pickup testing help

[Procreatur]

my brother has a yamaha attitude custom. it carries a dimarzio woofer pickup and P type pickup and a piezo bridge. it has an active circuit. from the specs on dimarzios website, the P pickup should ohm out to around 11K. i'm only getting around 9K. the symptom is seriously decreased output from the P. it is a 4 conductor, across both coils it reads the 9K. any other way to determine whether its definitely the pickup without having a known good replacement at hand.

[tedmich]

isolate each coil and check for a signal when you tap the coil with a small screwdriver, an analog meter helps with this.

 

pickup Mfg. tolerances are notoriously loose 9k ~ 11k saves a little money on the magnet wire. I'd suspect some of the other circuit components; can you swap out (ie divide and conquer)?

[Procreatur]

it's hooked up to the preamp, of which the piezo works perfectly, so does the other pick up, so i'm kinda of leaning away from that being the issue. i reflowed the solder joints form the pickup leads. all i have is a DVM. i should have an analog and a scope, but i didn't make it to that part of my life when i was employed and not a full time student.

 

i didn't think the resulting differences in resistance would be enough to decrease the output significantly, and so far it appears i am somewhat correct. the bass/treble controls are shared between the P and woofer. i wish i had a schematic, it'd be much easier. yamaha sucks for this.

 

i did the screwdriver test with it hooked up to my computer and got noise from both sides, but wasn't sure if it was the pickup or not, and i don't have a spare laying around.

[WRGKMC]

I would need to see how the thing is wired. If the Piezo was a mod added to the guitar I would be suspicious over how its wired up. The Neck pickup may be going through the preamp. Also stock wiring on an electric 2 pickup doesnt accomidate a 3rd pickup. The preamp install may have been modified to have a blend with the humbuckers improperly. Disconnect the wires on the affected pickup and hook it directly to a guitar cord and see if the volume comes back. Try it with the other also. If it does theres something else in the circuit loading the signal down. There may be a case where someone mis matched the pickups and didnt get a matched set. The Neck pickup should be less ohms than the bridge. Maybe someone install the 2 in the wrong positions? 9K is pretty normal for a humbucker, its plenty of henries to get sound out of it. Also if its a 4 wire conductor one of the coils may be out of phase or partially shorted cutting the sound in half. Testing each coil will let you know the whole story. Humbuckers can be wired in series or parallel also doubbling or halving the impedience.