Bizarre pots crackling problem - now solved !

[icastle]

[quote name='discreet' timestamp='1363787467' post='2017586']
'Tis true, our guitarist had this problem and it was indeed a build-up of static from his plastic pg. He shielded the back of the pg and connected it to earth and lo, all was silent thenceforth.
[/quote]

You had him killed?

[V4lve]

Wierd. I took the shielding off the back of the guard and it seems a whole load better.

[rmorris]

[quote name='BILL POSTERS' timestamp='1363653617' post='2015468']

Matter of interest, was it a 3 ply one ? Just wondering if it had a different material in the centre.

[/quote]

I thought I had posted a reply to this but can't see it here so apologies if double posted.
Yes it's a 3 ply black/white/black plastic. I think it's only the outer face that is the issue though as the problem occured where that had worn to a shiny area.

[discreet]

[quote name='icastle' timestamp='1363792963' post='2017734']
You had him killed?
[/quote]

Er... no.

[rmorris]

[quote name='icastle' timestamp='1363712479' post='2016418']
I've heard of this but have never found myself hugely convinced.

You need the right mechanical interactions and humidity and to create and maintain a static charge on a material and I find it unlikely that many people manage to get both of these environmental anomalies on a regular basis.

Some materials are prone to static (ever been in an office where your shoes, the carpet surface and metal door handles give you a spark?) but finding the 'correct' combination of materials in a scratchplate would take an illogical degree of work.

Even if it *is* a static charge, once it's dissipated then it's not likely to reappear in a matter of seconds.

Shielding scratchplates and body cavities is more to do with eliminating RFI than controlling the build up of static.

I'm not doubting that changing your scratchplate resolved the problem you were having but I'm more inclined to think that the physical process of moving stuff about when you changed it actually rectified the original issue.

But hey, I'm no physicist so I'm quite happy to be wrong.
[/quote]

Yes the charge does dissipate quickly but the action of rubbing fingers / hand etc against the scratchplate causes further charge. It only occurs while you're playing. If you're careful not to rub the scratchplate it doesn't happen because you're simply not producing an electrostatic charge.
Additionally it occurs as a problem where the scratchplate surface has worn to a shine - near strings / around pots etc.
And many players report it becoming a problem only after several years as the scratchplate becomes more 'polished' by friction.
In general it's more noticeable if you're using high gain/distortion circuits.
It's worth bearing in mind that depending on design and impedance parameters 'normal' Hi_Z pickups can be very sensitive to all sorts of noise sources.
I once spent a good while tracking down a tick from a guitar at what seemed like 1 second intervals. I should have realised it earlier but it was my quartz battery watch with a seconds hand. You could watch the hand move and hear the tick simultaneously !

[icastle]

[quote name='rmorris' timestamp='1364217812' post='2023267']
I once spent a good while tracking down a tick from a guitar at what seemed like 1 second intervals. I should have realised it earlier but it was my quartz battery watch with a seconds hand. You could watch the hand move and hear the tick simultaneously !
[/quote]

Now that's one that I have encountered in the past.

Another one was those green LED calculators - go anywhere near an amp with one of those and all hell lets loose.

[rmorris]

[quote name='V4lve' timestamp='1363942947' post='2019756']
Wierd. I took the shielding off the back of the guard and it seems a whole load better.
[/quote]

That sounds like the shielding wasn't connected to 'Ground / 0V' or the connection wasn't 'solid' enough.
'Continuity' as tested with a meter is not always enough as the connection can have a significant inductive impedance (esp a round wire connection - flat braid is better).
And whilst Copper tape might be more fiddly to work with than the 'black conductive spray' often seen , the Copper is always better.

If the 'shielding' is 'floating' then it could make things worse by acting as a 'transmitter' for the interference.
'Floating' shields can be worse than having none at all !
I know this is a bit a bit 'hand waving' but it's not a simple area !
( if you're wondering - yes this sort of thing is part of what I do for a living :-)

[rmorris]

[quote name='icastle' timestamp='1364239305' post='2023715']
Now that's one that I have encountered in the past.

Another one was those green LED calculators - go anywhere near an amp with one of those and all hell lets loose.
[/quote]

yeah - wel just hang a guitar pickup around the front of an average PC ! The problem always used to be CRT monitors but they are rare now. Light Dimmers are another nuisance and I once tracked a periodic blip down to a DVD player a good few rooms away in a friends house ( CE regs ?)
The watch thing strikes me as a particular issue thoufgh as it's going to be on the player's wrist :-!

Getting away from the staic issue I know but it's all annoying...

[hamfist]

[quote name='rmorris' timestamp='1364217812' post='2023267']
I once spent a good while tracking down a tick from a guitar at what seemed like 1 second intervals. I should have realised it earlier but it was my quartz battery watch with a seconds hand. You could watch the hand move and hear the tick simultaneously !
[/quote]

Quality !

[BILL POSTERS]

Electricity meter in my house makes any amp within about ten feet buzz, light dimmers anywhere in the house do similar, dont forget the house wiring will act as a transmitting aerial.

In my old house BT had fitted a piece of kit that allowed more than one phone line per pair of wires coming in to the house, and that made anything at all, amps radios etc buzz, even my car radio on AM with the car parked outside.