Discussion about the Korg PolySix synthesizer

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,

I�ve 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 shelf� at
Farnell, which considerably saves time in sourcing them.

Cheers,
Andy

On 10/05/2011 23:50, "ltern_te" <ninonine@xs4all.nl
<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]
>> >
>
>
>
>
>

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