Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Ten years ago I would have considered it impractical or even immoral.
But having to replace yet another effectively all plastic 12 mm pot because
the wiper is almost invisible in thickness, perhaps time for a rethink.
This type of pot has a metal covering but its only function is as a shroud
for fixing to the board, not even earthed, it does not strengthen the pot
body to restrain abuse at the other, user end. No longer are such pots fixed
to the front pannel.
I'm thinking that with the next one to replace it will be with a standard
small 12 mm or so enclosed preset that takes a standard plastic shaft in the
adjustment slot, fudging the other end of the shaft to take the knob and
through pannel bearer. The internal mechanism is just a pro-rata scaled down
conventional paxolin backed track with double wiper nibs.
If this replacement physically breaks in use then that seems more
justifiable than the modern flimsy wipers losing spring action or just aging
of the lubricant inside to wedge under the wiper and loose contact or
whatever their problem is, the tracks are always perfect (so little wiper
pressure presumably).
Are the resistive tracks of presets more frail/easier scoored than pot
tracks, so for that reason cannot be used say for volume control ?
Anyone any opinions?

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



  #2   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"N Cook" wrote in message
...
Ten years ago I would have considered it impractical or even immoral.
But having to replace yet another effectively all plastic 12 mm pot
because
the wiper is almost invisible in thickness, perhaps time for a rethink.
This type of pot has a metal covering but its only function is as a shroud
for fixing to the board, not even earthed, it does not strengthen the pot
body to restrain abuse at the other, user end. No longer are such pots
fixed
to the front pannel.
I'm thinking that with the next one to replace it will be with a standard
small 12 mm or so enclosed preset that takes a standard plastic shaft in
the
adjustment slot, fudging the other end of the shaft to take the knob and
through pannel bearer. The internal mechanism is just a pro-rata scaled
down
conventional paxolin backed track with double wiper nibs.
If this replacement physically breaks in use then that seems more
justifiable than the modern flimsy wipers losing spring action or just
aging
of the lubricant inside to wedge under the wiper and loose contact or
whatever their problem is, the tracks are always perfect (so little wiper
pressure presumably).
Are the resistive tracks of presets more frail/easier scoored than pot
tracks, so for that reason cannot be used say for volume control ?
Anyone any opinions?

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


I would have said that the description " preset " tells you all that you
need to know on that score. These components are designed to be set and
left, pretty much for the lifetime of the equipment, so I can't see them
standing up to the rigours of regular use for long. Add to this that as they
are not designed to be rotated repeatedly as a user control, the wiper /
track interface has not been designed to be specifically quiet. I also think
that the control will feel bad to a user, as it will not have that "
stirring treacle " feel that a proper user control has, courtesy of the drag
grease that the manufacturers put in the spindle bush. Why not replace
controls with manufacturer's originals ? Most group amp builders supply
spare parts. Failing that, there are plenty of reasonable quality pots
available - even the range that Maplin keep are pretty fair quality - and if
you really want to fit top quality pots, these are also available from
audiophile outlets.

Arfa


  #3   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Arfa Daily wrote in message
...

"N Cook" wrote in message
...
Ten years ago I would have considered it impractical or even immoral.
But having to replace yet another effectively all plastic 12 mm pot
because
the wiper is almost invisible in thickness, perhaps time for a rethink.
This type of pot has a metal covering but its only function is as a

shroud
for fixing to the board, not even earthed, it does not strengthen the

pot
body to restrain abuse at the other, user end. No longer are such pots
fixed
to the front pannel.
I'm thinking that with the next one to replace it will be with a

standard
small 12 mm or so enclosed preset that takes a standard plastic shaft in
the
adjustment slot, fudging the other end of the shaft to take the knob and
through pannel bearer. The internal mechanism is just a pro-rata scaled
down
conventional paxolin backed track with double wiper nibs.
If this replacement physically breaks in use then that seems more
justifiable than the modern flimsy wipers losing spring action or just
aging
of the lubricant inside to wedge under the wiper and loose contact or
whatever their problem is, the tracks are always perfect (so little

wiper
pressure presumably).
Are the resistive tracks of presets more frail/easier scoored than pot
tracks, so for that reason cannot be used say for volume control ?
Anyone any opinions?

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


I would have said that the description " preset " tells you all that you
need to know on that score. These components are designed to be set and
left, pretty much for the lifetime of the equipment, so I can't see them
standing up to the rigours of regular use for long. Add to this that as

they
are not designed to be rotated repeatedly as a user control, the wiper /
track interface has not been designed to be specifically quiet. I also

think
that the control will feel bad to a user, as it will not have that "
stirring treacle " feel that a proper user control has, courtesy of the

drag
grease that the manufacturers put in the spindle bush. Why not replace
controls with manufacturer's originals ? Most group amp builders supply
spare parts. Failing that, there are plenty of reasonable quality pots
available - even the range that Maplin keep are pretty fair quality - and

if
you really want to fit top quality pots, these are also available from
audiophile outlets.

Arfa



I had not considered the feel, which agreed is very 'scratchy'.
Squirting silicone oil in one and turning back and forth a hundred times is
very much improved, and resistive track still ok.
What is the point of the feather-light touch of the flimsy pots if the
downside is they just don't last.
I don't see the point of replacing with an exact match when the original is
say one of 8 and has only lasted for use once a week for 2 years before
internally failing , ie not abuse. In fact they seem to be the pots that are
not used much if at all, that's why I suspect clumping or something in the
lubricant.
I'll try a 1000 times and re-measure to see if the track fails.

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



  #4   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"N Cook" wrote in message
...
Arfa Daily wrote in message
...

"N Cook" wrote in message
...
Ten years ago I would have considered it impractical or even immoral.
But having to replace yet another effectively all plastic 12 mm pot
because
the wiper is almost invisible in thickness, perhaps time for a rethink.
This type of pot has a metal covering but its only function is as a

shroud
for fixing to the board, not even earthed, it does not strengthen the

pot
body to restrain abuse at the other, user end. No longer are such pots
fixed
to the front pannel.
I'm thinking that with the next one to replace it will be with a

standard
small 12 mm or so enclosed preset that takes a standard plastic shaft
in
the
adjustment slot, fudging the other end of the shaft to take the knob
and
through pannel bearer. The internal mechanism is just a pro-rata scaled
down
conventional paxolin backed track with double wiper nibs.
If this replacement physically breaks in use then that seems more
justifiable than the modern flimsy wipers losing spring action or just
aging
of the lubricant inside to wedge under the wiper and loose contact or
whatever their problem is, the tracks are always perfect (so little

wiper
pressure presumably).
Are the resistive tracks of presets more frail/easier scoored than pot
tracks, so for that reason cannot be used say for volume control ?
Anyone any opinions?

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


I would have said that the description " preset " tells you all that you
need to know on that score. These components are designed to be set and
left, pretty much for the lifetime of the equipment, so I can't see them
standing up to the rigours of regular use for long. Add to this that as

they
are not designed to be rotated repeatedly as a user control, the wiper /
track interface has not been designed to be specifically quiet. I also

think
that the control will feel bad to a user, as it will not have that "
stirring treacle " feel that a proper user control has, courtesy of the

drag
grease that the manufacturers put in the spindle bush. Why not replace
controls with manufacturer's originals ? Most group amp builders supply
spare parts. Failing that, there are plenty of reasonable quality pots
available - even the range that Maplin keep are pretty fair quality - and

if
you really want to fit top quality pots, these are also available from
audiophile outlets.

Arfa



I had not considered the feel, which agreed is very 'scratchy'.
Squirting silicone oil in one and turning back and forth a hundred times
is
very much improved, and resistive track still ok.
What is the point of the feather-light touch of the flimsy pots if the
downside is they just don't last.
I don't see the point of replacing with an exact match when the original
is
say one of 8 and has only lasted for use once a week for 2 years before
internally failing , ie not abuse. In fact they seem to be the pots that
are
not used much if at all, that's why I suspect clumping or something in the
lubricant.
I'll try a 1000 times and re-measure to see if the track fails.

--


I'm actually really surprised that you seem to come across so many bad pots
in group amps. I have been repairing these for many many years, and do lots
of all makes and models, for a local shop, and I really don't have to
replace many pots that aren't physically broken through taking knocks. I
have found in general, that most manufacturers appreciate that this gear is
going to last its owners for a lot of years, and tailor their design
criteria, and component spec-ing to suit. I would agree that the pots fitted
these days tend to be Japanese ( probably Chinese actually ) small-bodied
types, which are not as good quality as say the large body Wellyns or the
typical RS components pots that you used to find in them a few years back,
but still, I don't seem to have that much trouble with them. If you really
think that the problem is insufficient spring tension on the wiper fingers,
just pile a bit more on. It's easily done with a pair of long-nosed pointy
surgical tweezers.

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





  #5   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Arfa Daily wrote in message
...

"N Cook" wrote in message
...
Arfa Daily wrote in message
...

"N Cook" wrote in message
...
Ten years ago I would have considered it impractical or even immoral.
But having to replace yet another effectively all plastic 12 mm pot
because
the wiper is almost invisible in thickness, perhaps time for a

rethink.
This type of pot has a metal covering but its only function is as a

shroud
for fixing to the board, not even earthed, it does not strengthen the

pot
body to restrain abuse at the other, user end. No longer are such

pots
fixed
to the front pannel.
I'm thinking that with the next one to replace it will be with a

standard
small 12 mm or so enclosed preset that takes a standard plastic shaft
in
the
adjustment slot, fudging the other end of the shaft to take the knob
and
through pannel bearer. The internal mechanism is just a pro-rata

scaled
down
conventional paxolin backed track with double wiper nibs.
If this replacement physically breaks in use then that seems more
justifiable than the modern flimsy wipers losing spring action or

just
aging
of the lubricant inside to wedge under the wiper and loose contact or
whatever their problem is, the tracks are always perfect (so little

wiper
pressure presumably).
Are the resistive tracks of presets more frail/easier scoored than

pot
tracks, so for that reason cannot be used say for volume control ?
Anyone any opinions?

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


I would have said that the description " preset " tells you all that

you
need to know on that score. These components are designed to be set and
left, pretty much for the lifetime of the equipment, so I can't see

them
standing up to the rigours of regular use for long. Add to this that as

they
are not designed to be rotated repeatedly as a user control, the wiper

/
track interface has not been designed to be specifically quiet. I also

think
that the control will feel bad to a user, as it will not have that "
stirring treacle " feel that a proper user control has, courtesy of the

drag
grease that the manufacturers put in the spindle bush. Why not replace
controls with manufacturer's originals ? Most group amp builders supply
spare parts. Failing that, there are plenty of reasonable quality pots
available - even the range that Maplin keep are pretty fair quality -

and
if
you really want to fit top quality pots, these are also available from
audiophile outlets.

Arfa



I had not considered the feel, which agreed is very 'scratchy'.
Squirting silicone oil in one and turning back and forth a hundred times
is
very much improved, and resistive track still ok.
What is the point of the feather-light touch of the flimsy pots if the
downside is they just don't last.
I don't see the point of replacing with an exact match when the original
is
say one of 8 and has only lasted for use once a week for 2 years before
internally failing , ie not abuse. In fact they seem to be the pots that
are
not used much if at all, that's why I suspect clumping or something in

the
lubricant.
I'll try a 1000 times and re-measure to see if the track fails.

--


I'm actually really surprised that you seem to come across so many bad

pots
in group amps. I have been repairing these for many many years, and do

lots
of all makes and models, for a local shop, and I really don't have to
replace many pots that aren't physically broken through taking knocks. I
have found in general, that most manufacturers appreciate that this gear

is
going to last its owners for a lot of years, and tailor their design
criteria, and component spec-ing to suit. I would agree that the pots

fitted
these days tend to be Japanese ( probably Chinese actually ) small-bodied
types, which are not as good quality as say the large body Wellyns or the
typical RS components pots that you used to find in them a few years back,
but still, I don't seem to have that much trouble with them. If you really
think that the problem is insufficient spring tension on the wiper

fingers,
just pile a bit more on. It's easily done with a pair of long-nosed pointy
surgical tweezers.

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






The present problematic is a Carvin Pro Bass 100, PB100 which will come
bouncing back next weekend.
The new fault , could well be due to another pot failed, symptoms over the
phone so far, the previous one I replaced is fine.
I still have the previous original one lying around .
No makers name , a logo like cross-section of a flying saucer, a thin elipse
laid over a circle, just the outermost lineforms.
The wiper is only 0.15 mm thick , 0.6mm wide and using a force gauge, it
starts deflecting at only 12 grams pressure.

Followup on my endurance test on a preset, I survived 1000 turns back and
forth , whole track, as did the pot. No wavering on mid-track resistance
readings. The rough feel has returned but I doubt that is due to the wiper
action. Cracking it open, one obvious shiny, but not broken through to
paxolin, track from one nib and vague partial thin trace from the other nib.
I would estimate it could have done more than 10,000 rotations before both
tracks were worn through.

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





  #6   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"N Cook" wrote in message
...
Arfa Daily wrote in message
...

"N Cook" wrote in message
...
Arfa Daily wrote in message
...

"N Cook" wrote in message
...
Ten years ago I would have considered it impractical or even
immoral.
But having to replace yet another effectively all plastic 12 mm pot
because
the wiper is almost invisible in thickness, perhaps time for a

rethink.
This type of pot has a metal covering but its only function is as a
shroud
for fixing to the board, not even earthed, it does not strengthen
the
pot
body to restrain abuse at the other, user end. No longer are such

pots
fixed
to the front pannel.
I'm thinking that with the next one to replace it will be with a
standard
small 12 mm or so enclosed preset that takes a standard plastic
shaft
in
the
adjustment slot, fudging the other end of the shaft to take the knob
and
through pannel bearer. The internal mechanism is just a pro-rata

scaled
down
conventional paxolin backed track with double wiper nibs.
If this replacement physically breaks in use then that seems more
justifiable than the modern flimsy wipers losing spring action or

just
aging
of the lubricant inside to wedge under the wiper and loose contact
or
whatever their problem is, the tracks are always perfect (so little
wiper
pressure presumably).
Are the resistive tracks of presets more frail/easier scoored than

pot
tracks, so for that reason cannot be used say for volume control ?
Anyone any opinions?

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


I would have said that the description " preset " tells you all that

you
need to know on that score. These components are designed to be set
and
left, pretty much for the lifetime of the equipment, so I can't see

them
standing up to the rigours of regular use for long. Add to this that
as
they
are not designed to be rotated repeatedly as a user control, the wiper

/
track interface has not been designed to be specifically quiet. I also
think
that the control will feel bad to a user, as it will not have that "
stirring treacle " feel that a proper user control has, courtesy of
the
drag
grease that the manufacturers put in the spindle bush. Why not replace
controls with manufacturer's originals ? Most group amp builders
supply
spare parts. Failing that, there are plenty of reasonable quality pots
available - even the range that Maplin keep are pretty fair quality -

and
if
you really want to fit top quality pots, these are also available from
audiophile outlets.

Arfa



I had not considered the feel, which agreed is very 'scratchy'.
Squirting silicone oil in one and turning back and forth a hundred
times
is
very much improved, and resistive track still ok.
What is the point of the feather-light touch of the flimsy pots if the
downside is they just don't last.
I don't see the point of replacing with an exact match when the
original
is
say one of 8 and has only lasted for use once a week for 2 years before
internally failing , ie not abuse. In fact they seem to be the pots
that
are
not used much if at all, that's why I suspect clumping or something in

the
lubricant.
I'll try a 1000 times and re-measure to see if the track fails.

--


I'm actually really surprised that you seem to come across so many bad

pots
in group amps. I have been repairing these for many many years, and do

lots
of all makes and models, for a local shop, and I really don't have to
replace many pots that aren't physically broken through taking knocks. I
have found in general, that most manufacturers appreciate that this gear

is
going to last its owners for a lot of years, and tailor their design
criteria, and component spec-ing to suit. I would agree that the pots

fitted
these days tend to be Japanese ( probably Chinese actually ) small-bodied
types, which are not as good quality as say the large body Wellyns or the
typical RS components pots that you used to find in them a few years
back,
but still, I don't seem to have that much trouble with them. If you
really
think that the problem is insufficient spring tension on the wiper

fingers,
just pile a bit more on. It's easily done with a pair of long-nosed
pointy
surgical tweezers.

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






The present problematic is a Carvin Pro Bass 100, PB100 which will come
bouncing back next weekend.
The new fault , could well be due to another pot failed, symptoms over the
phone so far, the previous one I replaced is fine.
I still have the previous original one lying around .
No makers name , a logo like cross-section of a flying saucer, a thin
elipse
laid over a circle, just the outermost lineforms.
The wiper is only 0.15 mm thick , 0.6mm wide and using a force gauge, it
starts deflecting at only 12 grams pressure.

Followup on my endurance test on a preset, I survived 1000 turns back and
forth , whole track, as did the pot. No wavering on mid-track resistance
readings. The rough feel has returned but I doubt that is due to the wiper
action. Cracking it open, one obvious shiny, but not broken through to
paxolin, track from one nib and vague partial thin trace from the other
nib.
I would estimate it could have done more than 10,000 rotations before both
tracks were worn through.


In that case, go for it. I would be interested to know how you get on with
such transpants, and which presets you ultimately find most suitable. Also,
how quiet they are in actual practical usage.

Arfa


  #7   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 501
Default Anyone replace pots with presets ?

Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on with
such transpants, and which presets you ultimately find most suitable. Also,
how quiet they are in actual practical usage.

Arfa


I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)
  #8   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"Ron(UK)" wrote in message
...
Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa


I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)


Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the post
that started the thread, he says that he is intending using the presets that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but not
in a way that encourages him to *use* it. The shafts that I've seen usually
have a lightly splined finish so that they can be gripped, and a screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa


  #9   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Ron(UK) wrote in message
...
Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on

with
such transpants, and which presets you ultimately find most suitable.

Also,
how quiet they are in actual practical usage.

Arfa


I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)


I should have said the failed original in the 0.6mm was 2 wipers , the metal
is split into 2 wipers and nibs, absolutely no trace of wear on the track.

I have a few hundred Piher presets that have an enlarged slot to take rod
extenders with pair of pauls to engage the back of the slot, quite strong
enough to be used as unabused pots.
The very light action of the originals I would have thought were a
disadvantage, on stage, as you could easily dislodge a neighbouring pot.
Some of these Piher presets are log tracks, agreed unusual but useful

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



  #10   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 501
Default Anyone replace pots with presets ?

Arfa Daily wrote:
"Ron(UK)" wrote in message
...
Arfa Daily wrote:

In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa

I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)


Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the post
that started the thread, he says that he is intending using the presets that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but not
in a way that encourages him to *use* it. The shafts that I've seen usually
have a lightly splined finish so that they can be gripped, and a screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa




Ah ok, Piher do a range of shafts for their min presets. I`ve used them
on radio mike receivers etc. to replace the output level and squelch
controls, invariably because the user has been heavy handed with them.
The combined cost of preset and shaft is quite high compared with a
normal pot.

Personally I like the Omeg ECO plastic pots for replacements on gear
that takes standard quarter inch bore knobs, Rapid Electronics stock
the pots with the monkey metal slotted and splined short shaft that fits
a lot of the Chinese product

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com


  #11   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 2,770
Default Anyone replace pots with presets ?



"Ron(UK)" wrote:

Arfa Daily wrote:

In that case, go for it. I would be interested to know how you get on with
such transpants, and which presets you ultimately find most suitable. Also,
how quiet they are in actual practical usage.


I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?


Never IME.

Graham

  #12   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Ron(UK) wrote in message
...
Arfa Daily wrote:
"Ron(UK)" wrote in message
...
Arfa Daily wrote:

In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa
I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)


Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the

post
that started the thread, he says that he is intending using the presets

that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but

not
in a way that encourages him to *use* it. The shafts that I've seen

usually
have a lightly splined finish so that they can be gripped, and a

screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa




Ah ok, Piher do a range of shafts for their min presets. I`ve used them
on radio mike receivers etc. to replace the output level and squelch
controls, invariably because the user has been heavy handed with them.
The combined cost of preset and shaft is quite high compared with a
normal pot.

Personally I like the Omeg ECO plastic pots for replacements on gear
that takes standard quarter inch bore knobs, Rapid Electronics stock
the pots with the monkey metal slotted and splined short shaft that fits
a lot of the Chinese product

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com


If you mean the Vishay 12/13mm footprint pots then they are the right size
but the manufacturer's pdfs don't give the wiper dimensions , if of
thickness of a coarse human hair , 150 microns, then little point in using,
as will be back to square 1 in a few years.




  #13   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 501
Default Anyone replace pots with presets ?

N Cook wrote:
Ron(UK) wrote in message
...
Arfa Daily wrote:
"Ron(UK)" wrote in message
...
Arfa Daily wrote:

In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa
I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)
Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the

post
that started the thread, he says that he is intending using the presets

that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but

not
in a way that encourages him to *use* it. The shafts that I've seen

usually
have a lightly splined finish so that they can be gripped, and a

screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa



Ah ok, Piher do a range of shafts for their min presets. I`ve used them
on radio mike receivers etc. to replace the output level and squelch
controls, invariably because the user has been heavy handed with them.
The combined cost of preset and shaft is quite high compared with a
normal pot.

Personally I like the Omeg ECO plastic pots for replacements on gear
that takes standard quarter inch bore knobs, Rapid Electronics stock
the pots with the monkey metal slotted and splined short shaft that fits
a lot of the Chinese product

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com


If you mean the Vishay 12/13mm footprint pots then they are the right size
but the manufacturer's pdfs don't give the wiper dimensions , if of
thickness of a coarse human hair , 150 microns, then little point in using,
as will be back to square 1 in a few years.


I didn't, I meant Omeg, but the Vishay pots will certainly be better
than anything fitted as an original part by the vast majority of
manufacturers.

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com
  #14   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,572
Default Anyone replace pots with presets ?

Arfa Daily wrote:
"Ron(UK)" wrote in message
...

Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa


I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)



Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the post
that started the thread, he says that he is intending using the presets that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but not
in a way that encourages him to *use* it. The shafts that I've seen usually
have a lightly splined finish so that they can be gripped, and a screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa




It's really a moot point though. One can still buy very high quality
pots from a reputable manufacture. That's the route to take rather than
trying to hack in something different. A good pot will last the life of
most equipment. I use Bournes pots in arcade game controllers, they seem
to hold up well to the abuse.
  #15   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"James Sweet" wrote in message
news:tUgph.3163$Br.1752@trndny08...
Arfa Daily wrote:
"Ron(UK)" wrote in message
...

Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa

I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)



Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the
post that started the thread, he says that he is intending using the
presets that you can get a 6mm shaft for that turns them into a ( semi
?? ) user control - I'm sure you've seen the idea on stuff where there is
an adjustment that would be a good idea to have available to the user,
but not in a way that encourages him to *use* it. The shafts that I've
seen usually have a lightly splined finish so that they can be gripped,
and a screwdriver slot in the end. I think he intends to pass one of
these through a panel mount shaft bush, and then persuade the knob to
fit.

Arfa



It's really a moot point though. One can still buy very high quality pots
from a reputable manufacture. That's the route to take rather than trying
to hack in something different. A good pot will last the life of most
equipment. I use Bournes pots in arcade game controllers, they seem to
hold up well to the abuse.


Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.

Arfa




  #16   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 12,924
Default Anyone replace pots with presets ?

Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.



What do you mean by "Group equipment"?


BTW, http://potentiometer.com/ carries high end commercial & military
grade pots in the US.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
  #17   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 2,770
Default Anyone replace pots with presets ?



"Michael A. Terrell" wrote:

Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.


What do you mean by "Group equipment"?


Musical Instrument amplifiers and the like.

Graham

  #18   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

James Sweet wrote in message
news:tUgph.3163$Br.1752@trndny08...
Arfa Daily wrote:
"Ron(UK)" wrote in message
...

Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa

I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)



Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the

post
that started the thread, he says that he is intending using the presets

that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but

not
in a way that encourages him to *use* it. The shafts that I've seen

usually
have a lightly splined finish so that they can be gripped, and a

screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa




It's really a moot point though. One can still buy very high quality
pots from a reputable manufacture. That's the route to take rather than
trying to hack in something different. A good pot will last the life of
most equipment. I use Bournes pots in arcade game controllers, they seem
to hold up well to the abuse.


The thread concerns 12/13 mm footprint pots (sub miniature), no problem with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.


  #19   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 501
Default Anyone replace pots with presets ?

N Cook wrote:

The thread concerns 12/13 mm footprint pots (sub miniature), no problem with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.


One thing that concerns me about using a preset as a user control is the
'end stop' arrangement. Is the mechanism that prevents a user from
turning the control past it`s fully on or fully off position rugged
enough on a preset to to the job considering what heavy handed users
there sometimes are in the music business.

Also, if the end stop IS strong enough, is the mounting arrangement of a
preset strong enough to withstand the turning force of a typical death
metal guitarist after several pints of Krugermeister?



Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com
  #20   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"Michael A. Terrell" wrote in message
...
Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.



What do you mean by "Group equipment"?



Er, equipment used by groups ? Like bands ? Beatles, Rolling Stones ? Do you
not call them "groups" your side of the pond ? Never heard the term
"groupies" for the girls that follow them around ? In terms of this thread,
we have been talking specifically amplifiers for musical instruments, but in
general, at least over here, "group equipment" covers anything that a group
or band may be using on stage ( or off-stage ) to make their sound or image,
so amps, mixer desks, effects units / pedals, wireless mics, lighting
effects and so on. I know from our past
- errr ... 'conversations' shall we say - that you have been involved in the
repair of this equipment, so I'm sure that you probably have a valid opinion
on the substituting of panel-type pots with presets made into panel mounting
types ?? Back to you, friend ...

Arfa




  #21   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Ron(UK) wrote in message
...
N Cook wrote:

The thread concerns 12/13 mm footprint pots (sub miniature), no problem

with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.


One thing that concerns me about using a preset as a user control is the
'end stop' arrangement. Is the mechanism that prevents a user from
turning the control past it`s fully on or fully off position rugged
enough on a preset to to the job considering what heavy handed users
there sometimes are in the music business.

Also, if the end stop IS strong enough, is the mounting arrangement of a
preset strong enough to withstand the turning force of a typical death
metal guitarist after several pints of Krugermeister?



Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com


Thanks for that, I had not considered the end stops.
The original one, with the flimsey wiper, had quite manly endstop nib on the
shaft and housing moulding.
These presets have similar sized physical end stops, the weakest point would
be the two plastic pauls on the shaft that engage with the slot, about 3 x
1.5mm each in cross section.
I would mount the body to pcb with hot melt glue.
Guitarists and pot problems is usually the guitar controls where the fascia
is plastic so no reliable mounting, so the nuts loosen and pots are then
twisted round and round , windlassing the wires into a broken mess.
That problem I cure by heavy-soldering a thick copper strip between all the
pots, replacing the wire grounds between the pots

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





  #22   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 12,924
Default Anyone replace pots with presets ?

Arfa Daily wrote:

"Michael A. Terrell" wrote in message
...
Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.



What do you mean by "Group equipment"?



Er, equipment used by groups ? Like bands ? Beatles, Rolling Stones ? Do you
not call them "groups" your side of the pond ? Never heard the term
"groupies" for the girls that follow them around?



Groupie is a group of enthusiastic fans of any type, in the US.


In terms of this thread,
we have been talking specifically amplifiers for musical instruments, but in
general, at least over here, "group equipment" covers anything that a group
or band may be using on stage ( or off-stage ) to make their sound or image,
so amps, mixer desks, effects units / pedals, wireless mics, lighting
effects and so on.



They referred to them as bands, and their electronics as "Band Amps",
"Musical equipment" or "Guitar amps" when I was doing that work in the
'70s & '80s. Most repairs were done by part time techs at music stores,
but there was usually a
shop that specialized in amp repair in bigger cities. I even saw a few
british amps, back in the '70s when some clueless wanabes were trying to
copy one band or another, right down to the brand of wire and connectors
for their cables. The only thing they forgot was to learn how to play
music, sing, and perform in front of people who want good music. ;-)


I know from our past
- errr ... 'conversations' shall we say - that you have been involved in the
repair of this equipment, so I'm sure that you probably have a valid opinion
on the substituting of panel-type pots with presets made into panel mounting
types ?? Back to you, friend ...



As far as I am concerned, panel mounted controls are the only way to
go for any application that involves rugged service. PC mounted are ok
for internal adjustment, but nothing beats a mil spec made to last for
25 years of daily use.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
  #23   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,572
Default Anyone replace pots with presets ?



The thread concerns 12/13 mm footprint pots (sub miniature), no problem with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.





What difference does it make? Cheap pots are cheap pots. I was
originally using ones from Radio Shack, but those were not holding up
even to home use.
  #24   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 110
Default Anyone replace pots with presets ?

Seems kind of unlikely that equipment like that would get a lot of wear
from the pots being adjusted back and forth. Could it be that vibration
from the speakers is tearing up the pots in the head? Maybe the PC board
and front panel lack the mechanical dampening to protect this from
happening.

N Cook wrote:








The present problematic is a Carvin Pro Bass 100, PB100 which will come
bouncing back next weekend.
The new fault , could well be due to another pot failed, symptoms over the
phone so far, the previous one I replaced is fine.
I still have the previous original one lying around .
No makers name , a logo like cross-section of a flying saucer, a thin elipse
laid over a circle, just the outermost lineforms.
The wiper is only 0.15 mm thick , 0.6mm wide and using a force gauge, it
starts deflecting at only 12 grams pressure.

Followup on my endurance test on a preset, I survived 1000 turns back and
forth , whole track, as did the pot. No wavering on mid-track resistance
readings. The rough feel has returned but I doubt that is due to the wiper
action. Cracking it open, one obvious shiny, but not broken through to
paxolin, track from one nib and vague partial thin trace from the other nib.
I would estimate it could have done more than 10,000 rotations before both
tracks were worn through.

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






--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

  #25   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 110
Default Anyone replace pots with presets ?

That explains the problem. What he needs to do is follow the group out
to the "Gig". He doesn't need to be there from the start, rather at the
end when the group finishes up by smashing their guitars and mike stands
into his rental amplifiers!

Eeyore wrote:

"Michael A. Terrell" wrote:



Arfa Daily wrote:


Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.


What do you mean by "Group equipment"?



Musical Instrument amplifiers and the like.

Graham



That explains the problem. What he needs to do is follow the group out
to the "Gig". He doesn't need to be there from the start, rather at the
end when the group finishes up by smashing their guitars and mike stands
into his rental amplifiers!

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P





  #26   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

**THE-RFI-EMI-GUY** wrote in message
...
Seems kind of unlikely that equipment like that would get a lot of wear
from the pots being adjusted back and forth. Could it be that vibration
from the speakers is tearing up the pots in the head? Maybe the PC board
and front panel lack the mechanical dampening to protect this from
happening.

N Cook wrote:








The present problematic is a Carvin Pro Bass 100, PB100 which will come
bouncing back next weekend.
The new fault , could well be due to another pot failed, symptoms over

the
phone so far, the previous one I replaced is fine.
I still have the previous original one lying around .
No makers name , a logo like cross-section of a flying saucer, a thin

elipse
laid over a circle, just the outermost lineforms.
The wiper is only 0.15 mm thick , 0.6mm wide and using a force gauge, it
starts deflecting at only 12 grams pressure.

Followup on my endurance test on a preset, I survived 1000 turns back and
forth , whole track, as did the pot. No wavering on mid-track resistance
readings. The rough feel has returned but I doubt that is due to the

wiper
action. Cracking it open, one obvious shiny, but not broken through to
paxolin, track from one nib and vague partial thin trace from the other

nib.
I would estimate it could have done more than 10,000 rotations before

both
tracks were worn through.

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






--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P


Its not a wear problem , in my opinion.
There is absolutely no wear on the track , the problem is due to too flimsy
a wiper, half an ounce of pressure is enough to start lifting the wiper, ie
only age-thickened lubricant grease inside is enough to do that.


  #27   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"N Cook" wrote in message
...
**THE-RFI-EMI-GUY** wrote in message
...
Seems kind of unlikely that equipment like that would get a lot of wear
from the pots being adjusted back and forth. Could it be that vibration
from the speakers is tearing up the pots in the head? Maybe the PC board
and front panel lack the mechanical dampening to protect this from
happening.

N Cook wrote:








The present problematic is a Carvin Pro Bass 100, PB100 which will come
bouncing back next weekend.
The new fault , could well be due to another pot failed, symptoms over

the
phone so far, the previous one I replaced is fine.
I still have the previous original one lying around .
No makers name , a logo like cross-section of a flying saucer, a thin

elipse
laid over a circle, just the outermost lineforms.
The wiper is only 0.15 mm thick , 0.6mm wide and using a force gauge, it
starts deflecting at only 12 grams pressure.

Followup on my endurance test on a preset, I survived 1000 turns back
and
forth , whole track, as did the pot. No wavering on mid-track resistance
readings. The rough feel has returned but I doubt that is due to the

wiper
action. Cracking it open, one obvious shiny, but not broken through to
paxolin, track from one nib and vague partial thin trace from the other

nib.
I would estimate it could have done more than 10,000 rotations before

both
tracks were worn through.

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






--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P


Its not a wear problem , in my opinion.
There is absolutely no wear on the track , the problem is due to too
flimsy
a wiper, half an ounce of pressure is enough to start lifting the wiper,
ie
only age-thickened lubricant grease inside is enough to do that.



But surely that's the age-old problem of any pot ? Isn't that why we all
squib decent quality switch cleaner into pot bodies ? The volatile component
of this dissolves and washes out the hardened grease, whilst the lubricant
component recoats the track. Thinking about your statements regarding wiper
pressure. The wiper has to have reasonably light contact with the track in a
user-intended control, otherwise constant adjustment, would wear the track.
It seems to me that a half ounce of contact pressure, is quite a lot ? For
sure, the big old clunky pots that were fitted to gear 40 years ago,
probably had a wiper the size of your hand that pressed on a track as thick
as your finger with a pressure of half a pound, but times and manufacturing
techniques move on. Just exactly what problems do you seem to get with all
these pots, that won't fix with a shot of Electrolube ? With the shaft
encoders that many hifi's use now for volume control, I've found that the
grease which appears on the encoder disc, and stops then from working, is
the treacle-stir-feel grease that they put in the shaft bearing, which has
migrated down into the main body. The wipers in these devices are like
feathers, and very delicate, but once they are cleaned out, and relubed with
a proper contact lubricant, they don't give any more trouble - in fact I
can't recall ever having one thus treated, bounce back on me.

Arfa


  #28   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 501
Default Anyone replace pots with presets ?

N Cook wrote:


Its not a wear problem , in my opinion.
There is absolutely no wear on the track , the problem is due to too flimsy
a wiper, half an ounce of pressure is enough to start lifting the wiper, ie
only age-thickened lubricant grease inside is enough to do that.


It`s the age old problem of cheap nasty low cost components being used,
even in some equipment perceived as being of high status. You CAN buy
decent pots if you shop around, or use normal replacement pots and add a
drop of electrolube to the track before you solder it in.

I wouldn`t advise changing too many components in some muso`s vintage
gear, some of these valve amp afficionados get shirty if you replace
faulty resistors with modern types that 'don't look right' I hate to
think what they`d say if you added a bodged up pot


Ron(UK)
  #29   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

I'm coming round to thinking that as these pots are easily openable and
there is no wear at all on the tracks, then clean out all the lubricant with
meths or something, coat the wiper with something to stiffen it up a bit and
re-assemble, with no lubricant at all, maybe just "dry lubricant" of fine
graphite powder laid in the track area instead.

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




  #30   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Arfa Daily wrote in message
...

"N Cook" wrote in message
...
**THE-RFI-EMI-GUY** wrote in message
...
Seems kind of unlikely that equipment like that would get a lot of wear
from the pots being adjusted back and forth. Could it be that vibration
from the speakers is tearing up the pots in the head? Maybe the PC

board
and front panel lack the mechanical dampening to protect this from
happening.

N Cook wrote:








The present problematic is a Carvin Pro Bass 100, PB100 which will

come
bouncing back next weekend.
The new fault , could well be due to another pot failed, symptoms over

the
phone so far, the previous one I replaced is fine.
I still have the previous original one lying around .
No makers name , a logo like cross-section of a flying saucer, a thin

elipse
laid over a circle, just the outermost lineforms.
The wiper is only 0.15 mm thick , 0.6mm wide and using a force gauge,

it
starts deflecting at only 12 grams pressure.

Followup on my endurance test on a preset, I survived 1000 turns back
and
forth , whole track, as did the pot. No wavering on mid-track

resistance
readings. The rough feel has returned but I doubt that is due to the

wiper
action. Cracking it open, one obvious shiny, but not broken through to
paxolin, track from one nib and vague partial thin trace from the

other
nib.
I would estimate it could have done more than 10,000 rotations before

both
tracks were worn through.

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






--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P


Its not a wear problem , in my opinion.
There is absolutely no wear on the track , the problem is due to too
flimsy
a wiper, half an ounce of pressure is enough to start lifting the wiper,
ie
only age-thickened lubricant grease inside is enough to do that.



But surely that's the age-old problem of any pot ? Isn't that why we all
squib decent quality switch cleaner into pot bodies ? The volatile

component
of this dissolves and washes out the hardened grease, whilst the lubricant
component recoats the track. Thinking about your statements regarding

wiper
pressure. The wiper has to have reasonably light contact with the track in

a
user-intended control, otherwise constant adjustment, would wear the

track.
It seems to me that a half ounce of contact pressure, is quite a lot ? For
sure, the big old clunky pots that were fitted to gear 40 years ago,
probably had a wiper the size of your hand that pressed on a track as

thick
as your finger with a pressure of half a pound, but times and

manufacturing
techniques move on. Just exactly what problems do you seem to get with all
these pots, that won't fix with a shot of Electrolube ? With the shaft
encoders that many hifi's use now for volume control, I've found that the
grease which appears on the encoder disc, and stops then from working, is
the treacle-stir-feel grease that they put in the shaft bearing, which has
migrated down into the main body. The wipers in these devices are like
feathers, and very delicate, but once they are cleaned out, and relubed

with
a proper contact lubricant, they don't give any more trouble - in fact I
can't recall ever having one thus treated, bounce back on me.

Arfa



I'm not sure that aerosol lubricant would reliably get into these pots ,
there certainly isn't any slots and I would say the injection mouleded 2
components of the housing are tight fitting. There is still the sludgy
lubricant grease inside.

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






  #31   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 6,772
Default Anyone replace pots with presets ?


"N Cook" wrote in message
...
I'm coming round to thinking that as these pots are easily openable and
there is no wear at all on the tracks, then clean out all the lubricant
with
meths or something, coat the wiper with something to stiffen it up a bit
and
re-assemble, with no lubricant at all, maybe just "dry lubricant" of fine
graphite powder laid in the track area instead.


Ah ! Same post appeared ( accidentally I guess ) in your "speaker power"
thread, so I say the same here -

There ya go then !

I also agree with Ron in respect of subbing parts in musos' gear. Looking
for trouble with some of them ...

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






  #32   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,220
Default Anyone replace pots with presets ?

Arfa Daily wrote in message
...

"N Cook" wrote in message
...
I'm coming round to thinking that as these pots are easily openable and
there is no wear at all on the tracks, then clean out all the lubricant
with
meths or something, coat the wiper with something to stiffen it up a bit
and
re-assemble, with no lubricant at all, maybe just "dry lubricant" of

fine
graphite powder laid in the track area instead.


Ah ! Same post appeared ( accidentally I guess ) in your "speaker power"
thread, so I say the same here -

There ya go then !

I also agree with Ron in respect of subbing parts in musos' gear. Looking
for trouble with some of them ...

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







Rushing around to go to a pyrotechnics lecture.
Interesting demonstratiion of a developemental stage pyrotechnic strobe
light, for chemistry , amazingly sharp cut-off, re-ignition, of about 4
flashes per second, intense flare strobe action


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Best way to clean Pots. Bob Urz Electronics Repair 2 December 19th 06 01:48 AM
Best way to clean Pots. Michael A. Terrell Electronics Repair 4 December 19th 06 01:45 AM
Best way to clean Pots. Jim Yanik Electronics Repair 0 December 18th 06 03:18 PM
Best way to clean Pots. Mark D. Zacharias Electronics Repair 0 December 18th 06 12:49 PM
Photocopier adjustment presets n cook Electronics Repair 3 August 30th 06 10:01 PM


All times are GMT +1. The time now is 05:33 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"