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
Nasty! I'll bet that made parts of your anatomy twitch :-)
Dave
I have already said its not the best thing for the job, what more do you want, blood? ;-)
Indeed, and I would not suggest it for that application either. However the one case of a wiping contact as in a pot - I have had some success with.
For something like a through hole PCB mounted pot, then you can desolder each contact with a soldering iron and desolder pump.
You will probably need to apply some fresh solder to the tip of the iron to tin it, and allow for more rapid heat transfer to the tab. Reflow the joint and then suck it clean with the pump. You may need a couple of bites at each to get rid of all the visible solder. Once all the pins are desoldered you may find they are still "stuck" by a thin film of solder. A gentle wiggle of each should free it. Sometimes a bit of lateral pressure on the end of the tab with a flat bladed screw driver will free it. (a handy knack to practice is to hold the tab away from the sides of the hole in the PCB with the tip of the desolder pump as it cools - that prevents it getting stuck back into the film of solder)
(Note that If you are dealing with very fine PCB traces, a small hole annulus, or anything surface mount, then it is probably safer for the board to run a sharp knife down the contacts and cut the device away first. Each remaining leg can then be flicked off with a hot iron with very little risk to the board).
Note that if pumpless, the outer sheath of coax if stripped makes a fine braid to attract solder onto.
HOWEVER, having worked in the game many years, the best way to strip a component KNOWN to be bad is to cut its legs of and remove them one by one with fine pliers and a soldering iron, and redrill the holes if you haven't got desoldering equipment.
It also works well for politicians, but is sadly illegal.#
OK, fair enough, but I actually posted that reply before you said that there were better products. The order that posts appear depend on how quickly they arrive at the servers.
I don't doubt it. It's just that WD40 is nasty stuff when it comes to electronic equipment, and I would rather that DIYers don't get the idea that it is ok to use it *anywhere* in such items of equipment. It's not just that there are "better" chemicals for the job. It's more a case of there being correct ones, and unsuitable ones, and WD40 is a singularly unsuitable one. It's not even a good lubricant when it comes to plastic, and many pots have plastic component parts.
Sorry to harp on about this, and it's not particularly a dig at you John. You've been more than helpful to me over the years, on questions that I have asked here. It's just that I have seen so much irrepairable damage done to equipment by people that believe WD40 to be a magic cure-all, that I always get upset when I see anyone recommending it for tasks such as this.
Arfa
yup, fair point.
Surprisingly few lubricants work well on plastic IME[1].
Tis ok, no offence taken. I had a feeling when posting the original comment it would get some reaction! ;-) However I thought it worth mentioning since I was in a situation were I was anticipating needing to replace a pot on the amp (and possibly a switch as well) and they were going to be a pig to get at. I could not find my can of switch cleaning solvent, and thought about what else is floating about. WD40 was to hand. Given it was a case of expecting to have to replace the pot anyway, there was not much to lose by trying the WD40 on it in this case. Much to my surprise it actually worked very well, and continued to do so several months later. (not tried the particular amp for six months
- so I may need to report back later if it has shagged it completely!)
I don't think of it as a magic cure all (as their sales literature would portray), but then again I find it has some uses and is not as diabolical as many make out. There are even times it lubricates long enough to be useful. However I agree with what you say - use inside electrical or electromechanical equipment in general is not a good idea.
[1] That reminds me, what is the lubricant usually used on things like scanner runners - typically plastic bearings on highly polished rails? I have a Nikon slide/film scanner that could really use relubricating since it suffers stiction problems sometimes that prevent it working correctly.
Yes, we can see that...
The point about "correct" solvents for electronics work is that they have been specifically formulated not to attack the large majority of components. That is the main reason for using those particular solvents.
There are still no guarantees, but with any other solvents you're completely on your own.
Arfa, I hesitate to ask this... but please could you be more specific about the kinds of damage that WD40 can do?
So, given that we don't know the exact ingredients, but have a rough idea
I love the stuff, use it all the time.
Tone pots don't usually see enough wear to wear out, so just cleaning will nearly always sort them out. Volume is worth trying for cleaning, but you might well need to replace them.
I'd first try using a cleaner/lubricant. This is my favourite - Maplin may sell it too.
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.
Because like all that type of stuff it does many things after a fashion, but non well. It's not a good lubricant. Not a good penetrating oil. Not a long lasting rust proofer.
Works well enough to stop a garden gate squeaking. But not for long.
Often there is no lubricant, the friction between the plastic and metal being very small.
Have you tried cleaning the slide and bearings very thoroughly? Of course, the other possibility is that enough of the plastic has worn away that you're getting the toy-woodpecker-on-a-pole effect.
I got some spray silicone lubricant in Lidl. Sort of dries so it won't come off on the finger etc or collect dust. Worked a treat on a slow electric car window by lubricating the glass channel.
Its silicone grease spray on sort.
I had this issue with a big plotter. Man came to fix, diagnosed sticky runners, and I had to tell him to remove the dried on gunk with I think acetone, and then relube with his spray silicone.
Or hard wire the lot to '11' ;-)
Yup, used IPA on a Q-tip...
There is some white (ish) grease on the runners. I doubt its down to ware since the scanner had been used very little.
I've always been told that it evaporates quickly, leaving a residue behind
- which then attracts dust and other debris, making it useless as a lubricant, and potentially worse than not having used anything at all.
It seems reasonable - but not great - as a penetrating fluid, so long as the parts are thoroughly cleaned afterwards and then treated as appropriate; other products designed to just be a penetrating fluid will likely do a much better job, ditto with rust proofers.
As Dave says, it's a quick fix - just not a long-term solution to any problem.
That's probably why it's so popular, because lots of people either use it in situations where they don't get to see the long-term problems (e.g. such as tradesfolk who come in, do a job, then leave again) - or because when the problem reoccurs they don't put it down to being a failing of WD40 (and realise that doing the job using something else would have fixed the issue for much longer).
cheers
Jules
It wrecks the frictional properties of rubber (neoprene ?) drive components such as belts, idlers, pinch rollers, clutches etc. Once it has found its way into / onto these items, there is no removing it no matter what you use. Replacement of the afflicted items is the only possible way forward. This is often either impractical or not cost effective, if the individual parts are even available. The stuff clings, and creeps by its very nature, so as fast as you think that you've cleaned it off any affected surface, ten minutes later, it's back ...
I have also seen a lot of CD and DVD mechs over the years, which have been treated to a dose of WD40 to try to cure things like trays that don't come out properly. Often, trays are designed to run 'dry' - that is with no grease - relying on the fact that the sliding and bearing surfaces are very smooth 'oily' plastic. WD40 can completely wreck this delicate situation, such that one or other side of the tray sticks, particularly if the drive scheme is asymmetric, or the whole opening / closing sequence becomes 'stuttery'. Once a tray has been affected in this way, I've never managed to totally successfully restore it. Sometimes a repolish with jeweller's rouge will get it 'good enough', and sometimes some silicone based furniture polish will help, but they are never quite the same again. And the chances are, all that was needed was a new belt, in the first place ...
Arfa
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