100KB sliders

[rabiticide]

First of all, I assume that "MA" is Korg-speak for "Megohm".
(Normally just abbreviated "M".) Whatever, if your replacement pots
are half the value of the originals, all the time constants will be
halved as well (envelopes speeded up x2) for the same relative
settings. If you rarely use the half of the sliders that give the
longest envelopes, you might be happy with a simple replacement.
However, if you want to restore the original range, you can also
replace capacitor C6 with one of twice its value. Note that this is
an electrolytic, so be sure to observe polarities.

Best regards,

Bob Masta

okay, last question (I hope!). Can I do 100KA for the pot (1/20th the
value) and replace the cap with 200uF (20 X the value) for an
equivalent circuit? I was mistaken about the 1 MA, it's only
available if I order 200 at $2 a piece!

Yes, the "A" stands for audio taper.
Yes, the coating is worn off so no amount of cleaning will help

rK

 

[Allen Bong]

On Apr 1, 3:34 am, rabiticide <rabitic...@gmail.com> wrote:

First of all, I assume that "MA" is Korg-speak for "Megohm".
(Normally just abbreviated "M".)  Whatever, if your replacement pots
are half the value of the originals, all the time constants will be
halved as well (envelopes speeded up x2) for the same relative
settings.  If you rarely use the half of the sliders that give the
longest envelopes, you might be happy with a simple replacement.
However, if you want to restore the original range, you can also
replace capacitor C6 with one of twice its value.  Note that this is
an electrolytic, so be sure to observe polarities.

Best regards,

Bob Masta

okay, last question (I hope!).  Can I do 100KA for the pot (1/20th the
value) and replace the cap with 200uF (20 X the value) for an
equivalent circuit?  I was mistaken about the 1 MA, it's only
available if I order 200 at $2 a piece!

Yes, the "A" stands for audio taper.
Yes, the coating is worn off so no amount of cleaning will help

rK

Hi Ribiticide,

Take a look at the pots and sliders that I have. Do they match the
sliders of yours that went bad?
I am a part time Yamaha and Kawai organ technician and I can get the
old parts if I try.

http://www.flickr.com/photos/11236051@N08/sets/72157601399254969/


Allen

 

[Bob Masta]

On Mon, 31 Mar 2008 12:34:03 -0700 (PDT), rabiticide
<rabiticide@gmail.com> wrote:

First of all, I assume that "MA" is Korg-speak for "Megohm".
(Normally just abbreviated "M".) Whatever, if your replacement pots
are half the value of the originals, all the time constants will be
halved as well (envelopes speeded up x2) for the same relative
settings. If you rarely use the half of the sliders that give the
longest envelopes, you might be happy with a simple replacement.
However, if you want to restore the original range, you can also
replace capacitor C6 with one of twice its value. Note that this is
an electrolytic, so be sure to observe polarities.

Best regards,

Bob Masta


okay, last question (I hope!). Can I do 100KA for the pot (1/20th the
value) and replace the cap with 200uF (20 X the value) for an
equivalent circuit? I was mistaken about the 1 MA, it's only
available if I order 200 at $2 a piece!

Yes, the "A" stands for audio taper.
Yes, the coating is worn off so no amount of cleaning will help

Looks like 100KA and 200uF should work just fine.

Best regards,


Bob Masta

DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!

 

[Rich Grise]

On Tue, 25 Mar 2008 11:53:30 -0700, rabiticide wrote:

On Mar 23, 6:00 am, BobG <bobgard...@aol.com> wrote:
Just post a link to a photo of the sliders against some size
reference... there's a bunch of misc sliders at Skycraft... did we
determine if they were linear or audio?

It's linear. But now I have another problem: The attack slider works
but is a little scratchy, so I'd like to replace it now that I've got
it pulled off the board. It is designated as "2MA" Nothing I can find
has such high resistance. I don't know why they would design it this
way.

Sorry, but is is not very helpful. Is it possible at all for you to post
a picture somewhere? Either on your ISP's "personal webspace" (every ISP
I've had has provide a personal page of maybe 10 MB.) or one of those
free photo hosts.

And also, for some reason I don't trust those numbers - they could be
house numbers and I don't know if _anybody_ has ever heard of a 2M
slider. Would you ohm them out? Or are they blown already? Is the
company still in business? Could you ask them for a parts list, or
even order replacements? Is there a Sams PhotoFact for it?

BTW, It's a lesson I learned that the resistance of a component is
best measured when disconnected from the circuit. Is this correct?

Yes; there are always sneak paths somewhere when it's in-circuit. Of
course, you know to NEVER EVER use an ohmmeter on an energized circuit.
Voltmeters are fine, of course - that's how we troubleshoot stuff.

Cheers!
Rich

 

[Rich Grise]

On Sun, 30 Mar 2008 11:50:13 -0700, BobG wrote:

I've tried lots of Home Remedies to cure scratchy tube guitar amp
pots.. I've heard WD40.... others say nooooo... thats a solvent and
will eat the conductive plastic... How about Amway or some similar
silicon slippery stuff (wow 5 Ss in a row)? Just need to knock the
dust off the wiper area.

The problem with WD-40 is that it gums up whatever it touches. If
you think you've got a scratchy pot, a little WD-40 will not only
silence the scratchiness, but the whole shebang - it will coat the
element, and the slider won't make contact again until you use proper
control cleaner stuff. And, of course, when you spray the control
cleaner on the part, be sure and work the wiper back and forth to,
well, wipe it.

I once got an old teletype unit donated to me because the guy was
tired of hauling it around with him. It was very dusty, so I figured
I'd clean it, so I sprayed it with WD-40. It gummed up the unit so
bad it wouldn't even operate. I spent about a week dismantling the
thing and cleaning the individual parts in isopropyl alcohol, with
a typewriter brush.

WD-40 is for squeaky car front ends, door hinges, and keeping your
garden tools from rusting. ;-)

Cheers!
Rich

 

[rabiticide]

Hi Ribiticide,

Take a look at the pots and sliders that I have. Do they match the
sliders of yours that went bad?
I am a part time Yamaha and Kawai organ technician and I can get the
old parts if I try.

http://www.flickr.com/photos/11236051@N08/sets/72157601399254969/

Allen

They look just like pictures 1 and 2 but mine are 45mm travel - yours
look like 30mm. I already put the machine back together but I have
limited functionality on the attack slider. See Below where Mr. Masta
approves a switch to 100K and a cap change by a similar factor of 20.
I could go either way.

rK

 

[rabiticide]

It's linear. But now I have another problem: The attack slider works
but is a little scratchy, so I'd like to replace it now that I've got
it pulled off the board. It is designated as "2MA" Nothing I can find
has such high resistance. I don't know why they would design it this
way.

Sorry, but is is not very helpful. Is it possible at all for you to post
a picture somewhere? Either on your ISP's "personal webspace" (every ISP
I've had has provide a personal page of maybe 10 MB.) or one of those
free photo hosts.

And also, for some reason I don't trust those numbers - they could be
house numbers and I don't know if _anybody_ has ever heard of a 2M
slider. Would you ohm them out? Or are they blown already? Is the
company still in business? Could you ask them for a parts list, or
even order replacements? Is there a Sams PhotoFact for it?

Cheers!
Rich

check out the diagram at http://rabbitshead.blogspot.com - I am afraid
it is actually 2Mohm Audio. The service manual and my measurements
confirm this. It is a Korg and they are still in business but the guy
on the phone never heard of a Korg Delta, then he consulted someone,
came back on and told me that was way too old for them to deal with,
would I like to buy something new?

anyway, I put it back together because I was impatient to play the
thing. The attack slider works through the first half of travel and I
can't imagine I'll need the back half. I am happy with it and I will
try to post sound samples later today...

rK