Low volume

Paul DiMaggio · From: Fort Nelson, British Columbia, Canada

I have a steel that has low volume, cranked right up on the guitar and half volume on a micro cube,it is drowned out by an acoustic guitar. My other steels and my strat have twice the volume at the same settings. I'm not sure when it happened. I noticed it at an open mike session I went to.
So I took the cover off and tested the pot and on the outside tabs it read almost 0 [ohms] on the middle and the left tabs from fully closed to fully open the needle went from full to the right [closed] to almost 0 as I opened it then to about 1/3 on the dial when it was fully opened. I had a spare pot and tested it it read 250k on the outside tabs and went 0 to full right on the dial on the middle and left tabs when the shaft was turned and back to 0 when shaft was turned the other way. I installed the new pot, put on a couple of strings, tried it again, same thing 1/2 the volume of the other guitars. I tested the pot in the guitar and the outside tabs read 250k but the middle and left tabs read the same as the old pot did full to the right on the dial and almost to 0 the back up to 1/3 on the dial when full open. What am I doing wrong?

Stephen Cowell · From: Round Rock, Texas, USA

Ohm your pickup... normally you can do this by turning up your volume and ohming the tip-sleeve on a cord plugged in. You should see something like 8-20K... as you turn down the volume, you should see the ohms go up to 250K. (edit: wrong, it should go to zero, it's shorting the output)

You may have a bad pickup. Please let us know the model of pickup/guitar... we can suggest normal values, or other troubleshooting steps.
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Paul DiMaggio · From: Fort Nelson, British Columbia, Canada

Ok, I was reading the meter wrong,I think. With the volume turn right down the meter reads 0 [testing on the cord]. As the volume is turned up it goes to 250k but in the last 1/4 of the turn it drops to 500. The pickup is a True-tone it is in a Melbert s8.

Jeff Scott Brown · From: O'Fallon Missouri, USA

Paul DiMaggio · From: Fort Nelson, British Columbia, Canada

I don't know. There is a running gag in my family about my carpentry skills,"As a carpenter I'm a pretty good cowboy". Well I guess at electronics I'm a really good cowboy. Smile

I checked my other guitars and they all read similarly at the cord. I truly know nothing about this stuff.

Stephen Cowell · From: Round Rock, Texas, USA

Good job on the measurements... sounds like your pickup is shorted... what's happening:

1. pot at zero... ohms zero, due to pot
2. pot in middle... 125K to each side... ohms high
3. pot at top... straight to pickup... ohms low

At max volume, you should read your pickup's resistance (well over 10Kohms) in parallel with your pot (250K), which is essentially the same as your pickup's resistance (the pot doesn't change it hardly at all).

So you might be able to examine the pickup and remove a short between the wires... but 500ohms is about right for a shorted pickup, the wire gets shorted to a pole piece (or something). You'll have to dig in further... you might be able to remove the ground to the pole-pieces and get the signal back... if you touch a pole-piece, it'll hum like the dickens though.... might hum anyway.

edit: you can also try reversing the pickup leads, you might get most of the signal back that way.
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Paul DiMaggio · From: Fort Nelson, British Columbia, Canada

So you are saying I should try moving the wire from the pickup to the right hand tab of the pot from the middle one and the wire from the jack to the middle tab? I'm not sure that I want to take the pickup apart
if the above does not work. Although I guess it ain't working properly now so how much damage can I do. I'll check it out when I get back home. Thanks very much for your help Stephen and Merry Christmas to you and yours.

Lane Gray · From: Topeka, KS

I wouldn't feel like taking it apart either.
If Mr Cowell says it has a short, I'll take his word, remove the pickup and send it to Jerry Wallace for rewinding.
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Stephen Cowell · From: Round Rock, Texas, USA

Paul... yes, I think... Unhook the wires for the pickup, then ohm between them, then between each and the p/u ground... this should let you know whether it need a rewind. If you can see over 5K ohms anywhere then there's hope, otherwise send in for the rewind.
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Bill Bassett · From: Papamoa New Zealand

You are from BC. You forgot to convert to metric..problem solved.

Paul DiMaggio · From: Fort Nelson, British Columbia, Canada

Ok, so this is what I did, I emailed Bob Allen and asked about the ohm reading of just over 6000 on the pickup. While waiting for an answer I thought maybe if I hooked the pickup direct to the jack it might tell me something. Well, presto changeo, volume! Bob confirmed that the reading was correct for this pickup.
From that I figured that the pot was to blame. I tried to solder the pot back in, unfortunately, my lack of the correct solder, heat sinks and skill fried the pot. I was south on other business and bought 3 new pots. I installed one according to the wiring diagram I have ; pickup and tone pot to the right hand terminal and jack to the centre. Fired it up, had volume but no control over it. Tested the pot and the left tab and centre gave me readings as the stem was turned. I soldered it that way and now the volume pot works but it turns counter clockwise 0 to 10. I tested the other 2 pots and one was the same but the other worked clockwise. What would a counter clockwise pot be used for?

Stephen Cowell · From: Round Rock, Texas, USA

You have to swap the outside terminals... you've wired it backwards.

And there should be a ground connection opposite the pickup/tone pot connection... the middle (wiper) connection is choosing voltage from different points in the pot resistor track. Full up is wiper shorted to pickup/tone pot... full down is wiper shorted to ground.
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