Hi Don,
Thank you for your helpful response. Managed to get the VTL5C2 part ordered and will start the repairs on the polysix soon. It has a tuning problem and cannot be corrected anymore by calibrating. It also has had the LFO leaking into the VCO,s but that has already been fixed. Quite challenging figuring out how the schematics work without looking on the voiceboard, figured out that way that pin 3 has nc. Korg doesnt seem to have sharper pictures of the schematics. Will post the results back later here.. Cheers!
Simon
--- In PolySix@yahoogroups.com, "backshall1 \(dsl\)" <backshall1@...> wrote:
>
> Hi Simon,
> I haven't needed to replace another bad photocoupler so I haven't had a
> chance to try a VTL5C3. I also haven't noticed any problems with tuning with
> the VTL5C2 so I don't think there is a big enough difference to cause any
> trouble. It is important to note the wide variation of values used for R93,
> depending on which replacement you use for the P1501. It is always best to
> put in a 50K trimpot, set the tuning controls to mid-point, and set the
> trimpot for best initial tuning.
>
> As for "how" to do the replacement. I assume you are wondering how to put a
> 4-wire radial-lead component into a 6-pin DIP slot. Well, I guess it is
> really a 5-pin slot, since pin 5 doesn't exist. Going counter-clockwise,
> pins 1,2,3 go down the left side, and pins 4 and 6 go up the right side. Pin
> 5 is a blank space. Also, pin 3 is not connected to anything, so both old
> and new components are really 4-pin devices.
>
> On the P1501, the KLM-366 schematic shows that pins 1,2 are the anode and
> cathode of the LED, and pins 4,6 are the photo-resistor. You'll need the
> pin-out diagram for whatever part you are using as a replacement to see
> which two wires are the LED and which are the resistor, and what the
> polarity of the LED is. Once you are certain which wire goes where, heat up
> the soldering iron and get to work.
>
> Don B.
>
> _____
>
> From: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] On Behalf Of
> Andrew Jury
> Sent: Wednesday, May 11, 2011 5:09 AM
> To: PolySix@yahoogroups.com
> Subject: Re: [PolySix] Re: Replacement for HTV P1501 photocoupler?
>
>
>
>
> Hi,
>
> I¹ve always used the Siliconix NSL32 and a 39K resistor at position R93 and
> got very good results. Best of all they sell then off the shelf¹ at
> Farnell, which considerably saves time in sourcing them.
>
> Cheers,
> Andy
>
> On 10/05/2011 23:50, "ltern_te" <ninonine@...
> <mailto:ninonine%40xs4all.nl> > wrote:
>
> >
> >
> >
> >
> >
> > Hi Don/ Andy and thanks for your advice and feedback,
> >
> > Maybe a dummy question but how does one replace the P1501 with a VTL5CX ?
> Btw.
> > did anyone find out already if its better to use a VTL5C2 or VTL5C3
> > replacement?
> >
> > Thanks for the answer(s) in advance.
> >
> > Simon
> >
> > --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com>
> <mailto:PolySix%40yahoogroups.com> , Andrew
> > Jury <andy@> wrote:
> >> >
> >> > Thanks Don,
> >> >
> >> > You advice and expertise are much appreciated! I shall have a bit more
> of
> >> an
> >> > experiment, but I am at least ending up with the playable instrument
> for my
> >> > efforts rather than the sound of a piano that has been dropped out of a
> >> > window!
> >> >
> >> > Cheers,
> >> > Andy
> >> >
> >> >
> >> > On 27/07/2010 13:35, "longenough2002" <backshall1@> wrote:
> >> >
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >>> > > I tested this by setting VR1,2,3 to their midpoint, inserted a
> trimpot
> >>> for R93
> >>> > > and adjusted the pot for best scaling. It seemed to be about 40
> point
> >>> > > something K. 39K was the closest I had, so that's what I used. If
> you
> >>> have
> >>> > > more resistor choices (41K, 42K?) you might want to try one of those
> and
> see
> >>> > > if you get better results, or even leave in a 50K trimmer.
> >>> > > Don B.
> >>> > >
> >>> > > --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com>
> <mailto:PolySix%40yahoogroups.com>
> >>> <mailto:PolySix%40yahoogroups.com> , Andrew
> >>> > > Jury <andy@> wrote:
> >>>>> > >> >
> >>>>> > >> > Hi,
> >>>>> > >> >
> >>>>> > >> > Just wanted to say that I have been getting on very well with
> the
> >>>>> > >> > Silonex / 39k resistor mod. The only problem is the tuning is a
> bit
> >>>>> > >> > critical towards the lower end of the keyboard. Apart from that
> all
> is
> >>>>> > >> > well and I am on my fourth successful repair.
> >>>>> > >> >
> >>>>> > >> > Cheers,
> >>>>> > >> > Andy
> >>>>> > >> >
> >>>>> > >> >
> >>>>> > >> >
> >>>>> > >> > On 23 Jul 2010, at 16:31, "longenough2002" <backshall1@>
> >>>>> > >> > wrote:
> >>>>> > >> >
> >>>>>>>>> > >>>> > > > Shucks, just noticed a note in the "files" section
> from
> gil_we
> >>>>>>> > >>> > > back in Oct 2007 where he replaced the p1501 with a
> VTL5C3. I
> wonder
> >>>>>>> > >>> > > if the lower temperature coefficient of the VTL5C3 makes
> it a
> better
> >>>>>>> > >>> > > choice than the VTL5C2 for the tuning circuit? Some day, I
> gotta
> >>>>>>> > >>> > > read the rest of the stuff in there.
> >>>>>>> > >>> > > Don B.
> >>>>>>> > >>> > >
> >>>>>>> > >>> > > --- In PolySix@yahoogroups.com
> <mailto:PolySix%40yahoogroups.com>
> >>>>>>> <mailto:PolySix%40yahoogroups.com>
> <mailto:PolySix%40yahoogroups.com> ,
> M Ll
> >>>>> > >>> <f115@> wrote:
> >>>>>>>>> > >>>> > > >
> >>>>>>>>> > >>>> > > > Thanks for the update!
> >>>>>>> > >>> > >
> >>>>>>>>> > >>>> > > > ________________________________
> >>>>>>>>> > >>>> > > > From: longenough2002 <backshall1@>
> >>>>>>>>> > >>>> > > > To: PolySix@yahoogroups.com
> <mailto:PolySix%40yahoogroups.com>
> >>>>>>>>> <mailto:PolySix%40yahoogroups.com>
> <mailto:PolySix%40yahoogroups.com>
> >>>>>>>>> > >>>> > > > Sent: Sat, June 12, 2010 8:53:50 AM
> >>>>>>>>> > >>>> > > > Subject: [PolySix] Re: Replacement for HTV P1501
> >>>>>>>>> photocoupler?
> >>>>>>>>> > >>>> > > >
> >>>>>>>>> > >>>> > > >
> >>>>>>>>> > >>>> > > > Got another Polysix in the shop with tuning problems.
> Same sort of
> >>>>>>> > >>> > > thing with octaves "stretched" and it couldn't be
> corrected
> with the
> >>>>>>> > >>> > > trim pots. The diode side of the photocoupler tested bad,
> so
> it was
> >>>>>>> > >>> > > time to go shopping again. This time, I thought I would
> try
> one of
> >>>>>>> > >>> > > the Vactrol parts, so I got a Vactec VTL5C2 from Small
> Bear
> (same
> >>>>>>> > >>> > > place I got the Silonex part). I replaced R93 with 22K (up
> from
> >>>>>>> > >>> > > 4.7K) and it seems to be working very well, so now we have
> a
> couple
> >>>>>>> > >>> > > of choices for replacing the P1501.
> >>>>>>>>> > >>>> > > >
> >>>>>>>>> > >>>> > > > Don B.
> >>>>>>>>> > >>>> > > >
> >>>>>>>>> > >>>> > > >
> >>>>>>> > >>> > >
> >>>>>>> > >>> > >
> >>>>> > >> >
> >>>>> > >> >
> >>>>> > >> > [Non-text portions of this message have been removed]
> >>>>> > >> >
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >> >
> >> >
> >> >
> >> > [Non-text portions of this message have been removed]
> >> >
> >
> >
> >
> >
> >
>
> [Non-text portions of this message have been removed]
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>