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 Post subject: Variable resistor question
PostPosted: Aug Fri 09, 2019 2:45 pm 
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Location: Warner Robins, GA
I have an amp which uses several variable resistors that are panel mount which also have a couple tabs that secure the pot to the PC board so that the board is held in place by the pots.

One broke because I got the nut too tight.

Didn't see any sort of part number on the pot nor is a schematic available.

I figured on using a regular panel mount pot and locating it elsewhere, but I cannot find much in the way of 22K pots that are panel mount at least not any with a 1/4" shaft and I tried to look for one that looks similar to the original, but could not find it on Mouser's website.

The measured resistance is 22K and I don't know the tolerance.

The only numbers on the back are A2 and 03

So does that mean audio taper 20K?

If so then the pot is either 10% tolerance and right ont he edge of its tolerance or the pot is 20% and is halfway to being at its tolerance.


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 Post subject: Re: Variable resistor question
PostPosted: Aug Fri 09, 2019 6:19 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Minneapolis, MN USA
Many new pots have a 6mm shaft which will work in place of 1/4 inch.
If you post a pic we could try to look for similar mechanical construction.


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 Post subject: Re: Variable resistor question
PostPosted: Aug Fri 09, 2019 6:21 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
Does the amp work with that pot? If so get a 22k. But do you know the taper? That matters sometimes

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 Post subject: Re: Variable resistor question
PostPosted: Aug Fri 09, 2019 6:39 pm 
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Location: Warner Robins, GA
The existing pot still works and is audio taper. It is just broke where the threaded panel mount part is held to the body of the pot.

Now I'm thinking it is actually A203 which would be audio taper 20K.

I did find one 20K audio taper pots that looks like it has the same PC board mounting only it has a 6mm D shaft.


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 Post subject: Re: Variable resistor question
PostPosted: Aug Fri 09, 2019 10:12 pm 
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Joined: Jan Tue 16, 2007 7:02 am
Posts: 3241
Location: Lexington, KY USA
JB Weld?

If you can figure out the manufacturer, (... and vintage. 1949 parts were different from 2019 parts.) you might buy one with the correct bushing then make one good one out of two.

Ted


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 Post subject: Re: Variable resistor question
PostPosted: Aug Fri 09, 2019 10:19 pm 
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Joined: Sep Tue 30, 2014 6:08 am
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Location: Norfolk, VA
Tube Radio wrote:
I have an amp .....


Brand, model? I've got several hundred pots salvaged over a 30 year period from my Dad's shop, but would need a make and model to search.

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"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


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 Post subject: Re: Variable resistor question
PostPosted: Aug Sat 10, 2019 1:11 am 
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Location: Warner Robins, GA
It's a Dayton Audio PMA-250 full range plate amp.

My guess is given the lack of information on the pot itself it might be a Chinese one unless it is actually a bourns and just doesn't have anything other than the numbers I posted on it.

Oh I'm sure the manufacturer has the info on the pot, but from what I understand they don't like releasing that sort of information as they would prefer users don't fix their products themselves.

Now the bass pot is almost failing the same way so when I replace the level pots I'll look at it and see if I can find replacements.


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 Post subject: Re: Variable resistor question
PostPosted: Aug Sat 10, 2019 4:04 am 
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Joined: Sep Tue 30, 2014 6:08 am
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Location: Norfolk, VA
New, current production unit - what is the problem with getting replacement parts?

http://www.daytonaudio.com/index.php/support/

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"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


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 Post subject: Re: Variable resistor question
PostPosted: Aug Sat 10, 2019 4:28 am 
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Location: Warner Robins, GA
Didn't think they would sell replacement parts like that given they do not give out their service info.


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 Post subject: Re: Variable resistor question
PostPosted: Aug Sat 10, 2019 4:47 am 
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Joined: Sep Tue 30, 2014 6:08 am
Posts: 4862
Location: Norfolk, VA
Tube Radio wrote:
Didn't think they would sell replacement parts like that given they do not give out their service info.


Have you asked? I got some free Altec Lansing screws one time - just by asking their service support hotline. They knew of the problem I was having (screws shipped were either just right or too short - my complaint was too short. Red label UPS arrived two days later with my free screws - I needed 4, they sent 25...

Reputations are built by customer service. Drop keywords like "I've got this running and photos of the install ready for my blog, but have a problem with XXXXX...."

If they refuse to help, let them know you'll share that info with the forum members. :wink:

Just be careful if they want to send it COD via UPS....although I'm not sure if that is doable these days. Dad once had a problem with one of his Weller stations, under warranty. They were slick - we'll send you out the replacement part, and when you return the broken part, we'll credit you the amount for the part. Okay, even-Steven so far, but they stuck him with two-way shipping - more than the parts cost. Some warranty..... :evil:

EDIT: You do know that Dayton Audio is Parts Express' pro-line, wholly owned by PE........

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"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


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 Post subject: Re: Variable resistor question
PostPosted: Aug Sat 10, 2019 4:54 am 
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Posts: 20389
Location: Warner Robins, GA
Knew parts express sold their stuff.

Didn't know they owned them.


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