Ice Amplifiers

Modification of a Cheap Electric Guitar II

Outline

Into

If you have read the first part of this article you may agree that the guitar looked good when it was finished...

Problems

The guitar has been finished for about a year, and it has some problems. The most distressing is that the guitar is very noisy (it has excessive pickup from many sources (CRT's, strip lights) and is generally louder (in this respect) than any other guitar I have every heard.

The second problem is that the lacquering needed a bit longer than I gave it and the lacquer has worn off due to it being slightly 'tacky' constantly. As a result of the lacquer being worn away the gloss paint has deteriorated to very matt and has begun to crinkle (ripple across the wood surface) this is actually the lacquer that is moving but it looks black.

Solutions to the Paint Problem

The paint job could be solved in two ways. But firstly the problem is that the guy doing the painting needs to be patient... and secondly that a can finish is not as good as a gun finish. This is due to the propellant in the can being depleted as the can is emptied. This makes the finish not consistent over the area. Secondly the nozzle is quite small (in diameter) when compared with a gravity fed gun nozzle. This makes the particles of paint very fine and consequently the thickness of a layer (of paint) from a gun is considerably greater than from a can. It is necessary to use more layers from a can than a gun. An unreliable source tells me that the Fender guitar company uses 5 coats of paint (colour) and 15 coats of lacquer. I can't confirm or deny this, however I wouldn't be surprised if it were true.

Now I can't afford nor have the inclination to buy/hire a compressor, set of guns, hoses and spraying mask. And I don't know anyone that I could borrow all of the above from. So there are two options. Do nothing about the finish. Or, take the guitar body to a car spray shop and try to persuade them to do it for me. This is not as crazy as it sounds I know of a reputable company based in North West London. When visiting this company some time ago I was intrigued by the finish on a guitar and the chief guitar tech told me that he had had them done at a car spray shop...

Solutions to the Noise Problem

The noise problem is much easier to get around. The solution is to make the cavity of the body (the cut away section where the pickups and wiring go) electro-statically screened from the rest of the world.

Remove all the pickups wiring tone and volume controls etc. Glue the foil into the cutaway and onto the back of the scratch plate. It doesn't have to be neat, no one will ever see it. You can use just about any glue you like except copydex, which is what I started with... and it doesn't hold. The problem is that the aluminium and the plastic (scratch plate) are smooth (relatively) consequently the glue has very little surface area to bond with and it wont hold well. In the end I used tensol cement. This is the same stuff that you (may have) used to build model planes/cars/boats/spaceships with when you were a little younger. You may remember that if you breath it in too freely then you will get a headache... (don't forget that its quite a good solvent (especially of plastics)

Its a good solvent of plastics: it untangles the strings of hydrocarbon and when it dries they re-tangle together or something - it's often called "plastic welding". Wood glue was used on the wooden body but it didn't cut it either so I ended up using Arildyte which is a two part resin.

Once the glue has dried or gone off / cured. You can re-assemble the wiring and scratch plate arrangement. The foil on the scratch plate and in the guitar don't have to be in electrical contact. Nor do either have to be grounded but in this case both those things happened (the body of the volume pot is normally grounded and that is attached to the scratch plate... which presses against the foil of the body).

This shielding is effective only on 'stray' fields. If you are using a computer to get music tabulature, and you sit in front of your monitor (CRT only) you will still get noise. This is not avoidable because you want to have the string interacting with the field generated by the magnet in your pickup.

Pictures follow for illustration only, they are not necessarily 'best practice'

The Body The Scratch Plate The Scratch Plate