Triaging/fixing guitar problems

[Nathan of Brainfertilizer Fame]

Okay, I have the Ohm Meter.

Here are the problems some of my guitars have:

1) guitar cuts out if input jack is moved at all

2) guitar cuts out if volume (or tone) knob gets moved at all

3) No sound when blade switch is in position 5 (neck only humbucker), but seems to have normal sound in notch position 4 (middle single coil + neck auto-cut to single coil) because there is a different than sound in position 3 (middle single coil only)

4) 1% of sound in any position (can only hear sound coming through amp if I turn it up to 9 or higher on 75W amp)

5) no sound at all in any position

So do I just start re-soldering joints? Is there an easy way to figure out which joint it might be? is there an easy way to figure out if a pot has gone bad (if that is even possible)? is there an easy way to figure out if a pickup has gone bad (if that is even possible)? is there an easy way to figure out if a section of wire is bad (if that is even possible)?

I think that an input jack problem can sometimes be dirty contact points. Could it also be the arm portion of the jack is too loose, and so bending it back in a little might help?

I need a triage system, step by step, to help me figure out where the problems are so I don't waste time fixing things that aren't broken.

Is there a guitar repair book anyone can recommend?

[dragan]

I'm no expert but I'd start by replacing the jack &/or looking for a wire(s) shorting to ground.

[tbonesullivan]

first make a physical inspection of the solder joints. Look for any loose wires, cracks in solder joints, and so forth. Look for any sharp bends in wiring that could result in a break of the conductors.

Also clean all pots with tuner control cleaner/lubricant, and clean all jacks and switches with electrical contact cleaner. make sure that the switches have no mechanical defects.

[Toadroller]

Send them to me, they sound like junk.

Failing that, diagnosing a problem is a process of elimination through good information and some intuition/ experience. As you probably know, your ohm-meter is going to be a continuity tester, telling you if a wire is good between point A and point B.

Do a search for wiring diagrams for the given guitar setup you have, e.g. HSS wiring diagram will get you something like this from Seymour Duncan or Stewmac.

Then compare it to the guitar in front of you and start figuring out how it works. Annotate the diagram with what you find in your guitar you start to pull things apart. A few good pictures of the guts can be a life-saver if you forget which post the green wire came from.

Figuring out wiring takes a bit of patience and thinking, but is good practice. My first car was a Rabbit GTI with a windshield that constantly leaked into the fuse and relay box, destroying relays and shorting fuses. Using a Haynes wiring diagram that was mostly accurate, I was able to keep it running, scavenging relays from every junkyard I came across. What a wonderful POS that car was. It surely helped me figure out that setting up a guitar is a piece of cake compared to some German idea of efficient wiring.