Hi Don,
I've finally found the time and finished repairing. I needed to put abt 9 k on the trimpot placed on the R93 location for a good stability in tuning for the Polysix again. All in tune now between lower and upper C's. I used the VTL5C2 replacement. Thank you and all for contributing to this subject, this was a great help. 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]
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