>
> Don't bother. There's nothing wrong with the signal being a little hotter.
>
> --
>
> Ciao, Paul D. DeRocco
> Paul mailto:pderocco@...
>