100k alphas gone bad with a "lump" in the value ?

[MartyMart]

Just had the third one from 5 pots go bad !
There is a "jump" if you like at about one third of the pots travel, smooth before and after.
The first bad one looked a bit wrong "mechanicly" inside, and was making the wiper lug move slightly !!  Bummer !!
It was causing lots of "crackle" and total volume loss . . . .
Anyone had that problem ?
One off, or time for more expensive pots  ??

Marty.

[Paul Perry (Frostwave)]

I've never had that problem but, I can see why it could happen, I bet these are log (audio taper volume) pots, which are made from two bits of track of different resistance compounds.
Looks like something went wrong on the manufacturing.
Tell the place you bought them from (they will want to know! before they sell more!)
I don't think it means alpha are crap, it is a temporary glitch for sure.

[Paul Marossy]

I have never had a bad Alpha pot, and I have used quite a few now - probably about a hundred of them. You must have gotten a bad batch...

[R.G.]

Me too. Never got a bad one.

[MartyMart]

Thank you Gentlemen !
I will inform ESR components about them, perhaps I'll get some replacements.
Just checked numbers 4/5 and they seem good !
Unlucky this time I guess  :cry:
Any recommendations for a slightly "up-market"  Pot ??

Marty.

[gez]

Any recommendations for a slightly "up-market"  Pot ??

I've had one or two Alphas (PCB ones) that have knackered up after a few turns.  They end up swizzling around (don't stop) and there seems to be a portion of the travel where they 'stick'.  Only ever happened with a couple though (out of many).

I use Omeg pots from Rapid now.  Far better, they're sealed, very quiet and have a real pro feel to them (feels like you're turning the knob on a hi-fi).  

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=&STK_PROD_CODE=M28683&XPAGENO=1

The pins are quite strong and can be bent to support the weight of a PCB (no more standoffs/wires).

[Ge_Whiz]

Like gez, I tend to use those green Omegs now - very quiet with the conducting plastic track.

I had two Alphas fail for no reason upon soldering just after Christmas - both okay before soldering, one dead immediately afterwards, another died a few turns later. Post-mortem revealed nothing, just a failure to contact between wiper and track. Soldering iron okay, I didn't cook them.

[Paul Perry (Frostwave)]

That is interesting, that both the reports of faulty alpha pots are from the UK. I hope nobody is faking them! I have a batch of sub-standard Alps clones (not branded Alps, though.) Bodgie pots is the last thing we need.. :cry:

[gez]

That is interesting, that both the reports of faulty alpha pots are from the UK. I hope nobody is faking them!

Doubt it.  Mine came from Maplin and ESR, both reliable sources so they're almost certainly the real deal.  The ones I've had a problem with are the 16mm PCB mount jobbies, and only them.  

I'm a fully paid up convert to Omeg these days mind  

PS  It's probably something to do with our climate...buggers up everything else in this country!  :roll:

[MartyMart]

That is interesting, that both the reports of faulty alpha pots are from the UK. I hope nobody is faking them!

Doubt it.  Mine came from Maplin and ESR, both reliable sources so they're almost certainly the real deal.  The ones I've had a problem with are the 16mm PCB mount jobbies, and only them.

Thats the ones !! 16mm PCB type.....OK, I'll go with Omeg then  
There dual concentric pots may just fit in a Boss TR-2 . . . . . .


Marty.

[gez]

OK, I'll go with Omeg then  
There dual concentric pots may just fit in a Boss TR-2

The pictures of the Omeg pots are a little deceptive in that they're quite large beasts (compared with the 16mm Alphas).  

Thought it best to warn you.  Excellent pots though!

PS  ESR sell some Omeg pots.  Just the dual-gang ones if I recall.  Between the two companies you can get the whole range...