Guild F-30 work, Studer B67 recap: Part VI

Yesterday I started with the F-30. It needs a new nut, which is why I started the work on it that led to it falling and cracking.

The previous nut had a shim glued to it, and that’s a real pet peeve of mine. If the slot is too deep, then that happened because someone put glue at the bottom of the nut, so when it was taken off last, it pulled some wood with it. Then someone leveled the slot and as a result the slot became deeper. The quick solution is to shim the nut, which is usually done with whatever piece of wood is at hand. The appropriate solution (in my opinion) is to restore the original depth of the nut slot. So this whole preamble is to say that the slot is too deep on the F-30 and I was going to put a shim there to bring it to its original depth. The original depth is so that the bottom of the slot (which is the neck’s mahogany), is at the same height as the bottom of the fretboard.

I’ve cut some mahogany shim blanks before because I needed one for my S-300. Thinning these are always a problem. It’s not easy to rub them on sandpaper and get them flat – the fingers put an even pressure so they get all lumpy. But I figured out a way! I’ve already fitted a nut blank to the slot – just the thickness and flatness of its bottom. I stuck 320 grit sandpaper to its flat bottom, laid the mahogany strip on top of sandpaper that is on top of a granite blank, and sanded away. This way the mahogany was held in place by the sandpaper on the bottom, and it helps that the bottom sandpaper is coarser grit. I also used the bone blank + sandpaper combo to flatten the slot before gluing the shim.

I glued the shim with hot hide glue and clamped it down with a piece of acrylic that’s cut to the slot’s length. To keep the shim flush with the fingerboard, I used my rule to push it against it. However, I used it this way:

IMG_20151024_170114

So only the center was flush. I realized that after I started clamping and quickly took the clamp and caul off, put more glue on there, and pushed the bass side of the shim against the fretboard. To avoid this problem I should have used the ruler this way:

IMG_20151024_170126

Or better yet, use something like an old debit card so my fingers don’t get in the way of clamping. Should be done with this guitar very soon. I’m very excited.

While that was drying I started recapping the Capstan Speed Control board. First cap out was C17, a 220uf 3V tantalum. I tested it for continuity and it wasn’t shorted! I didn’t have the right tantalum on hand (I thought I ordered one), so I replaced it with an electrolytic. I wrote before about how electrolytics seem to be a better alternative to tantalums now, but since my electronics knowledge isn’t 100% (far from it), I’m not sure it’s fine for all applications. I definitely don’t want to throw in the wrong capacitor in a circuit that is “time-sensitive” like the Capstan Speed Control. Anyway, it’s a Panasonic FM series cap that has a 56 mOhm impedance, so it should be fine. I hope.

Next I pulled C20, a 100uF electrolytic. That’s the cap that sits between the -12V rail and the 0V rail, and it was short! Problem (most likely) solved!

Then my wife came home and we had to go to dinner, so I had to stop.

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