Identification for onboard switch needed (Receiver Pioneer A-331)

No. Single turn pots (good ones) clean themselves as they are used. If they have sat up for a while they obviously did not clean themselves while on the shelf. I don't remember ever seeing a pot that flat "wore out".

If I returned a boutique amp to a customer and it smelled like WD-40 I would likely not see that person (or any of his friends) ever again. WD-40 is something mechanics use. DeOxIt is something e-techs use.

"dave= total d*****ad "

** You need to get some smarter customers.

And there is no need for the amp to smell.

** And many, many others too. ** Only the gullible fuckwits like you.

And only in the USA.

... Phil

"dave= d*****ad " <

** Dave is clearly NOT an audio tech.

Worn out pots are common sights and noisy pots cleaning themselves is NONSENSE.

Fuck off fool.

... Phil

Try taking apart the pots in a joystick. They get far more use than any front panel control pot. I've seen them with grooves worn into the carbon that match the individual fingers of the slider. I've also seen the same thing in volume control knobs on 2way radios that require turning the volume control to power on/off the radio. If you leave such a worn grooved pot in place for a long time, the lubricating grease will "migrate" into the grooves. When that happens, the individual fingers will float on top of the grease, and not make contact with the carbon, resulting in an intermittent. With flat carbon, the fingers will push the grease out of the way. With a grove in the carbon, the fingers will push the grease into the grooves.

This also has caused me some grief in the distant past, where I would "lube" a pot to break loose the shaft, and get the radio back with an intermittent volume control a few months later. However, all this is for high use 2way radio controls. I doubt that any hi-fi or even commodity radio control would see sufficient use (or abuse) to put grooves in the carbon.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

"Jeff Liebermann"

** I service mostly " pro audio " which includes mixing desks and the special mixers used by DJs.

DJ mixers have a "cross-fader " that allows a pair of stereo channels to be mixed in any proportion. Most DJs work the ring of the things - so much so that it is standard practise make the cross-fader a "user replaceable" module fitted on sub panel that slots into the main panel.

Nothing unusual to see cross-faders ( and channel faders) with all the tips worn off the fingers and deep grooves in the carbon track - right down to the phenolic backing.

Most control pots these days have the carbon track deposited on the backing material rather the old method of using a solid, moulded track and attaching it to a backing.

Deposited tracks are very much thinner and wear out much sooner.

... Phil

Phil Allison har bragt dette til os:

Are anyone using an optical fader, where moving the fader allows more or less light to a sensor, controlling the fading?

Or should I file a patent claim? :-)

--
Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske  
beslutning at undlade det.

"Leif Neland"

** I built such a set up for a customer in the mid 1980s.

Worked like a charm.

A few high end DJ desks have optical or VCA x-faders.

.... Phil

>

I've installed 2 ways, never had to fix one. Same for mechanical joysticks. I repair amps, mixers, speakers; I am thinking of adding

1970s stereos, because I love the technology. I used to be in broadcasting and can service any kind of transmitter.

Hall-effect feels left out now.

That's a bald faced lie, and you know it. Otherwise, no TV tuner would have ever needed cleaning. Bird Watt meters would never give false readings, and no one would have ever needed to polish their silverware. Silver plated RF connectors would never overheat. It's too bad that you are never man enough to admit what a useless fool you really are.

--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.

I don't know how you'd define an oxide, but I'd say that losing electrons qualifies.

** Silver does not form an oxide under any normal condition.

If forms a sulphide layer (Ag2S ) due to air containing some H2S from burning fossil fuels etc.

... Phil

I have in my mind, a tv tuner on the WD-40 can. Am I right ?

My preferred general purpose spray is CRC 2-26 . I know that says, improves electrical properties, and plastic safe.

I used to have a lot of problems with volume controls in the desert. Sand? Also have a can of Blue Shower, with the dohickies in it. I never much used it. I bought one of the last cans.

Greg

The really cool thing about CRC 2-26 . If you just gently push the button, it foams out of the nozzle, filling voids very well.

I've used most everything. Used more WD-40 over the years than anything. I also have used Cramolin Contaclean. It has made pots so sticky, they will not turn. You got to flush that stuff off, like it says on the can, after cleaning cycle.

Greg

"gregz"

** No.

On a can of Servisol maybe....

** Same as WD-40 then.

... Phil

Yep. Even worse, the silver sulfide to silver junction makes a tolerable diode (band gap = 1 eV). I was having serious problems at a radio site with what is now known as PIM (passive intermodulation). I had stupidly cleaned the silver plated plugs, but not the jacks. After a week of bad guesses, I cleaned both connectors, and the problems went away.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I had a Bird Wattmeter on the bench at one job. (QA on the PRC77) The thing read about 30% difference from one direction to the other because it was silver to silver in one direction, and silver to crap the other. The Cal lab threw a real hissy fit when they heard that I cleaned it with a piece of paper.

--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.

About 20 years ago, I was involved in a wattmeter calibration party. Mostly, we were trying to product frequency versus indicated power graphs. Should be simple enough. Right.

Because of erratic readings, it was decided that everything needed to have the contacts cleaned and tarnish removed. Someone dug out some silver polish, which made the slugs and couplers look nice and shiny, but also coated them with a layer of wax. The readings stabilized only after everything was wiped with alcohol patches to remove the wax.

After that, we found that many of the slugs produced seriously inaccurate readings. Dig out the Model 43 data sheet and it says

+/- 5% accuracy. Ok, 5% of what? Calling Bird support determined that it was 5% of full scale. Therefore, if I use a 100 watt slug to measure a 25 watt transmitter, and 5% of 100 watts = 5 watts, 25 watts indicated could be anywhere between 20 and 30 watts. So, we ran the graphs mostly at full scale with a few spot checks 1/2 and 1/4th of full scale. A Telewave 44A (no slugs required) turned out to be quite good (specified accuracy +/- 6% of FS) above about 200 Mhz, but required using the included calibration chart for lower frequencies. Also, my collection of battered Radio Shack VHF/UHF VSWR meters were amazingly accurate (in the ham bands).

There was some discussion that a light bulb dummy load and light meter was more accurate, but we didn't have time to verify the claim.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558