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Help How To Test Pup Circuit


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I know, I should have done a search, but I did'nt. So with that out of the way, I have wired my PUPs according to the sheet I got in the box, Texas Specials from Fender. I set up a test with three strings, just for testing, what I got was no sound except for a hummm. So I know enough to say, something was grounding out the circuit, yes? I ran a wire from the trem claw as instructed direct to the output plug with the wires from the PUP assy. I have since removed all the guts and will try again. This time I want to know if it works before I install it in my guitar, a Stratocaster '67 beater I'm refurbing as a Relic. I am also using a five way switch, Schaller. So here are some questions 1, on the Schaller the leads are numbered 1-7 with and extra terminal connected to a nut on the side of it, what is that for? 2, is there a reliable way of soldering the capacitor and ground wires to the back of the pot, I think these may be cold joint?. I will this time switch to a standard bridge no trem. I don't use it anyway. So how can I test this circuit with a Volt Ohm meter. :D

Edited by stringkilla
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It sounds like your hot wire isn't actually connected to the output jack. Are you sure that the signal is making it from your pickups, thru the PUP selector switch and then to the output jack?

A simple continuity checker is invaluable for troubleshooting like this. :D

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Trem or not bridge...you still need that ground wire.

Soldering to the back of a pot can often be difficult. One thing to do is to file the pot where you want to solder to as it usually has a coating on it that prevents the solder sticking. Also, use solder with a flux core to get more flow and maybe heat up the pot with the iron a little and get the solder to stick nicely before making a connection to this solder pad.

It could be the hot or the signal ground that has failed to reach or been shorted out somewhere along the way to the output jack as paul suggests. Testing the hot and ground of the output jack with an ohm meter may give you some idea. If a pickup is connected, the output should read about that of the pickup or pickups selected. You can test the pickups by measuring the resistance of the coil with the ohm meter set to a scale of about 10K plus to get an idea of what to expect. The volume and tone pots can also add resistance when turned.

To aid in the work, often it is better to disconnect (or leave out) the tone controls as these and the selector switch are often the source of a wiring problem. Wire them in when the basic selctor and volume and jack seems to be ok.

If the scratchplate is off the guitar, then you can still test for a signal into an amp by tapping the pickup poles with a screwdriver...if they are shorted or not connected properly, there will be no or little sound...


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A cold solder joint is also another possibilty. Whenever your guitar is plugged into an amp and it sounds like when you plug a cord into an amp and touch the other end of the cord and get that humming/buzzing noise, it's usually due to an open circuit in your guitar somewhere.

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