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jazz wiring nightmare

W

wolfmaster19

Sep 24, 2010
92
0
#1
hello lads,

i'm been nearing the edge of sanity for the past 3 days as what started as a simple inspection of my mia jazz..

upon opening the control plate i had noticed the pots not being grounded from one to another (unaware that that they were being grounded through the plate)

that only led to more noise being outputed.. no biggie i just had to cut the wires and all would go back to normal... which it did for a few seconds.. after which total silence followed

upon invanely striking the poles for the faintest response i had noticed the wire from the tone pot had disconnected from the output jack.. fixed it as well but still nothing just faint sounds, only on certain pot times..

i've even went so far as opening the pots to see if i had slipped some solder by mistake but they were clean...

i dont know what to try any more, the wiring is perfect and connections are solid.. but the bass has very low output..

what am i doing wrong??
 
#2
I take it you do not have an ohmmeter. If true I suggest disconnecting the pickups and connecting them one at a time straight to the output jack. You can use two jumpers with alligator clips to temporarily connect them. Let us know the results. Putting an electronic watch with a second hand near the pickup will allow you to hear it pulse the coil through a working pickup
 
#3
turns out I do but what is weirder is all the readings are correct

I've managed to get slightly more output today after the billionth resoldering but it's still unsignificant as compared to what it was before this tragedy began

I get the faintest response from hitting the pole pieces now.. which might indicate the pickups are ok.. but still the joints are solid and I am pretty confident with my solder gun

I don't think the cap on the tone pot would cut my output this much if it were to die.. if at all..

could I have damaged the pots with the heat?? is that possible?
 
#5
You may have burned up a pot. A solder gun puts out much more heat than a smaller iron, and can burn up a pot quickly. Been there, done that, put on a clean t-shirt to go get a replacement pot. Since you have an ohmmeter, check the pots as well as the pickups: 1) outside lugs should read within the manufacturing tolerance of the nominal value of the pot. Then check the wiper to each outside lug, and the value should change progressively when you rotate the shaft, zero to nominal value on one lug, and nominal value to the other. Also, sometimes a solder blob can get loose and fall into the pot, also shorting it out.

"Out of phase" will make the bass sound honky, but should not drop the overall volume that much when both pickups are full on. And even if they are out of phase, when you roll one volume knob all the way off, you should still get the same volume you used to get out of the other pickup individually, and vice versa.
 
#7
and while your at the electronics shop, buy some of these.

You may have burned up a pot. A solder gun puts out much more heat than a smaller iron, and can burn up a pot quickly
Click to expand...

Very likely, I'd say.

Clip one to the little eyelet that secures the solder lug to the resistive wafer while you are soldering. Also, don't solder to the pot casings. There's no need. All those digrams with the bent back lugs that solder to earth are not great for novice soldering. Solder a short length of wire to the lug that goes to earth on each pot, twist them together with the bridge earth, and solder this to the earth lug on the jack. Make sure you use shakeproof washers for the pots.
 
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#10
got some more readings and here are the results, tone pot reads 0.21, bridge pot .21 and neck pot .20 (all rolled off, I get same readings when boosted with the other lugs) pots are obviously 250k

overall I should only hear a 20% cut in volume but the level output is actually below that..

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edit: got a read of the pickups as well, the bridge reads 7.57k and the neck 7.07k (in the norm)

and yet it still sounds like it's outputting at 10%
 
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#11
Make sure your probes are on the solder lugs them selves, not just resting in those eyelets that connect them to the wafer. With repeated soldering there can be a lot of resistance or even an open circuit here.

Also it's important to not just test the pot wiper at the limits of its rotation, but during its rotation as well.

Even though you said it's new, I'd also test the lead. Use aligator clips to attach the probes, and wiggle the jacks around.

Also, do you have any shielded wire in the circuit or from the pickups? If so there's a chance there's a short in the central (hot) wire to earth at the braided wrap. I've been point-to-point soldering for decades, and I still use a heatsink clip on braid.
 
#12
sorry but what do you mean by open circuit?

I've forgot to mention I tested the rotation as well, it was smooth all the way up to .21

I checked the lead and it seems ok, the cavity is shielded but there is nothing to make contact with it from the main circuit, going to double check that again
 
#13
Did you measure the resistance at the output?
Plug your lead and connect your meter at the other end of the lead.
When both volumes at full you should be reading like 3.5kohm.
With only one volume at full you should be reading around that pickups resistance.

wolfmaster19 said:
I get the faintest response from hitting the pole pieces now.. which might indicate the pickups are ok..
Click to expand...
If you have a faint response this means pickups are not OK. What do you hit them with? You should be hitting them with a ferrous metal, like a screwdriver.

This will make you sure about the pickups are OK or not:
LoveThatBass said:
I suggest disconnecting the pickups and connecting them one at a time straight to the output jack. You can use two jumpers with alligator clips to temporarily connect them. Let us know the results.
Click to expand...
 
#14
yes i hit it with the screw driver tip, volume level response was same as the strings (really low)

going to check the lead through the output tonight and redo all the wiring, again

edit: btw i reveresed the wires on the bridge pu to see if they were really out of phase but it turns out i had again lost that little volume i had
 
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#15
I'm taking it to the tech, thanks anyway guys

edit: upon giving up i decided to try it one last time (on my desktop setup) and guess what, it works perfectly, volume is loud and tone is rockin!! .. gonna bring the amp to the tech instead.. thanks again chaps!
 
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