Synth-DIY Yahoo! Groups Archives

Thread

Osc 2 mod issues on just one voice

2013-02-25 by Eric Frampton

Hi folks -

So I'm finally making some progress getting this Polaris back up and on its feet. This one last issue has me stumped, tho'.

On one voice only (#2 of the 6), the mod routings accessed via the Assignable Control (Osc 2 Vibrato, Osc 2 Env, Detune) aren't working right. Pulling the control positive for Osc 2 Env creates this strange band-modulated sort of thing as the oscillator sweeps down, then pulling the slider negative, instead of creating a rising pitch like the other oscillators, starts with silence and fades in. Detune doesn't do anything at all, and Vibrato creates some sort of waveform that's different from the other 5 oscillators and just plain wrong. By itself - unmodulated - the oscillator runs and tracks just fine.

Again, this behavior is only on one voice - the other 5 are fine.

The oscillator seems to pass the Autotune routine - at least, the Tune light blinks 6 times.

Using a shotgun approach, I've tried individually swapping out the two 4051's on that voice, the LF347 for Pitch B, and the 3374 itself. No change for any of it.

Any thoughts?

Thanks,
Eric

Re: Osc 2 mod issues on just one voice

2013-02-25 by sukhoy27@...

--- In chromapolaris@yahoogroups.com, Eric Frampton <eric@...> wrote:

>
> Hi folks -
>
> So I'm finally making some progress getting this Polaris back up and on its feet. This one last issue has me stumped, tho'.
>
> On one voice only (#2 of the 6), the mod routings accessed via the Assignable Control (Osc 2 Vibrato, Osc 2 Env, Detune) aren't working right. Pulling the control positive for Osc 2 Env creates this strange band-modulated sort of thing as the oscillator sweeps down, then pulling the slider negative, instead of creating a rising pitch like the other oscillators, starts with silence and fades in. Detune doesn't do anything at all, and Vibrato creates some sort of waveform that's different from the other 5 oscillators and just plain wrong. By itself - unmodulated - the oscillator runs and tracks just fine.
>
> Again, this behavior is only on one voice - the other 5 are fine.
>
> The oscillator seems to pass the Autotune routine - at least, the Tune light blinks 6 times.
>
> Using a shotgun approach, I've tried individually swapping out the two 4051's on that voice, the LF347 for Pitch B, and the 3374 itself. No change for any of it.
>
> Any thoughts?
>
> Thanks,
> Eric
>

Hi , did you try to follow the test as indicated in the Service Manual , just like
Lower Function D , 4 and look if led over Master Volume slider
Turn on ?
I had many strange problem on my Polaris , like slider malfunction and test many IC's with scope and signal tracer, but simply replacing the ADC0804 all problems gone away !!!
Ciao
Mario

Re: [chromapolaris] Osc 2 mod issues on just one voice

2013-02-25 by Eric Frampton

Yep, I've done the whole service routine, and it all calibrated up just fine.

Unfortunately, I don't have any spare ADC0804's to toss in there. Where would I find one now?

On Feb 25, 2013, at 7:41 AM, sukhoy27@... wrote:

Hi , did you try to follow the test as indicated in the Service Manual , just like
Lower Function D , 4 and look if led over Master Volume slider
Turn on ?
I had many strange problem on my Polaris , like slider malfunction and test many IC's with scope and signal tracer, but simply replacing the ADC0804 all problems gone away !!!
Ciao
Mario

--- In chromapolaris@yahoogroups.com, Eric Frampton wrote:
>
> Hi folks -
>
> So I'm finally making some progress getting this Polaris back up and on its feet. This one last issue has me stumped, tho'.
>
> On one voice only (#2 of the 6), the mod routings accessed via the Assignable Control (Osc 2 Vibrato, Osc 2 Env, Detune) aren't working right. Pulling the control positive for Osc 2 Env creates this strange band-modulated sort of thing as the oscillator sweeps down, then pulling the slider negative, instead of creating a rising pitch like the other oscillators, starts with silence and fades in. Detune doesn't do anything at all, and Vibrato creates some sort of waveform that's different from the other 5 oscillators and just plain wrong. By itself - unmodulated - the oscillator runs and tracks just fine.
>
> Again, this behavior is only on one voice - the other 5 are fine.
>
> The oscillator seems to pass the Autotune routine - at least, the Tune light blinks 6 times.
>
> Using a shotgun approach, I've tried individually swapping out the two 4051's on that voice, the LF347 for Pitch B, and the 3374 itself. No change for any of it.
>
> Any thoughts?
>
> Thanks,
> Eric
>

RE: [chromapolaris] Osc 2 mod issues on just one voice

2013-02-25 by Paul D. DeRocco

> From: Eric Frampton
>
> Unfortunately, I don't have any spare ADC0804's to toss in
> there. Where would I find one now?

I wouldn't bother with an ADC0804. That won't fix something that only
affects one voice.

I suspect there's a hardware problem somewhere in the voice, which will take
proper diagnosis with a scope. You can't always fix things by blindly
swapping socketed ICs, although it's usually a good thing to try first.

--

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

Re: [chromapolaris] Osc 2 mod issues on just one voice

2013-02-25 by K S3

They have them here

http://www.futurlec.com/ICADC.shtml

From: Eric Frampton <eric@...>
To: chromapolaris@yahoogroups.com
Cc: sukhoy27@...
Sent: Monday, February 25, 2013 10:50 AM
Subject: Re: [chromapolaris] Osc 2 mod issues on just one voice

Yep, I've done the whole service routine, and it all calibrated up just fine.

Unfortunately, I don't have any spare ADC0804's to toss in there. Where would I find one now?

On Feb 25, 2013, at 7:41 AM, sukhoy27@... wrote:

Hi , did you try to follow the test as indicated in the Service Manual , just like
Lower Function D , 4 and look if led over Master Volume slider
Turn on ?
I had many strange problem on my Polaris , like slider malfunction and test many IC's with scope and signal tracer, but simply replacing the ADC0804 all problems gone away !!!
Ciao
Mario

--- In chromapolaris@yahoogroups.com, Eric Frampton wrote:
>
> Hi folks -
>
> So I'm finally making some progress getting this Polaris back up and on its feet. This one last issue has me stumped, tho'.
>
> On one voice only (#2 of the 6), the mod routings accessed via the Assignable Control (Osc 2 Vibrato, Osc 2 Env, Detune) aren't working right. Pulling the control positive for Osc 2 Env creates this strange band-modulated sort of thing as the oscillator sweeps down, then pulling the slider negative, instead of creating a rising pitch like the other oscillators, starts with silence and fades in. Detune doesn't do anything at all, and Vibrato creates some sort of waveform that's different from the other 5 oscillators and just plain wrong. By itself - unmodulated - the oscillator runs and tracks just fine.
>
> Again, this behavior is only on one voice - the other 5 are fine.
>
> The oscillator seems to pass the Autotune routine - at least, the Tune light blinks 6 times.
>
> Using a shotgun approach, I've tried individually swapping out the two 4051's on that voice, the LF347 for Pitch B, and the 3374 itself. No change for any of it.
>
> Any thoughts?
>
> Thanks,
> Eric
>

Re: Osc 2 mod issues on just one voice

2013-02-25 by sukhoy27@...

--- In chromapolaris@yahoogroups.com, Eric Frampton <eric@...> wrote:

>
> Yep, I've done the whole service routine, and it all calibrated up just fine.
>
> Unfortunately, I don't have any spare ADC0804's to toss in there. Where would I find one now?
>
> e
>
> On Feb 25, 2013, at 7:41 AM, sukhoy27@... wrote:
> > Hi , did you try to follow the test as indicated in the Service Manual , just like
> > Lower Function D , 4 and look if led over Master Volume slider
> > Turn on ?
> > I had many strange problem on my Polaris , like slider malfunction and test many IC's with scope and signal tracer, but simply replacing the ADC0804 all problems gone away !!!
> > Ciao
> > Mario
> >
> >
> > --- In chromapolaris@yahoogroups.com, Eric Frampton wrote:
> > >
> > > Hi folks -
> > >
> > > So I'm finally making some progress getting this Polaris back up and on its feet. This one last issue has me stumped, tho'.
> > >
> > > On one voice only (#2 of the 6), the mod routings accessed via the Assignable Control (Osc 2 Vibrato, Osc 2 Env, Detune) aren't working right. Pulling the control positive for Osc 2 Env creates this strange band-modulated sort of thing as the oscillator sweeps down, then pulling the slider negative, instead of creating a rising pitch like the other oscillators, starts with silence and fades in. Detune doesn't do anything at all, and Vibrato creates some sort of waveform that's different from the other 5 oscillators and just plain wrong. By itself - unmodulated - the oscillator runs and tracks just fine.
> > >
> > > Again, this behavior is only on one voice - the other 5 are fine.
> > >
> > > The oscillator seems to pass the Autotune routine - at least, the Tune light blinks 6 times.
> > >
> > > Using a shotgun approach, I've tried individually swapping out the two 4051's on that voice, the LF347 for Pitch B, and the 3374 itself. No change for any of it.
> > >
> > > Any thoughts?
> > >
> > > Thanks,
> > > Eric
> > >
> >
>

Hi Paul , I agree with You .
I do not know Eric did all service check !
I think that swapping out the two 4051's is a great idea.

Ciao

Mario

Re: Osc 2 mod issues on just one voice

2013-02-26 by Eric Frampton

It ended up being a couple of random things. Right out of the gate, ID10T fault: I was poking at the wrong voice channel.

When I started probing at the correct channel (d'oh!), everything up to the input of the 3374 was clean as it could be on the scope. So I tried re-seating the 3374, and voila, the output cleaned right up.

I then started exploring the filter section and discovered another voice not tracking the keyboard like the others. Re-seating to the rescue again, this time the 3372.

This is one of those units that was/is in such dodgy shape that, the more I dig into it, the more little things I find. It literally sat outside in a shed for years - I pulled leaves out of and cleaned rodent poo off of it. Wish I'd done before/after pix. If Paul hadn't come up with those new membrane panels (thanks again Paul!), I"m sure this thing would've just become parts for somebody.

Next up: Glide and Osc 2 Vibrato don't track slider moves like the rest of the parameters do. Details as I discover them...

On Feb 25, 2013, at 11:47 AM, Paul D. DeRocco <pderocco@...> wrote:

> From: Eric Frampton
>
> Unfortunately, I don't have any spare ADC0804's to toss in
> there. Where would I find one now?

I wouldn't bother with an ADC0804. That won't fix something that only
affects one voice.

I suspect there's a hardware problem somewhere in the voice, which will take
proper diagnosis with a scope. You can't always fix things by blindly
swapping socketed ICs, although it's usually a good thing to try first.

RE: [chromapolaris] Re: Osc 2 mod issues on just one voice

2013-02-26 by Paul D. DeRocco

> From: Eric Frampton
>
> Next up: Glide and Osc 2 Vibrato don't track slider moves
> like the rest of the parameters do. Details as I discover them...

As to glide, remember that glide only functions when you press the Sustain
footswitch. That also switches it to a monophonic mode, in which each note
reuses the last voice, instead of using an idle voice or the oldest used
voice.

Not sure what the Osc 2 Vibrato issue could be.

--

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

Re: [chromapolaris] Osc 2 mod issues on just one voice

2013-03-04 by Eric Frampton

Been looking into it, and still can't figure out what the Osc 2 Vibrato issue is. Rest of the unit is now working fine… I may just have to let that one go.

On Feb 26, 2013, at 11:11 AM, Paul D. DeRocco <pderocco@...> wrote:

> From: Eric Frampton
>
> Next up: Glide and Osc 2 Vibrato don't track slider moves
> like the rest of the parameters do. Details as I discover them...

As to glide, remember that glide only functions when you press the Sustain
footswitch. That also switches it to a monophonic mode, in which each note
reuses the last voice, instead of using an idle voice or the oldest used
voice.

Not sure what the Osc 2 Vibrato issue could be.

RE: [chromapolaris] Osc 2 mod issues on just one voice

2013-03-04 by Paul D. DeRocco

> From: Eric Frampton
>
> Been looking into it, and still can't figure out what the Osc
> 2 Vibrato issue is. Rest of the unit is now working fine. I
> may just have to let that one go.

Could you describe the symptom in a little more depth? What exactly happens?
You should ideally start with a scratch sound, to eliminate unnecessary
variables.

--

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

Re: [chromapolaris] Osc 2 mod issues on just one voice

2013-03-05 by Eric Frampton

As it turns out, what exactly happens is exactly what is supposed to happen - if there's no vibrato amount dialed in for oscillator 1, the bottom of the slider appears to be zero/dead for oscillator 2.

Now that this unit is completely working again (as I mentioned, there literally were dead leaves inside and rodent droppings all over the top from where it apparently lived in a barn for some years), I'm happy to say that I'm discovering all kinds of nice surprises. I'm carefully re-reading the owner's manual now to see what other goodies I've missed…

Thanks Paul!

Eric

On Mar 4, 2013, at 1:18 PM, Paul D. DeRocco <pderocco@...> wrote:

> From: Eric Frampton
>
> Been looking into it, and still can't figure out what the Osc
> 2 Vibrato issue is. Rest of the unit is now working fine. I
> may just have to let that one go.

Could you describe the symptom in a little more depth? What exactly happens?
You should ideally start with a scratch sound, to eliminate unnecessary
variables.