Alto L12 mixer, only 2007

[N_Cook]

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]

On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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.

 

[N_Cook]

Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...

On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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]

N_Cook <diverse@tcp.co.uk> wrote in message
news:gkqlu7$ejd$1@news.motzarella.org...

Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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

 

[Ron]

N_Cook wrote:

N_Cook <diverse@tcp.co.uk> wrote in message
news:gkqlu7$ejd$1@news.motzarella.org...
Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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

 

[N_Cook]

Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...

On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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/

 

[N_Cook]

Ron <ron@lunevalleyaudio.com> wrote in message
news:u8mdnf50p_cLc-3UnZ2dneKdnZydnZ2d@bt.com...

N_Cook wrote:
N_Cook <diverse@tcp.co.uk> wrote in message
news:gkqlu7$ejd$1@news.motzarella.org...
Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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/

 

[Ron]

N_Cook wrote:

Ron <ron@lunevalleyaudio.com> wrote in message
news:u8mdnf50p_cLc-3UnZ2dneKdnZydnZ2d@bt.com...
N_Cook wrote:
N_Cook <diverse@tcp.co.uk> wrote in message
news:gkqlu7$ejd$1@news.motzarella.org...
Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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

 

[Gareth Magennis]

"Ron" <ron@lunevalleyaudio.com> wrote in message
news:bYSdndQlA4A0JuzUnZ2dnUVZ8oGdnZ2d@bt.com...

N_Cook wrote:
Ron <ron@lunevalleyaudio.com> wrote in message
news:u8mdnf50p_cLc-3UnZ2dneKdnZydnZ2d@bt.com...
N_Cook wrote:
N_Cook <diverse@tcp.co.uk> wrote in message
news:gkqlu7$ejd$1@news.motzarella.org...
Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook"
diverse@tcp.co.uk>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.

 

[Eeyore]

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

 

[Eeyore]

N_Cook wrote:

Ron <ron@lunevalleyaudio.com> wrote

Have you tried Rapid Online, CPC or Canfords?

I long since stopped wasting my time on such activities.

IGNORANT MORON.

Graham

 

[Eeyore]

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

 

[Eeyore]

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/potentiometer-slide-10k/dp/1191728

Graham

 

[Meat Plow]

On Fri, 16 Jan 2009 23:10:04 -0000, "N_Cook" <diverse@tcp.co.uk>wrote:

Meat Plow <meat@petitmorte.net> wrote in message
news:2gn7b9.pvo.19.3@news.alt.net...
On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk>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.

Yah I figured this to be the case. Good luck with the fudge

 

[Dave M]

On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk> 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_folders/potsecrets/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!!

 

[N_Cook]

Dave M <masondg4xx4@cxxomcast.net> wrote in message
news:g5p4n4h5e4ru0p5jg9sqafe6ugcugjrnrq@4ax.com...

On Fri, 16 Jan 2009 17:27:46 -0000, "N_Cook" <diverse@tcp.co.uk> 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_folders/potsecrets/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/

 

[N_Cook]

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/

 

[Eeyore]

Dave M wrote:

You might look at some of the suggestions at
http://www.geofex.com/article_folders/potsecrets/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 fucking 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

 

[Eeyore]

Ron wrote:

N_Cook wrote:

I now always go for fudged work arounds.

Speechless!

Clueless !

Graham

 

[Eeyore]

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