poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy them.

TIA
JimK

On Aug 30, 7:38*pm, jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy *them.

TIA
JimK

If you can solder its perfectly doable, assuming its not an oddity
with custom pots. I once had an amp with a 4 gang volume pot with
centre taps - no chance of replacement!


NT

NT wrote:

If you can solder its perfectly doable, assuming its not an oddity
with custom pots. I once had an amp with a 4 gang volume pot with
centre taps - no chance of replacement!

Ah, ye should have defeated (removed, exorcised, castrated, mullered)
the loudness switch ...

--
Adrian C

On Sun, 30 Aug 2009 14:24:52 -0700 (PDT), NT had
this to say:

On Aug 30, 7:38*pm, jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy *them.

TIA
JimK

If you can solder its perfectly doable, assuming its not an oddity
with custom pots. I once had an amp with a 4 gang volume pot with
centre taps - no chance of replacement!

I once had a custom pot made by Morganite Resistors. It was a dual
gang semi-log and reverse semi-log with a centre click. It cost me
nothing; they were so intrigued by the order :-)

I think I might still have it somewhere - I can't remember ever
getting the correctly-shaped tuit for whatever it was I was going to
build - hell, it was about 30 odd years ago.

--
Frank Erskine

On Sun, 30 Aug 2009 11:38:27 -0700, jim wrote:
How feasible is a DIY repair?

Not too bad. A squirt of contact cleaner into them by whatever means is
worth a try. If that doesn't work, they're typically held together by
bent-over metal tabs on the bodies, and you can carefully take them apart,
clean directly, then reassemble.

If they're standard shafts, values and mountings (if direct on a PCB) or
there's room for some (screen) fly wires then you can always replace.

Even if the shafts are something oddball, you may be able to mate the
shafts from the damaged ones to a modern part.

The only time it gets really tricky is when the clearances are too tight
to get an off-the-shelf part in there (oscilloscopes are notorious for
this!) or the part's really oddball.

cheers

Jules

dave wrote:

switch cleaner. afaik WD40 is a moisture displacer.

Water dispersant, to give it its right title. Hence the WD in its name.

Dave

If you use Electrolube {obtainable from Radiospares } it will both clean and
lubricate, did the job on my Hitachi volume control

Sam
"Dave" wrote in message
...
dave wrote:

switch cleaner. afaik WD40 is a moisture displacer.

Water dispersant, to give it its right title. Hence the WD in its name.

Dave

jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy them.


It sdepends if they are on the board, or connected by wires. If the
latter its a tricvial excecrise..mut do take pictures of which wires go
where.

If the latter its a bit harder.

As clearing solder from the pins and breaking them out of the board is a
bit more skilled. If they are being replaced, cut them off and remove
the leftovers.


Replacements hafe to physically fit, be the same value, be log or linear
taper, and have the same shaft to fit the knobs (round, round-with flat,
or splined)

Apart from that, butyy moulded track if you can find them. Lats longher.

Try a spray of contact cleaner first tho. It may be just dust..

TIA
JimK

On 31 Aug, 16:19, dave wrote:
On Mon, 31 Aug 2009 09:12:29 +0100, The Natural Philosopher



wrote:
jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy them.

It sdepends if they are on the board, or connected by wires. If the
latter its a tricvial excecrise..mut do take pictures of which wires go
where.

If the latter its a bit harder.

As clearing solder from the pins and breaking them out of the board is a
bit more skilled. If they are being replaced, cut them off and remove
the leftovers.

Replacements hafe to physically fit, be the same value, be log or linear
taper, and have the same shaft to fit the knobs (round, round-with flat,
or splined)

Apart from that, butyy moulded track if you can find them. Lats longher.

Try a spray of contact cleaner first tho. It may be just dust..

TIA
JimK

I thought I was the typo King:-)
Just to add, that on my Trace amp there are some sensitive custom IC's
- be careful you know how to de-solder if the pot is soldered to the
board. Replacing one of those chips is much harder - and may be
difficult to find anyway.

ah can you refresh me on how to desolder please?
I was imagining using a desolder pump thingy I have or cutting the
legs off the old pots (a la Natural Philosopher) and then taking the
remaining "feet"? out one at a time...

JimK

In article
,
jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy them.

I'd first try using a cleaner/lubricant. This is my favourite - Maplin
may sell it too.

http://www.solotechnic.co.uk/super-1...nt-i23588.html

Just cleaning can be a short term fix but they really need a suitable
lubricant in the longer term.

It should be easy to get electrically similar replacements, but the
larger older types can be difficult to match mechanically.

Also note 'preferred' values may have changed - so you'll probably have
to use a 47kohm where the original was 50kohm, etc.

If the pots are just mounted on a panel and wired to the board, changing
to modern ones should be easy. More difficult if they're mounted on the
PCB.

If you have got to change to something different, I'd go for moulded
track ones - they last longer.

Somewhere like RS Components have a large range of generic types. But you
might find originals by Googling.

--
*I didn't fight my way to the top of the food chain to be a vegetarian.

Dave Plowman London SW
To e-mail, change noise into sound.

In message , "Dave Plowman (News)"
writes
In article
,
jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy them.

I'd first try using a cleaner/lubricant. This is my favourite - Maplin
may sell it too.

http://www.solotechnic.co.uk/super-1...nt-i23588.html

Just cleaning can be a short term fix but they really need a suitable
lubricant in the longer term.

It should be easy to get electrically similar replacements, but the
larger older types can be difficult to match mechanically.

Also note 'preferred' values may have changed - so you'll probably have
to use a 47kohm where the original was 50kohm, etc.

47k x 11 is almost 50k

--
geoff

In article ,
geoff wrote:
Also note 'preferred' values may have changed - so you'll probably have
to use a 47kohm where the original was 50kohm, etc.

47k x 11 is almost 50k

That needs explaining.

--
*If at first you do succeed, try not to look too astonished.

Dave Plowman London SW
To e-mail, change noise into sound.

In message , "Dave Plowman (News)"
writes
In article ,
geoff wrote:
Also note 'preferred' values may have changed - so you'll probably have
to use a 47kohm where the original was 50kohm, etc.

47k x 11 is almost 50k

That needs explaining.

FFS - Spinal Tapesque ...

--
geoff

"Dave Plowman (News)" wrote in message
...
In article ,
geoff wrote:
Also note 'preferred' values may have changed - so you'll probably have
to use a 47kohm where the original was 50kohm, etc.

47k x 11 is almost 50k

That needs explaining.

You will have to tell him that its ~500k he won't notice on his own.

In message , "dennis@home"
writes


"Dave Plowman (News)" wrote in message
...
In article ,
geoff wrote:
Also note 'preferred' values may have changed - so you'll probably have
to use a 47kohm where the original was 50kohm, etc.

47k x 11 is almost 50k

That needs explaining.

You will have to tell him that its ~500k he won't notice on his own.

Didn't understand it, did you dennis

clue - in Spinal Tap, the guitarist liked to turn the volume control on
his amp up to 11 (being a bit past 10, no using your fingers to work
that out

So a 50k pot is a bit past 47k (not talking physics here)


--
geoff

On Aug 30, 7:38*pm, jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy *them.


Spray with aerosol electrical contact cleaner.

Robert

In article
,
Robert Laws wrote:
On Aug 30, 7:38 pm, jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy them.


Spray with aerosol electrical contact cleaner.

Contact cleaner on its own can be a short term fix only as most pots use a
lubricant between wiper and track, and cleaner will remove that. Best to
use the stuff made for the job. Electrolube and Servisol both make it. You
might even find it in Maplin.

--
*I took an IQ test and the results were negative.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article
,
Robert Laws wrote:
On Aug 30, 7:38 pm, jim wrote:
poss OT but it's DIY :-

I have an old but nice Yamaha bass amp combo which has had scratchy
pots since I bought it years ago - they are nearly all (volume, tone
etc) scratchy to a greater or lesser extent.

How feasible is a DIY repair? I am ok with a soldering iron and would
appreciate any help/pointers as to what to look for/check when finding/
buying new pots to replace the old and from where to buy them.


Spray with aerosol electrical contact cleaner.

Contact cleaner on its own can be a short term fix only as most pots use a
lubricant between wiper and track, and cleaner will remove that. Best to
use the stuff made for the job. Electrolube and Servisol both make it. You
might even find it in Maplin.

--
*I took an IQ test and the results were negative.

Dave Plowman London SW
To e-mail, change noise into sound.

Or of course, he could try WD40 ... :-)))

Arfa