Potentiometer problem can you help

[6B4G]

I've got a stereo 100k 2watt log taper pot with switch and one of the pots has gone open circuit
I've tried to open it but I just can't, anyhow I've been searching the net and the only thing I can
find is 2X100k 2watt linear taper with no switch. The switch I can live without but the log I don't know.
It's from the vol control of the dreaded Leak preamp, can anyone direct me to where I can get one?

[DeathRex]

Does it really need to be 2 watts? That's a hard part to find with a log taper. Do you have a schematic showing the part?

[Geek]

Digikey part# KKA1041S28-ND

They are what I use to replace unobtanium ALPS Black Beauty.

[6B4G]

Does it really need to be 2 watts? That's a hard part to find with a log taper. Do you have a schematic showing the part?

First of all thank you guys for the reply.
I don't know why but that's the one they are using. Here is the schematics.

[6B4G]

pot is located at the right side of the schematic

[6B4G]

[quoteDigikey part# KKA1041S28-ND

They are what I use to replace unobtanium ALPS Black Beauty.][/quote]

Great, I would of got a similar one from http://www.hificollective.co.uk/potenti ... tereo.html but they are out of stock.
Thanks for that.

[DeathRex]

Don't know why it's a 2 watt, log pots usually are about 1/8 watt or 1/4 watt. With 10 volts across it, it will only be doing 0.001 watt.

[Geek]

Noise considerations - a 2W resistor has less than a 1 watt, which has less than a 1/2 watt, etc. Same is true for pots (I've measured this).

Too bad 100K WW is impractical (wire size and inductance), as that would be the nicest option. Old broadcast gear used 600 ohm pots and step down/step up transformers.

[bone]

Using a 2w pot in this circuit is just Leak being over cautious. A standard 100K log will work fine.

[6B4G]

I was wondering why anyone would do that but they would of had a reason as you say.
Spending 60+ Euros inc freight and tax for a pot seems a bit much but there are others
that spend even much more.
You would think you would need a workshop of sound testing equipment embedded in your
head to be able to tell the difference but perfection is an art.
Oh well unfortunately most of us have more sense than dollars.

[johnf]

If you can live without the switch on the pot and therefore have a switch on the power amp, any pot will do. I have a Noble pot which was replaced in a preamp with a Black Beauty that I found in a surplus store. The Noble channel balance is not that accurate (for an expensive pot). Each step of the Alps is dead on. So keep your cash and use something standard. You could pick up another preamp for the prices of some of them. You might see if Classique Sounds has a spare original since they gut them out to make passives.
Have a look at this thread. It has some useful background on Leak and BBC etc.
http://forums.stevehoffman.tv/threads/m ... in.271728/

[6B4G]

Thanks John but after a week of emails with Digi-Key and two phone calls due to there stupid online ordering system
I eventually received confirmation that the pot is on its why, I have dealt with Mouser in the past for parts and from the time
of ordering to the time of receiving (from Texas US to Athens Greece) max 4 days. Unfortunately they didn't have this particular pot.
Re the Black Beauty I couldn't find there ratting.

[johnf]

Maybe a bit late but this place seems to have 100k log with dp switch ( tandem rotary carbon resistors section) NOS. Actually looks like he has loads of NOS parts for any one looking to refurb stuff.
http://www.partridgeelectronics.co.uk/17Cresistors.htm

[Geek]

Keep in mind that ALPS doesn't make the Black Beauty anymore. Most all you see on the net are fakes.
(even reputable dealers are getting hit with fakes from their suppliers)

They do make the Blue Velvet, though.

[6B4G]

I eventually received the Digikey part# KKA1041S28-ND due to the customs being absolutely @#$%&* (to keep it clean) a 30 euro part ended costing 145 euro, but at least the pot
works great. Another thing is that I don't think I will ever deal with DigiKey again as there online ordering system is stupid, there was a 6 day tennis game with emails, I have purchased
from MOUSER many times and never had a hick-up, from the time of ordering to receiving the items 3 days and that is from Texas US to Athens Greece.
This has been my two cents of complaints LOL.
Anyway, thank you guys for all your help.