Sadowsky preamp low output

[gimmeagig]

I have two basses with a Sadowsky preamp in it.One has the DiMarzio Ultra Jazz and the other has Nordies NJ5FS pickups.
The pickups are set with a similar distance to the strings,same gauge strings, but one of the basses is much louder with the preamp on. With it off there's almost no difference.The Batteries are fresh.
The controls work as they should ....vol,blend tone, it's all like it should be, but there is a very significant difference in output.
I'm not an electronics expert and my repair guy who installed them can follow the installation instructions but I don't think he knows much beyond that.
Is there some way of wiring the Sadowsky preamp differently that will affect only the output but not the functions? Some wire that he might have gotten mixed up?
I have a multi meter and I'm wondering if there is a way for me to measure the output of the two basses, so that I have real numbers for comparison?

 

[Jerry Ziarko]

Honestly, it sounds like either the pre is bad, or it's not working properly because of how it is wired. You have the perfect scenario though. Take off both back control covers and follow each wire path, color by color on both basses to see if they match. After you're done there, get back with your findings.
P.S. go here for how things should be wired: [Invalid or Expired Link Removed]

 

[gimmeagig]

Hey thanks Jerry. I printed out the schematic and tomorrow I'll try to figure out what is going on.

 

[narud]

i recently had a sad pre that the active setting was lower in volume than the passive setting and had a faint distorted sound on the decay of the notes. luckily the previous owner took it back