The guitar project that went wrong … then wronger

Back in the 90s when the distinction between music store and pawn shop was rather blurry, I acquired a second-hand silver sparkle Les Paul guitar that only said “Lady Luck” on the headstock and “Made in Korea” on the back of the neck.

This was a time when cheap guitars were really bad. Everyone and their brother had a beginner-level Squier or Jasmine that wouldn’t stay in tune and had the tone of a brick.

Lady Luck played well, but she had an extremely bass-heavy tone. It just never sounded good. Sometime in the early 2000s I actually tried to revive her by transplanting some nice Seymour Duncan pickups, but she still only sounded marginally better.

The silver guitar just hung on the wall for the past 15 years.

Since I’m now working from my home office at least eight hours a day, I’ve been trying to clear the clutter and make it a more pleasant, usable environment. That meant some of the guitars, amplifiers and camera gear had to go. I decided to clean up Lady Luck and put her up for sale.

I opened the back panel and squirted a little bit of contact cleaner into the crackling volume pots. The knobs got stiff. Then they froze. Then they unfroze … completely … and just kept spinning.

In the past few months I’ve cleaned the pots on an amplifier, a vintage clock radio, and another guitar. This has never happened before. I also couldn’t believe the same thing happened on both volume pots. I guess the corrosion was the only thing holding them together.

I had just rendered the guitar unplayable. Selling it was no longer an option.

The “hand wired” tone craze started a few years ago when Gibson started using pots connected to printed circuit boards in their guitars. That was actually good news for me because there were dozens upon dozens of pre-assembled pre-wired pots available to replace those PCBs that ranged from $30 with some questionable looking hardware up to $250 with vintage bumblebee capacitors.

Since Lady Luck isn’t a real Les Paul, I was worried the pot spacing wouldn’t quite be the same. I was wary of buying a pre-assembled kit. I decided to spend $50 and order an unassembled kit from Amplified Parts that included everything from the input plug to the switch. It also came with some really nice shielded wiring.

I immediately ran into a few issues. The pots and the output jack had larger diameters than the original hardware. I wasn’t excited about drilling out the holes and risking a chip in the paint, but I decided it was worth the risk.

Then I had to address the fact that the new knobs were also longer than the old knobs. I made a run to True Value for 3/8″ spacers. Unfortunately, they were out of 3/8″, so I had to pay double and buy a set of both 1/4″ and 1/8″. I ended up $20 into the project just for spacers!

The new selector switch was more of an issue. It was taller than the original switch, and it needed to be countersunk to reach through the body. Lady Luck is mostly plywood with an unknown top. The switch area was not that thick to begin with.

I finally decided that countersinking the new switch to make it fit wasn’t worth the risk of having the new switch rip through the front of the guitar. I had already replaced the switch in the 90s because the original had been snapped off when I bought it. It was clean and seemed fine. I mean, after all, a switch is a switch.

The instructions that came with the MOD kit were very clear, so it only took about an hour to put everything together. Of course, I still somehow managed to hook up the switch backwards. There were no strings on the guitar, so all I could do was plug it in and tap the pickups to see which one was active with each switch position.

I thought, it’s fine, I’ll just rotate the switch 180-degrees and let the wires wrap around. Wrong.

Assuming all was well, I got to the business of reassembling the other pieces of the guitar with the new stainless steel screws I’d picked up while I was True Value. I also decided to put the chrome pickup covers that originally came on the guitar onto the Seymour Duncan pickups. That entailed a little double-sided tape and some solder on the back, but it seemed easy enough.

The next morning I spent quite some time adjusting the truss rod, setting the bridge height, and adjusting the intonation to get the action just right. Then, the moment finally came. I plugged her in.

A very loud hum came through the amplifier.

I strummed a chord.

Nothing.

When I touched my fingers various places the hum would change tone or sometimes stop completely, but never did a single note come through the amplifier.

Did I wire something wrong? Is one of the new pieces bad? Did I ruin the pickups by putting covers on them?

This project had gone wrong when I destroyed the original volume pots. Now I was an additional $70 and 5+ hours into the project, and I had NOTHING.

I hung the guitar on the wall and walked away.

The next morning I got out the multimeter and started checking continuity. This was my first time using shielded cable with a metal sleeve. My first discovery was that I hadn’t peeled the shielding back far enough on the wire going to input jack, and it was touching the base of the prong, causing a short.

My next realization was that by spinning the selector switch 180 and letting the wires wrap around it, they were shorting to the sides of the selector switch.

I remedied this situation by rotating the switch back the correct direction and adding a little bit of electrical tape for insulation — just in case.

At this point, I was still getting a terrible hum, but I was also getting intermittent sound depending on what I touched.

I decided to yank the pots and see if I could get anything to work outside the guitar. Unfortunately during this maneuver I lost one of the $3 spacers into the body of the guitar forever.

After a few solder repairs, which included hooking the switch leads up correctly, I suddenly had sound. That was amazing news since it meant I didn’t destroy the expensive pickups when I put the covers on them.

I made another run to True Value to get another 1/8″ spacer.

I put everything back into the guitar.

The hum was back, and the sound was gone again.

The shielded cables were just touching too many things inside the guitar.

If I ever do this again, I will purchase shrink wrap or some sort of plastic sleeve to put over the metal braid. I didn’t have either of those things, so I started wrapping it in electrical tape. A few minutes later, the hum was completely gone, and the guitar was singing.

So after more than 20 years, this guitar finally plays the way it should. Now I can’t decide if I still want to sell it or if I should hold onto it a little longer.

And for any tech geeks out there who might be wondering, Lady Luck has a Seymour Duncan Pearly Gates in the bridge and a Seymour Duncan SH4 in the neck. 220k-ohm resistors tie into 470pF ceramic capacitors on the 500k-ohm volume pots, and .022mf 600v MOD capacitors run between the volume and tone pots.

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