I'm feeling rather pleased with myself..

[Stoo]

I've got a little micro hi-fi system on my desk here which I use to play the audio from my PC through, but it's over 10 years old now, and the volume knob stopped working properly..

Rather than being a nice smooth scale up and down with values of 0 to 50, it turned into the equivalent of a random number generator, which is *really* handy at night when you want to turn the volume down, and it goes right up to full, wakes half the street up, and leaves my ears bleeding..

Not ideal, as you can imagine..

Now, given the state of consumer electronics these days, I had little to no hope of ever getting the thing fixed, but I thought I'd give it a go anyway, on the assumption that it was probably a dodgy potentiometer, which with any luck I could get a replacement for, getting to it would probably be another matter though.

To my surprise the JVC UX-1000 is a surprisingly well built bit of kit, with it coming apart in a PC style way - take the screws out of the back, release the side panels, undo a couple of cables and take the front off..

This all comes apart okay, and I get to the front control board, and sure enough, there's the "pot", in the middle of the board, and luckily it's not a surface mount component, so out comes the soldering iron, and various apparatus.

After I freed it from the board I hooked it up to my Dad's old analogue multimeter to check out how knackered this ALPS 740N "pot" was. As I turned the shaft of the "pot" around, the multimeter needle did the equivalent of a squirrel on speed at a rave, bouncing around all over the place.. Not good I thought..

Dad had a look too, but he had the sneaky suspicion that this wasn't actually a potentiometer, but a rotary pulsing switch.. Oh bugger I think, where the heck am I going to get a new one of those to fit?

So while I'm googling for a replacement to no avail, I undo a couple of little clips on the switch, and the whole mechanism comes apart..

Into three nice big bits, and not firing a myriad of tiny components everywhere! Result!

So I clean up the switch contacts and surfaces up with a bit of cloth, put it all back together (which was also a surprise), and tested it on the multimeter again..

Yup, it now pulses at a regular interval with a constant turn of the shaft.. Cool Beans!

I then solder it back onto the board, and reassemble the hi-fi..

No bits left over!

Plugged it in, and turned it on.. It didn't explode!

Connected it up to the PC, and behold, sound came out, and the volume worked!

Feeling quite smug, I then looked at the display.. which now resembles digital vomit, displaying random things with each button press..

Nuts!

Oh well, I'm not chancing it again, at least the volume works now

[Funkstar]

nice one!

My mum used to freak out when i started doing things like that. She is used to my dad having a go and nothing ever working again

[Zak33]

Originally Posted by Stoo

So I clean up the switch contacts and surfaces up with a bit of cloth, put it all back together (which was also a surprise), and tested it on the multimeter again..

Yup, it now pulses at a regular interval with a constant turn of the shaft.. Cool Beans!

I then solder it back onto the board, and reassemble the hi-fi..

No bits left over!

Plugged it in, and turned it on.. It didn't explode!

Connected it up to the PC, and behold, sound came out, and the volume worked!

WELL DONE...you deserve to feel smug

and you've saved the environment cos you aint gonna buy a new stereo now

[beanbandit]

Originally Posted by Stoo

No bits left over!

Now thats the impressive bit

Thats the one major problem with pots & switches, they can get clogged up with dirt and stop working correctly. Its one reason why i have a can of switch cleaning lubricant for these instances. Works wonders and saves lots of time.

Originally Posted by Zak33

and you've saved the environment cos you aint gonna buy a new stereo now

Its also saved him some pennies as well

[Stoo]

Than I had 1/2 a bottle of wine with my BBQ

[hitman67]

JVC are good systems - I have an FS-SD770R doing the exact same job here with my PC.

[tiggerai]

Stoo, do you wannna come and do mine too?

my old skool aiwa is still going strong apart from the volume control is dodgy as described!

will either go up, or down... never both ways

[acrobat]

Nice My stereo is an old CD/Radio/Tape -to- Tape deck/ all built together in a nice stereo. But its probably almost 20 years old now... and I'm such a cheapo, that everything on it is broken apart from the radio... and yet I still use it

So the cd is broken but I just use my PC. The tape to tape is broken but I don't use tapes anymore. And the speakers are broken, so I've plugged in a little pair of old PC speakers to the headphones output which works as speakers. So is basically just a big 2 foot by 2 foot radio.

[TheAnimus]

Yup it wasn't a "rotery encoder" but if it was one of these, its easy to see if its broken, as the pattern would go from high Z (impedance, ie disconnected) to low Z (ie ~0 ohms). And it would have at least 4 terminals rather than 3.

[Stoo]

Nope, three terminals, but it did it did flip from open to closed circuit as you describe when the switch shaft was rotated. Rotate it quickly and it pulses (obviously).

It certainly wasn't a potentiometer.

[TheAnimus]

hmm normally they have grey code using 2 signal lines. :S oh well

[Stoo]

I did try to google the part (ALPS 740N), but Samsung have thoughtfully named a monitor with that exact code..

Heh, found it, or at least it's distant cousin, twice removed..

http://www3.alps.co.jp/cgi-bin/WebOb...3&varietyId=12



3 signal pins, and two solder lugs to secure it to the pcb

[TheAnimus]

of course it is, i'm been retarted and thinking of the optical type (or powered).

[Stoo]

*nod*

When I had it apart, it looked a bit like this:



The rotary bit was attached to the shaft, then there was the metal contact frame, then a plastic bit to hold it all together..

I presume it just got a bit grimy after a few years and interfered with the contacts, which cocked up the decoder sequence, confusing whatever was controlling the volume

[Andy3536]

Good job, take it apart again, it's probobly just a connector knocked out for the display.

Should i also be smug doing a similar thing 5 days a week

[Clunk]

I've been trying to resist, but has anyone else noticed the vast amount of double entendres in this thread?