How to check if Vol pot is Log or linear when the pot is in the guitar

kipple

Is it possible to use a multimeter to check if a volume pot is Log or linear wile the Pot is in the circuit in a guitar. 
Will the pot still give the same readings if it is in the guitar ?
I know how to check a pot while it's not in the guitar but I do not know if it will read the same when it's in the guitar

ICBM

No, it won't - because the pickup is in parallel with the top end of the track. But it is possible to measure it if you do a bit of simple maths.

If you meter from the pot output to ground, as you turn the pot up from zero to full, the resistance will rise from 0 ohms to a peak in the middle, then fall back to the DC resistance of the pickup. The peak will be a quarter of the pot resistance. (Technically, a quarter of the pot resistance plus the pickup resistance, but that's almost negligible by comparison.)

Where the peak occurs on the pot turn will tell you if it's Linear (at 5) or Log (around 7-8), if numbered.

Obviously make sure only one pickup is selected, if it's a guitar with more than one volume control.

kipple

ICBM said:

No, it won't - because the pickup is in parallel with the top end of the track. But it is possible to measure it if you do a bit of simple maths.

If you meter from the pot output to ground, as you turn the pot up from zero to full, the resistance will rise from 0 ohms to a peak in the middle, then fall back to the DC resistance of the pickup. The peak will be a quarter of the pot resistance. (Technically, a quarter of the pot resistance plus the pickup resistance, but that's almost negligible by comparison.)

Where the peak occurs on the pot turn will tell you if it's Linear (at 5) or Log (around 7-8), if numbered.

Obviously make sure only one pickup is selected, if it's a guitar with more than one volume control.

Thanks I will try that out. 
I fitted a new pot and pickup and it's not behaving as I thought it should and I cannot figure out what's up with it. The pot acts like an on off switch. It occurred to me I may of used a linear pot instead of Log

Funkfingers

1 Meg pots are pretty much on/off regardless of whether they are log or linear taper.

On a right-handed guitar, reversed log taper pots would seem pretty all or nothing.