And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one that
there maybe enough space and can be screwed onto/under/through the top panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work around or
will the characteristic be too "lumpy" on the low end?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Meat Plow wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one
that
there maybe enough space and can be screwed onto/under/through the top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work around
or
will the characteristic be too "lumpy" on the low end?

I'd be surprised to see this as a suitable solution. Can you swipe a
pot from the last channel or are they different? I've done this in the
past when no alternative was available and the customer knew what to
expect.

I'd thought of that but to safely remove the failed one I will be grinding
off the mounting tangs, then desolder the active pins, as there is SM right
up against the pots. They are all similarly crammed in , but there is space
between the pcb mounted pots and the back face of the top panel.

I will plot out a 25:1 ratio fudged pot to see how removed it is from the
original 10K at 100 percent and 1K at 50 percent travel.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N_Cook wrote in message
...
Meat Plow wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one
that
there maybe enough space and can be screwed onto/under/through the top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work
around
or
will the characteristic be too "lumpy" on the low end?

I'd be surprised to see this as a suitable solution. Can you swipe a
pot from the last channel or are they different? I've done this in the
past when no alternative was available and the customer knew what to
expect.

I'd thought of that but to safely remove the failed one I will be grinding
off the mounting tangs, then desolder the active pins, as there is SM
right
up against the pots. They are all similarly crammed in , but there is
space
between the pcb mounted pots and the back face of the top panel.

I will plot out a 25:1 ratio fudged pot to see how removed it is from the
original 10K at 100 percent and 1K at 50 percent travel.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




or rather the value at 1percent and 5 percent comparisons and 90, 95
percent

N_Cook wrote:
N_Cook wrote in message
...
Meat Plow wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one
that
there maybe enough space and can be screwed onto/under/through the top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work
around
or
will the characteristic be too "lumpy" on the low end?
I'd be surprised to see this as a suitable solution. Can you swipe a
pot from the last channel or are they different? I've done this in the
past when no alternative was available and the customer knew what to
expect.
I'd thought of that but to safely remove the failed one I will be grinding
off the mounting tangs, then desolder the active pins, as there is SM
right
up against the pots. They are all similarly crammed in , but there is
space
between the pcb mounted pots and the back face of the top panel.

I will plot out a 25:1 ratio fudged pot to see how removed it is from the
original 10K at 100 percent and 1K at 50 percent travel.


Have you tried Rapid Online, CPC or Canfords?

Ron

Meat Plow wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one
that
there maybe enough space and can be screwed onto/under/through the top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work around
or
will the characteristic be too "lumpy" on the low end?

I'd be surprised to see this as a suitable solution. Can you swipe a
pot from the last channel or are they different? I've done this in the
past when no alternative was available and the customer knew what to
expect.


Yep , graphing it out the characteristic is hopeless. Matter of opening up
the pot and dabs of silver paint or a graphite compo along the tracks and a
pair of resistors looks necessary to bring it back to something like
functional equivalent.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Ron wrote in message
...
N_Cook wrote:
N_Cook wrote in message
...
Meat Plow wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one
that
there maybe enough space and can be screwed onto/under/through the
top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work
around
or
will the characteristic be too "lumpy" on the low end?
I'd be surprised to see this as a suitable solution. Can you swipe a
pot from the last channel or are they different? I've done this in the
past when no alternative was available and the customer knew what to
expect.
I'd thought of that but to safely remove the failed one I will be
grinding
off the mounting tangs, then desolder the active pins, as there is SM
right
up against the pots. They are all similarly crammed in , but there is
space
between the pcb mounted pots and the back face of the top panel.

I will plot out a 25:1 ratio fudged pot to see how removed it is from
the
original 10K at 100 percent and 1K at 50 percent travel.


Have you tried Rapid Online, CPC or Canfords?

Ron


I long since stopped wasting my time on such activities.
Right electrical characteristic but totally wrong dimensions or vice versa
or minimum order requirements, main agents only , etc etc always a total
waste of time and/or money , I now always go for fudged work arounds.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N_Cook wrote:
Ron wrote in message
...
N_Cook wrote:
N_Cook wrote in message
...
Meat Plow wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one
that
there maybe enough space and can be screwed onto/under/through the
top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work
around
or
will the characteristic be too "lumpy" on the low end?
I'd be surprised to see this as a suitable solution. Can you swipe a
pot from the last channel or are they different? I've done this in the
past when no alternative was available and the customer knew what to
expect.
I'd thought of that but to safely remove the failed one I will be
grinding
off the mounting tangs, then desolder the active pins, as there is SM
right
up against the pots. They are all similarly crammed in , but there is
space
between the pcb mounted pots and the back face of the top panel.

I will plot out a 25:1 ratio fudged pot to see how removed it is from
the
original 10K at 100 percent and 1K at 50 percent travel.

Have you tried Rapid Online, CPC or Canfords?

Ron


I long since stopped wasting my time on such activities.
Right electrical characteristic but totally wrong dimensions or vice versa
or minimum order requirements, main agents only , etc etc always a total
waste of time and/or money ,

I now always go for fudged work arounds.

Speechless!

Ron

"Ron" wrote in message
...
N_Cook wrote:
Ron wrote in message
...
N_Cook wrote:
N_Cook wrote in message
...
Meat Plow wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook"
wrote:

And the master slider pot has failed (Chinese so assume
unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger
one
that
there maybe enough space and can be screwed onto/under/through the
top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work
around
or
will the characteristic be too "lumpy" on the low end?
I'd be surprised to see this as a suitable solution. Can you swipe a
pot from the last channel or are they different? I've done this in
the
past when no alternative was available and the customer knew what to
expect.
I'd thought of that but to safely remove the failed one I will be
grinding
off the mounting tangs, then desolder the active pins, as there is SM
right
up against the pots. They are all similarly crammed in , but there is
space
between the pcb mounted pots and the back face of the top panel.

I will plot out a 25:1 ratio fudged pot to see how removed it is from
the
original 10K at 100 percent and 1K at 50 percent travel.

Have you tried Rapid Online, CPC or Canfords?

Ron


I long since stopped wasting my time on such activities.
Right electrical characteristic but totally wrong dimensions or vice
versa
or minimum order requirements, main agents only , etc etc always a total
waste of time and/or money ,

I now always go for fudged work arounds.

Speechless!

Ron



Splutter.

Anyway sometimes you can find manufacturers that will sell you faders for
their gear that are also found in other equipment. Like your Numarks, Kam,
Mackie, Behringer, Soundcraft etc etc. Get a few spare and you can
sometimes swap tracks or shafts where the fader isn't quite the same.
Stereo versions sometimes have the same footprint but just don't use half
the pins, so you can just get a few of those for all cases.

If there is really no way to replace a fader I tend to leave it at that,
rather than attempt a Bodgitt and Scarper repair. I won't do anything I
wouldn't want another tech to look at and go tch tch.




Gareth.

N_Cook wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one that
there maybe enough space and can be screwed onto/under/through the top panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work around or
will the characteristic be too "lumpy" on the low end?

Why are you ALWAYS so unknowledgable. I'll bet it'll take an ALPS or Taiwan
Alpha part.

What the effing travel of the thing to begin with ?

Graham

N_Cook wrote:

Ron wrote

Have you tried Rapid Online, CPC or Canfords?

I long since stopped wasting my time on such activities.

IGNORANT MORON.

Graham

N_Cook wrote:

Yep , graphing it out the characteristic is hopeless. Matter of opening up
the pot and dabs of silver paint or a graphite compo along the tracks and a
pair of resistors looks necessary to bring it back to something like
functional equivalent.

HOLY CRAP !

Graham

N_Cook wrote:

And the master slider pot has failed (Chinese so assume unavailable).

Why ? They use standard parts and you can contact Phonic.
http://www.phonic.com/

Does it look anything like this for example ?
http://uk.farnell.com/alps/rs601110k...10k/dp/1191728

Graham

On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one that
there maybe enough space and can be screwed onto/under/through the top panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work around or
will the characteristic be too "lumpy" on the low end?


You might look at some of the suggestions at
http://www.geofex.com/article_folder...s/potscret.htm and see if any of
them might offer a workable solution for you. I realize it will probably never
be an exact match for the original taper, but sometimes it can be worked out
really close.
Good luck
==============

Dave M

Never take a laxative and a sleeping pill at the same time!!

Dave M wrote in message
...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" wrote:

And the master slider pot has failed (Chinese so assume unavailable).
Long but tiny cross section stereo 2x 10K log pot. Found a larger one
that
there maybe enough space and can be screwed onto/under/through the top
panel
and wired into the pcb but it is 2x 250K lin of course.
10K and 1K resitors in parallel with each pot, will that be a work around
or
will the characteristic be too "lumpy" on the low end?


You might look at some of the suggestions at
http://www.geofex.com/article_folder...s/potscret.htm and see if
any of
them might offer a workable solution for you. I realize it will probably
never
be an exact match for the original taper, but sometimes it can be worked
out
really close.
Good luck
==============

Dave M

Never take a laxative and a sleeping pill at the same time!!


" * I have heard that you can use copier toner dust to melt over a
section of worn resistor material and repair it. "

probably referring to my tip for worn pots, fully detailed here

Dismantle the pot down to the carbon track clean/degrease.
Make up resistive compound from photocopier toner and graphite powder
obtainable from locksmiths for dry "lubrication".
the following resistivity values are very approximate for .02 inch thick
film.
graphite:toner ratios
1:1 ,200 ohm per square inch
1:10, 100k ohm per square inch
1:30 10M ohm per square inch
Mask off area surrounding carbon track,sprinkle on the powder,fuse the film
in a low oven approx 150 degrees centigrade or hold the barrel of a
soldering
iron 1mm from the powder to heat .When fused lightly abraid with a
nail file,and reassemble pot.High ohmic pots are a bit iffy,low ohmic are
fine.
p.s. I would be interested to hear of any suggestions for higher resistivity
addmixture for higher ohmic pots (for more even distribution)


Which I will probably use for this Chinese pot. the main problem with it is
not having a nice flat surface after "curing". Needs some sort of aqua
process perhaps to give an initial flat surface.
Aquadag or whatever EFI/EMI screening black (dries to slightly brown side of
black) stuff is , may be useful for very low ohm but probably too brittle
and does not adhere to impervious surfaces.
My can of it is too old to get product details RS stock number "551-570"
other than it contains MEK and xylene

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

I just thought of a possible way round the surface roughness.
Lay the resistive dust in place. Reaassemble the pot with the wiper at one
end and run the 3 wire fingers,of each wiper, along the track and then undo
the pot again. Then fuse the toner/graphite hopefully to something like
20Kohm and then add 1K and 20K (actual on test) resistors each side, .
Rather than 2 differing mixes of resistive dust on each track.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Dave M wrote:

You might look at some of the suggestions at
http://www.geofex.com/article_folder...s/potscret.htm and see if any of
them might offer a workable solution for you. I realize it will probably never
be an exact match for the original taper, but sometimes it can be worked out
really close.

It will be a ****ing audio 'A' JIS taper.

Likely manufacturers of this part are ALPS, Panasonic and Taiwan Alpha. Knowing
Phonic as I do, it's most likely a Taiwan Alpha part (they use lots of them and
they're cheap).

In all probability the master fader from a Soundcraft Spirit product will fit but
beware there are 2 common pinouts, so get one of each. Soundcraft spares should
know all about that.

Graham

Ron wrote:

N_Cook wrote:

I now always go for fudged work arounds.

Speechless!

Clueless !

Graham

N_Cook wrote:

" * I have heard that you can use copier toner dust to melt over a
section of worn resistor material and repair it. "

probably referring to my tip for worn pots, fully detailed here

Dismantle the pot down to the carbon track clean/degrease.
Make up resistive compound from photocopier toner and graphite powder
obtainable from locksmiths for dry "lubrication".
the following resistivity values are very approximate for .02 inch thick
film.
graphite:toner ratios
1:1 ,200 ohm per square inch
1:10, 100k ohm per square inch
1:30 10M ohm per square inch
Mask off area surrounding carbon track,sprinkle on the powder,fuse the film
in a low oven approx 150 degrees centigrade or hold the barrel of a
soldering
iron 1mm from the powder to heat .When fused lightly abraid with a
nail file,and reassemble pot.High ohmic pots are a bit iffy,low ohmic are
fine.
p.s. I would be interested to hear of any suggestions for higher resistivity
addmixture for higher ohmic pots (for more even distribution)

Which I will probably use for this Chinese pot. the main problem with it is
not having a nice flat surface after "curing". Needs some sort of aqua
process perhaps to give an initial flat surface.
Aquadag or whatever EFI/EMI screening black (dries to slightly brown side of
black) stuff is , may be useful for very low ohm but probably too brittle
and does not adhere to impervious surfaces.
My can of it is too old to get product details RS stock number "551-570"
other than it contains MEK and xylene

And all because you wont buy the correct right replacement part ? What kind of
moron are you ?

The damn manufacturer's name or logo should be on it btw.

I hate to think what the bill for this bodged repair will be.

Graham

Eeyore wrote:

N_Cook wrote:

And the master slider pot has failed (Chinese so assume unavailable).

Why ? They use standard parts and you can contact Phonic.
http://www.phonic.com/

Sorry, it was Alto.
http://www.altopa.com/default.asp
http://www.altopa.com/default.asp?p1=5&p2=32&p_id=35

Graham

All foregoing is now digression.

End-snipping and then grinding off the tinplate tangs before desoldering the
active pins is the way to deal with these , without colateral damage.
Getting inside, the non-resistive tracks are only 1mm wide and one pair of
single wiper "wires" must have been right on the edge of one such track so
intermittant contact, 1/2mm transverse bend and repaired.
Will resolder the remnant tinplate tangs for earthing and add hot-melt
around the housing where there is spaces.
All 9 of these sliders are the same, but no problem with a channel one going
U/S unless someone uses all channels, problem was of course, Murphy's law,
on the critical one..

Only info on the side is rather self evident 10KDx2.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

For future reference I had a go at adapting one of the linear 250K ohm
slider pots. I doubt if the following could be used for the narrow tracks
inside the Chinese one, but if space allows for a more conventional one as I
had anticipated doing.

With 2 narrow pieces of "masking tape" I laid one, leaving just the outside
edge of the 250K track exposed and another one on the paxolin, leaving a 2mm
strip un-masked .
Squirted out some "RFI/EMI" spray into a pot and then with a toothpick laid
down a thin line of aquadag, or whatever it is, along about 40 percent of
the track (for comparison purposes) . Silver paint would have done instead,
but just a prooving exercise.
When dried that measured 23 ohm , over its length, and about the same for
that portion of the pot track via the 2 relevant terminals.
With a razor made 3 cuts, so divided the aquadag track into quarters. Then
some nail varnish just over the aquadag and onto the remaining paxolin just
to confirm no adverse reaction and a suitable fixative and rassembled.
I suspect the characteristic would be a bit wavy rather than linear, if
properly plotted out, but results
5 percent 10 ohm
10 % 400 ohm
20% 1.8K
30% 8K
40% 42K
50% 66K
and then much as the original 120K to 250K of course

I didn't bother with the following, but
For the upper section, for a log characteristic, then lay down a full length
aquadag track and make more , closer spaced cuts, and also a 1K and 20K
resistors or whatever , to fit, external to the pot.
Other non-linear characteristics , other than log could be so fashioned. And
as the thickness of the aquadag track is not critical then rotational pots
could be so converted almost as easily. The only criteria are higher ohmic
value to start with than final requirement, low wattage and enough space to
lay down these extra tracks.
Another one for my tips files. The internet timewasters can continue their
predilictions and buy 1000 off from Hong Kong or whatever they have to do.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

The "aquadag" I used contains nickel and air drying acrylic resin

Closer checking with vernier calipers and DVM there was an abrupt jump at
23%,
from 1.5K to 3.4K, so not a perfect solution


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N_Cook wrote:

I just thought of a possible way round the surface roughness.
Lay the resistive dust in place. Reaassemble the pot with the wiper at one
end and run the 3 wire fingers,of each wiper, along the track and then undo
the pot again. Then fuse the toner/graphite hopefully to something like
20Kohm and then add 1K and 20K (actual on test) resistors each side, .
Rather than 2 differing mixes of resistive dust on each track.

For CHRIST'S SAKE buy the proper replacement part !

You STILL haven't answered the question about what the travel is in mm. 60mm
most likely IME. Dual 10kA sliders are available widely that'll fit. I think
there are only 2 popular footprints.

http://www3.alps.com/WebObjects/cata...ers_list1.html

Look at those 'low profile master types'. Soundcraft use them in the Spirit
range, so they can be obtained as spares from them.

Graham

N_Cook wrote:

The "aquadag" I used contains nickel and air drying acrylic resin

Closer checking with vernier calipers and DVM there was an abrupt jump at
23%,
from 1.5K to 3.4K, so not a perfect solution

How much are you going to charge this poor customer for an incompetent repair
?

Graham

N_Cook wrote:

Only info on the side is rather self evident 10KDx2.

ALPS D taper is 10% resistance at the centre (-20dB) as opposed to the more
popular A taper which is 15% (-17dB).

A virtual certainty it's an Alps part. Is the base also white plastic ?

Graham

N_Cook wrote:

And the master slider pot has failed

Does it look a bit like this ? Wrong length in the pic and only mono but this is
basically the kind of part.

http://cgi.ebay.co.uk/Slide-Potentio...QQcmdZViewItem

Graham