Tuesday, December 20, 2011

Hofner Colorama II restoration project (part 12) - repairing the metal tremolo cover

In between coats of paint, I worked on fixing the metal tremolo cover.

As you can see above, it's being held down by a washer, since it is in fact cracked completely across, as seen here:

In fact, if you look closely at the first photo, you will see that a lot of the surface chrome close to that area has cracked too and is only held in place by magic or something.

Anyway, firstly I bent and hammered it down to something resembling flat:

Then I roughed the surface of it near the crack with a view to trying to solder it together. Remember that the chrome plating in this area was close to flaking off anyway. I figured this was also the least intrusive way to join it without discolouring the surrounding chrome too much.

However, I could not get the solder to stick to the metal cover, so tried a different route.

First of all, I set about cutting a piece of aluminium into the shape of a somewhat oblong washer.

Just as I was almost finished, I discovered I had a much thinner piece of aluminium I could use, so I started cutting that out:

And here it is all cut out and polished up.

However, even the thinner piece looked out of place (don't believe how nice it looks in the photo) and I just wasn't happy with it.

I decided to just try gluing something onto the back of the cover to keep it structurally sound, but found that I couldn't get anything to stick to the chrome plating, even after heavily scratching the surface (going through to the brass in some places) and using Arardite Rapid Steel Epoxy (which is the closest thing to JB Weld I can find over here). So I figured this thing was getting so screwed up already that I would file a big chunk of the chrome plating completely off the back and try gluing again. Once I saw the bare brass, I thought I would try just one more time to solder it. This time, though, I spread quite a bit of flux over it too. I heated up a test area, and lo and behold, the solder took to it.

So I flipped it over, filed off some of the chrome and soldered the top. It's a really obvious repair, but I don't care. I'm very happy with it. I may try to polish it up a bit more, but apart from that, I'm calling it done.

Thursday, December 15, 2011

Hofner Colorama II restoration project (part 11) - flattening the warped plastic pickguard and tremolo cover

Among the many smaller jobs that have to be done to this vintage Hofner Colorama II is to flatten the warped plastic pickguard and rear tremolo cover. Here’s how they both looked before starting:


Rear tremolo cover:

I decided to tackle the rear tremolo cover first, since it appeared to be a much simpler job and also easier to replace should things go horribly wrong. I really couldn’t find any information about this on the Internet, so I did what seemed logical in my head, which was to sandwich the plastic in-between two panes of tempered glass, clamp the whole lot together, and heat it with a very hot hairdryer.

Here’s the setup:

After 10 or 15 minutes of heating the area above AND BELOW the cover, I took the top pane of glass off to confirm that the plastic had become soft, then clamped everything back in place and left it to cool naturally. Since I wasn’t in a hurry, I left it for 24 hours, although I’m sure that wasn’t necessary at all.

The tremolo cover came out completely flat. You can see a corner lifting slightly in this photo, but it’s really nothing and will easily be held flat once it is screwed to the back of the guitar body.

Next up was the pickguard. Not only was there some warping raising it up off the guitar body, there was also some bulging around the edges of the pickups, due to the pickups themselves bulging (as discussed here: http://diystrat.blogspot.com/2011/12/hofner-colorama-ii-restoration-project_12.html). Even with the pickups removed, the plastic edges wouldn’t return to shape, so this would need to be dealt with too.

I tried the same trick as with the tremolo cover, but unfortunately the pickguard material is about twice as thick as the tremolo cover, and has a much larger surface area. Even after 20 minutes or so, I just couldn’t heat it up enough through the glass to make it soft. I didn’t want to apply the heat directly in case the surface of the plastic started to blister or something else equally damaging.

It was recommended that I try pouring boiling water over the plastic, so I tried this method next. Before clamping it in-between the panes of glass and leaving it to cool down, I quickly used a flat-edged tool to push the edges around the pickup holes more or less back into shape.

This method proved completely successful, but at a cost. The pickguard was now perfectly flat, but had discoloured horribly, as shown here:

An internet search brought up a suggestion in a car restoration forum to rub peanut oil into the surface to restore the black sheen, but this method proved useless.

Next option was to try black shoe polish, but surprisingly this didn’t make any difference at all either.

So, I decided to get a bit more aggressive and removed some of the surface with some steel wool. Success! At least I knew now that the discoloration was only on the surface and could be skimmed off.

The steel wool wasn’t really aggressive enough for most of the pickguard, so I sanded it with 400 grit sandpaper (having tried 2000 grit and 1200 grit first without success):

This method worked great, but of course we were now left with quite a rough surface, shown here:

The surface was then sanded with finer sandpaper in a more random direction to remove the lines from the 400 grit sandpaper, leaving us with a nice and flat, but somewhat dull, surface:

Finally, rubbing compound was used to shine up the surface.

You can see the difference already here:

And finally, here’s the end result.

Monday, December 12, 2011

Hofner Colorama II restoration project (part 10) - repairing the electronics

Just like everything else on this vintage Hofner Colorama II, the electronics have been treated badly and need some attention. By “badly” I mean that they have been left in a damp or wet environment and the pots are scratchy or cut out completely. The output jack also needs to make better contact.

This can hopefully all be fixed with the help of some electrical contact cleaner, but first I’m going to remove all the parts from the pickguard. This isn’t strictly necessary, but since I’m restoring the whole guitar, and the pickguard also needs attention, this is the route I’m going to take.

Firstly, here’s the whole pickguard/electronics assembly. As mentioned in another post, the beauty of the Colorama is how the entire electronics circuit is attached to the pickguard and can be lifted out in one go:

Here's how it looks from behind:

The knobs are removed, revealing some rather disturbing evidence of damp. Check out that rust!

Rather that turn the whole pot by accident when I’m unscrewing the rusted nuts, I (carefully) grip the underside with some mole grips (vise-grips) and unscrew the nut with a socket wrench:

Once all four pots, the output jack and the pickups (these just push through without any screws to unscrew) are detached, some electrical contact cleaner is squirted into the gaps in the pots. I then move the pot shaft around (like turning the volume up and down repeatedly) a few times to help move the contact cleaner around. I also give the output jack a bit of a clean with the same cleaner:

Incidentally, vintage Hofners are quite hard to date, since the serial numbers are, well, a bit of a mess. You can often date them, however, by their pots. This one, for example, is stamped 250 372. "250" stands for the pot value (250K Ohms) and the "372" stands for the 37th week of 1962 (37=37th week, 2=1962). Remember that this is the date that the pots were made, so it may be a few months before they appear on a guitar. This particular Hofner Colorama II is most likely a 1963 model, so the pot codes would tend to verify this:

The Pickups are also in need of attention. The covers are bulging and the solder holding them to the bases has cracked.

Additionally, one of the pickups has a nasty dent on the top:

And the same pickup is missing one of the tabs that holds it under the pickguard:

The only thing holding the pickups together (apart from the solder) is the pole piece screws. Once removed, the pickup opens easily:

As you can see, these are single coil pickups. Hofner did make humbucking pickups in the same format, but these have “Super” written on the top, just under the diamond logo. I’m not aware of these ever appearing on Coloramas, however.

Here I'm using a small hammer to flatten out the dent on the top of the bridge pickup:

I don't want to go overboard here and I'm happy enough to stop at this point. I'm sure this will polish up nicely:

Both of the pickups were opened, the covers bent back to a non-bulging shape and soldered back on. Additionally, the bridge pickup had a new tab soldered on:

All of the nuts, washers, pointers, etc., were also cleaned with a wire brush:

A lot of elbow grease was required here, especially on the pointers, which all had very deep rust (uncleaned example shown here).

Before putting the electronics back on the pickguard (which, incidentally has been flattened and cleaned up, the details of which will be documented in a future blog post), I've put some metallic tape on the pickguard in order to reduce unwanted electrical interference/noise.

And here's everything back in place:

And the front:

Finally we add the replacement knobs (all sourced from 60s Hofners):

Monday, December 5, 2011

Hofner Colorama II restoration project (part 9) - fixing up the tremolo unit

The tremolo arm on our vintage Hofner Colorama II is supposed to be held on with a type of thumb wheel screw, but that’s obviously been lost at some stage and the remaining stud/screw had been hammered down to act like a rivet and hold the tremolo arm on, irreversibly damaging it (the stud) in the process:

The tremolo unit has already been removed from the guitar, but can be disassembled further by removing the big screw holding the arm lever on:

Here's what we're left with:

I've previously drilled into the stud to remove the arm, and the remaining stud has to be unscrewed as it is completely destroyed. That can be forced out with a pair of mole grips (vise-grips), by turning it in an anti-clockwise (counter clockwise) direction:

There's quite a bit of rust on both this part and the tremolo unit itself, so a wire brush is used to remove it:

I'm also rounding the front end of the lever, since it was originally square in shape and was catching on and damaging the tremolo cover.

A look through the parts drawer gives us some components that might be good enough to make a new arm mount. It won’t be completely the same as the original, but it should be close enough:

Here they are put together to check on compatibility and fit:

And here's the whole tremolo unit put back together with its new thumb wheel, allowing us to remove the tremolo arm any time we wish: