Vintage Synth Repair

>
> I'm currently restoring a Korg Trident Mk2. Not a lot of issues; a common leaking battery, a dead filter and a partially dead EG (release is always short) on synth board. Casing, contacts and pots cleaned, as well as the battery spillage, SSM2044 replaced (a SSM2056 is on the way from China), every thing else is fine. 
> 
> However, I was playing with it yesterday and I discovered a strange behavior; when key assignement put the synth on left of keyboard and the mode set to 1 (voices played on a round-robin mode), playing the B left of the split point 8 times (thus triggering all the 8 voices successively) yields a non-constant VCF cutoff; it can jump from fully open to fully closed. It is constant is the way if, say it is almost closed on the second played note, it also will be on the ninth, seventeenth, and so on. 
> 
> It happens on Synth section only, and once again, when I play other notes then this B, or if the Synth spans over the entire keyboard, it works ok.
> 
> Have you ever guys seen this?
> 
> Francois
>

>
> Sounds to me that the VCF cutoff just needs to be calibrated for all the 8 voices. There should be a trim pot for VCF cutoff for each voice on the voice board. Also those Chinese chips are probably fakes. If you want real, tested SSM2056s I have some.
> 
> Doug 
> synthparts.com
> 
> --- In vintagesynthrepair@yahoogroups.com, "alesisfusion8hd" <babouche369@> wrote:
> >
> > I'm currently restoring a Korg Trident Mk2. Not a lot of issues; a common leaking battery, a dead filter and a partially dead EG (release is always short) on synth board. Casing, contacts and pots cleaned, as well as the battery spillage, SSM2044 replaced (a SSM2056 is on the way from China), every thing else is fine. 
> > 
> > However, I was playing with it yesterday and I discovered a strange behavior; when key assignement put the synth on left of keyboard and the mode set to 1 (voices played on a round-robin mode), playing the B left of the split point 8 times (thus triggering all the 8 voices successively) yields a non-constant VCF cutoff; it can jump from fully open to fully closed. It is constant is the way if, say it is almost closed on the second played note, it also will be on the ninth, seventeenth, and so on. 
> > 
> > It happens on Synth section only, and once again, when I play other notes then this B, or if the Synth spans over the entire keyboard, it works ok.
> > 
> > Have you ever guys seen this?
> > 
> > Francois
> >
>

>
> Update: VCA EG (SSM2056) on voice 0 replaced. Everything now Ok, but definitely needs recalibration. Does anyone have the calibration procedure?
> 
> --- In vintagesynthrepair@yahoogroups.com, "synthparts" <synthparts@> wrote:
> >
> > Sounds to me that the VCF cutoff just needs to be calibrated for all the 8 voices. There should be a trim pot for VCF cutoff for each voice on the voice board. Also those Chinese chips are probably fakes. If you want real, tested SSM2056s I have some.
> > 
> > Doug 
> > synthparts.com
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "alesisfusion8hd" <babouche369@> wrote:
> > >
> > > I'm currently restoring a Korg Trident Mk2. Not a lot of issues; a common leaking battery, a dead filter and a partially dead EG (release is always short) on synth board. Casing, contacts and pots cleaned, as well as the battery spillage, SSM2044 replaced (a SSM2056 is on the way from China), every thing else is fine. 
> > > 
> > > However, I was playing with it yesterday and I discovered a strange behavior; when key assignement put the synth on left of keyboard and the mode set to 1 (voices played on a round-robin mode), playing the B left of the split point 8 times (thus triggering all the 8 voices successively) yields a non-constant VCF cutoff; it can jump from fully open to fully closed. It is constant is the way if, say it is almost closed on the second played note, it also will be on the ninth, seventeenth, and so on. 
> > > 
> > > It happens on Synth section only, and once again, when I play other notes then this B, or if the Synth spans over the entire keyboard, it works ok.
> > > 
> > > Have you ever guys seen this?
> > > 
> > > Francois
> > >
> >
>

>
> Should be in the service manual. Check the Polysix Yahoo group, I uploaded it to its Files section some time ago.
> 
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, "alesisfusion8hd" <babouche369@> wrote:
> >
> > Update: VCA EG (SSM2056) on voice 0 replaced. Everything now Ok, but definitely needs recalibration. Does anyone have the calibration procedure?
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "synthparts" <synthparts@> wrote:
> > >
> > > Sounds to me that the VCF cutoff just needs to be calibrated for all the 8 voices. There should be a trim pot for VCF cutoff for each voice on the voice board. Also those Chinese chips are probably fakes. If you want real, tested SSM2056s I have some.
> > > 
> > > Doug 
> > > synthparts.com
> > > 
> > > --- In vintagesynthrepair@yahoogroups.com, "alesisfusion8hd" <babouche369@> wrote:
> > > >
> > > > I'm currently restoring a Korg Trident Mk2. Not a lot of issues; a common leaking battery, a dead filter and a partially dead EG (release is always short) on synth board. Casing, contacts and pots cleaned, as well as the battery spillage, SSM2044 replaced (a SSM2056 is on the way from China), every thing else is fine. 
> > > > 
> > > > However, I was playing with it yesterday and I discovered a strange behavior; when key assignement put the synth on left of keyboard and the mode set to 1 (voices played on a round-robin mode), playing the B left of the split point 8 times (thus triggering all the 8 voices successively) yields a non-constant VCF cutoff; it can jump from fully open to fully closed. It is constant is the way if, say it is almost closed on the second played note, it also will be on the ninth, seventeenth, and so on. 
> > > > 
> > > > It happens on Synth section only, and once again, when I play other notes then this B, or if the Synth spans over the entire keyboard, it works ok.
> > > > 
> > > > Have you ever guys seen this?
> > > > 
> > > > Francois
> > > >
> > >
> >
>