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Main => Everything Else => Topic started by: protokatie on December 12, 2009, 02:27:37 am

Title: What's better than POT?
Post by: protokatie on December 12, 2009, 02:27:37 am
Ok, got your attention, so get your head out of the bong:

I have an answering machine that has its volume potentiometer pretty much a burned out old hippy. It is hard to get it to stay at a volume level, esp one that is audible. I was thinking that since I only need the thing to be loud, that I could short across the the contacts, but this brought me to an obvious question: What is the minimum Ohms of this POT?

I have never actually tested a POT with an Ohm meter, so I have no idea what the low end is (IE is it .001 Ohm, or .1 Ohm, etc?). Besides, I have no way to test this particular one, as it is way too messed up to do the job, it just sits there and does whatever it wants to.

What I do know is that this POT is rated for 9V-12V DC... And well, thats about it.

Any general rules of thumb for what the low end of resistance is on these small POTs? Should I just go with a .5 Ohm or 1 Ohm resistor? Or would a direct wire be safe (in that case I would just duct tape some wire to each terminal on the pot).

After I get my answer, you may commence with the jokes...
Title: Re: What's better than POT?
Post by: danny_galaga on December 12, 2009, 03:06:07 am

Hmmm, don't most pots start at zero ohms? and then its 0-100, or 0- 10k etc...

I would be inclined to try a few resistors if you are going to dispense with the pot. Try a 100 ohm and see how loud that is. Then a 10 ohm etc...
Title: Re: What's better than POT?
Post by: Cakemeister on December 12, 2009, 09:43:11 am
What Danny said. You might let out the magic smoke if you just jumper the thing.
Title: Re: What's better than POT?
Post by: protokatie on December 12, 2009, 09:17:22 pm
Hmm, OK, thats what I was leaning towards. I guess I will pick up an assorted pack of resistors the next time I am at radio shack.. Thanx
Title: Re: What's better than POT?
Post by: Ed_McCarron on December 13, 2009, 11:50:18 am
If its a 3 terminal pot, you MAY be able to read its total resistance - if only the wiper is munged, measure resistance across the outer two terminals.  You may get a reading.

Be sure to replace it with an audio taper (logarithmic) pot.
Title: Re: What's better than POT?
Post by: DaOld Man on December 13, 2009, 03:07:03 pm
Have you tried spraying some electronic cleaner spray in it? (Check Radio Shack, they used to carry it.)
Title: Re: What's better than POT?
Post by: protokatie on December 13, 2009, 11:08:32 pm
Have you tried spraying some electronic cleaner spray in it? (Check Radio Shack, they used to carry it.)

Do you mean like canned air? Or is this something different. I have canned air, just havent tried it
Title: Re: What's better than POT?
Post by: crashwg on December 13, 2009, 11:26:56 pm
http://www.radioshack.com/product/index.jsp?productId=2102649 (http://www.radioshack.com/product/index.jsp?productId=2102649)

Or this one which looks a little more specifically made for what you need
http://www.radioshack.com/product/index.jsp?productId=2103700 (http://www.radioshack.com/product/index.jsp?productId=2103700)
Title: Re: What's better than POT?
Post by: shmokes on December 13, 2009, 11:46:35 pm
Are you a cavewoman?  Why do you still have an answering machine?   ;D

Get Google Voice.
Title: Re: What's better than POT?
Post by: protokatie on December 13, 2009, 11:55:26 pm
Are you a cavewoman?  Why do you still have an answering machine?   ;D

Get Google Voice.

Its actually my VOIP line, and since there are three of us here, and the answering machine has 4 mailboxes, it works out well. :P

BTW Magic Jack seems to work very well for me, although I had my doubts reading the complaints on various sites.



@crashwg, I will try the canned air first, then try something like what you linked. If it doesnt work, then it is resistor testing land.
Title: Re: What's better than POT?
Post by: danny_galaga on December 14, 2009, 03:08:26 am

I forgot to ask if you have actually eyeballed the pot yet? Many of them have values written on the case, even if it's in a mysterious short hand. Find that though and you should be able to work out what it used to be...
Title: Re: What's better than POT?
Post by: protokatie on December 14, 2009, 04:48:48 am

I forgot to ask if you have actually eyeballed the pot yet? Many of them have values written on the case, even if it's in a mysterious short hand. Find that though and you should be able to work out what it used to be...

Haven't taken the thing apart yet. If I can avoid that, then I will be happy. Regardless, if I take the thing apart and kill it, there is an ancient AT&T model 500 in the garage I can use :D
Title: Re: What's better than POT?
Post by: DaOld Man on December 14, 2009, 07:00:00 am
http://www.radioshack.com/product/index.jsp?productId=2102649 (http://www.radioshack.com/product/index.jsp?productId=2102649)

Or this one which looks a little more specifically made for what you need
http://www.radioshack.com/product/index.jsp?productId=2103700 (http://www.radioshack.com/product/index.jsp?productId=2103700)

What he said.

Canned air probably wont work, you need a spray with a cleaning fluid in it, to flush out the tiny traces of carbon that are stuck to the pot's wiper and to the carbon trace. Just stick the tube up to an opening in the pot (usually around one of the trace terminals), and soak it good. The trick is to get the spray inside the pot.
After that, use the spray to clean up any junk that comes out of the pot so it doesnt short anything on the board.
Dont take the pot apart, you would be better off just going to walmart and buying a new answer machine, even though those are junk.
If you really want to use fixed resistors, I would just turn the pot all the way up, whichever ever side the pot turns towards, just solder the center connection to that outside one. The pot is probably still just fine as a fixed resistor.

PS: Dont forget to turn the voulume knob back and forth while you are spraying. This will help the spary to flush out any particles that may be between the wiper and the carbon trace.
Title: Re: What's better than POT?
Post by: shardian on December 14, 2009, 08:53:39 am
I have used the electronics spray back in the day to fix the volume knob on the radio in my first car. It worked like a charm.
Title: Re: What's better than POT?
Post by: ChadTower on December 14, 2009, 09:30:52 am

I use that pot cleaner on a lot of devices.  Works great most of the time.  Occasionally the pot will fall apart but that's one that you weren't going to save with cleaner anyway.
Title: Re: What's better than POT?
Post by: Ed_McCarron on December 14, 2009, 06:47:11 pm
Contact cleaner.  The only way to fix your ancient Atari 2600 paddles.
Title: Re: What's better than POT?
Post by: ChadTower on December 14, 2009, 08:27:18 pm
Contact cleaner.  The only way to fix your ancient Atari 2600 paddles.

(http://thepopeofpentecost.files.wordpress.com/2009/03/truth_000.jpg)
Title: Re: What's better than POT?
Post by: jamesjones626 on December 16, 2009, 11:58:11 pm
damn i thought this thread was gonna be bout some purple or skunk or something...........i lost the game on this one