At this point, I’d done enough reading and looking at things to feel decently confident to go forward. I must admit that I took these crappy pictures partly to have something to refer to if I screwed something up and had to go back, but luckily I got through it okay.
I’ll start this post with a little info about the output jack. The standard output jack of a guitar is a mono 1/4 inch Tip-Sleeve (TS) female jack. The guitar cable has a TS male plug, where the signal travels on the Tip conductor, and the ground sits on the Sleeve conductor. The amplifier provides the ultimate ground reference for the guitar via the sleeve conductor of the cable. All the electronics in the guitar are grounded to the same reference provided by the amp. That said, the EMG pickups actually require a 9V battery, which they apparently don’t want to “ground” to the guitar’s signal ground. For this reason, the EMG pickups require a stereo Tip-Ring-Sleeve jack so that you can separate the signal and power grounds. Here’s the diagram from the instructions:
As you can see, the battery’s (-) post goes to the ring connector of the jack. This was kind of strange to me, I couldn’t completely understand why you couldn’t just ground the battery with the other signal ground, which brought me to the next question: how exactly does the battery get grounded? If you use a stereo TRS cable with the TRS jack, the ring serves as the battery ground and the sleeve is the signal ground, but when you plug the cable into the amp, does the amp’s jack have separate contacts for the ring and sleeve? I didn’t think so – my amp only has one speaker, so I couldn’t see why it would have a stereo input jack. If the amp had a mono jack (no contact for the ring of the plug), how does the battery get grounded, or does the battery voltage just float with no real ground? After I got the guitar all put together with EMGs, I discovered the answer. I tried using a stereo TRS cable to plug the guitar into the amp, because I thought there might be some reason to separate the grounds, but I found that this did not produce anything but noise from the guitar. I then tried plugging a mono TS cable into the stereo guitar jack/mono amp jack and the guitar worked perfectly… With this setup, the ring and sleeve connectors on the guitar jack are effectively grounded together on the sleeve of the cable, so I’m not sure why they separate the battery and signal grounds on the output jack. Maybe the idea is to push the ground connection as far away from the electronics as possible, I’m not sure. Anyway, this debacle actually gave me a good idea of something to try – an external power source for the pickups, which would mean you’d never have to replace the battery. I haven’t tried my idea yet, but I’ll write a post later.
Here’s a picture of the old mono jack, pulled out from the guitar:
After trying to figure all that out, I finally started to de-solder all the controls. Here’s a picture about halfway through the process of removing things:
One thing worth mentioning is the removal of the knobs from the controls. The knobs on this guitar were stuck on the pots pretty well, I couldn’t seem to pull them off without making my fingers bleed. I read a tip on the internet that said you can easily remove the knobs if you wrap an old t-shirt around the knob, and then pull up to get the knob off. I tried that, and it worked pretty well.
I finally got all the old crap taken out, here’s a pic:
Here’s a pic of the empty control cavity, the only things left are the toggle switch cable and the string ground wire.
That’s enough for this post, more to come.