Hofner Colorama Guitar Repair

2nd September 16.
This week I was totally blown away.
A few weeks back I was presented with a 1959 Hofner Colorama, serial number 320, with the instruction 'Just do what you can to get it playing !'.
It was absolutely covered in thick grime, the volume controls were totally seized up, the selector switches wouldn't budge and there was no output at all.
The strings apparently hadn't been changed since the 1960s. These were put on before plain 3rd strings were widely available so it had a plain B-string in its place. They were all rusty and so I couldn't even get it anywhere near in tune to try it out.
That turned out to be a blessing as it would have spoilt the great surprise I got when I completed it.

The first step, Try and get the electronics working.
I removed the control plate and sprayed the insides of the volume pots and switches with my trusty Servisol Super 10 switch cleaning lubricant.
I also noticed there was a detached wire that would need re-soldering later.
I then left it untouched for a week.
When I picked it up again one of the pots rotated, although somewhat stiffly. The other was still seized.
The switches though were now reluctantly moving.
This was encouraging and so I cleaned up all the components as best I could before spraying them again.
Then I put it aside for another week.

The next time I tried it I had both pots moving & all switches operating but none of them were as free as I would like.
So I cleaned them all out again and re-sprayed them, then spent a while continuously operating them all until eventually they all moved to my satisfaction.
Now it was time to solder the detached wire in place and check if I had an output.
For testing things like this I have a tiny battery operated amplifier which one of my friends made many years ago. It works through headphones and is ideal to use in my workshop for quick try-&-see testing.
By tapping each pick-up I could hear an output and amazingly no crackles when I turned the volume pots!

The next step was to get everything cleaned up so that I could assess what else was needed to get it playable.
The fingerboard was absolutely caked in dirt so I had to clean that off before I could properly measure the neck straightness. There is no adjustable truss-rod in this and so if it was bowed I would be in for some extra work.
I used a single sided razor blade to carefully scrape between all of the frets. I then rubbed it with Dunlop Lemoil applied with a cloth to bring it up to a clean condition.
Using a notched straight-edge I discovered that the fretboard itself was remarkably straight.
It had a tiny bit of back-bow, but as it had no strings on that was ideal at this stage.
The frets though were nowhere near level. That didn't matter as I would be levelling & dressing them later to get rid of the string wear grooves.

I removed the tuners for cleaning and lubricating. They were in reasonable state and cleaned up quite well.
A couple though had slightly bent shafts. I tentatively applied some pressure to one to see if there was any give in it and allow me to get it straightened. There wasn't and so I decided to leave them as they were. I didn't want to be in the position of breaking an original tuner.
Tuner shafts are not easy to straighten and can often break if you try - strange that they seem to bend ok when you drop them, but never want to go back.

For cleaning the body I just used a very slightly dampened cloth (with spittle which is very effective for this type of stuff, but I didn't tell the owner), and then buffed it up with a clean dry cloth.
I never risk using any modern cleaning agents on vintage instruments. It can get underneath the finish and cause it to lift.

Step 3, Sorting out the frets.
The frets were way off level and most had string wear grooves. All were very dirty and tarnished.
The height was ample to allow me to achieve a fret dress without the need for a full or partial re-fret.
There were seven high frets which I spot levelled first. Once they were the same height as all the others I performed a full fret dress, re-crown & polish to get them looking bright.

This guitar has a zero fret which the strings rest on just forward of the nut. On measurement I established that it was far too high.
To get a decent playing action and intonation at the 1st positions I prefer to have a string height at the nut (or zero fret in this case) of 0.15mm/0.006" greater than the 1st fret height. This time though I decided to go a tiny bit higher so that I would have a bit of wriggle room if I needed to do any tweaking later.
I fixed a feeler gauge of the right thickness to the fret-board adjacent to the zero fret, held in place with double sided tape so it conformed to the fret-board curve. Then with a fine file I brought the height down level with the gauge.
After removing the gauge I was able to re-crown the fret and polish it up to a smooth finish.
Lowering the zero fret meant I also had to adjust the string-nut slots a bit deeper to suit.

Step 4, The bridge & tailpiece.
The bridge on this guitar is adjustable for height using a couple of thumb screws. It is a moveable bridge that is secured to the body by string tension only.
I wanted to achieve a 12th fret action of around 2mm/2.25mm. Before I started it looked as though it was originally over 3mm. I wasn't able to measure it accurately at the time because it wasn't fully tuneable then.
I wanted to get some idea if my target was achievable. So I positioned the bridge in what would be its correct location and then rested a straight-edge from the zero fret to each of the bridge E-string grooves in turn. Measuring the 12th fret distance from the straight-edge proved that the action would be close to the 3mm that I suspected.
Adjusting the bridge thumbscrews didn't get me down enough to reach my target.
The problem was that the adjustment studs were bottoming out in their bridge holes.
Nobody was ever going to want to adjust the bridge upwards any significant distance and there was plenty of clearance under the bridge. So there was enough scope for me to safely grind a little length off the stud tops.
After that I polished up the bridge.
The trapeze tailpiece was a bit mucky and had got stuck preventing it from pivoting up/down properly. A bit of cleaning and lubrication sorted that out.

Step 5, Re-assembly and stringing up.
After refitting the tuners it was ready for stringing up.
It is quite a short scale instrument of about 618mm/24.33" without an adjustable truss-rod. In its natural state as I've already mentioned, the neck had a small back-bow. Therefore I decided that 10-gauge strings would probably be the most suitable. A smaller gauge probably wouldn't have enough tension to pull the neck into a slight relief and if I required more relief then I had the option of going up another gauge.
So I chose a set of Ernie Ball Regular Slinky (10-46 gauge) strings from my stock and began stringing up.
Having got a bit of tension an all strings, I then positioned the bridge to give a decent intonation and roughly set the height, tweaking both as I got closer to concert pitch.
Whoa! That can't be right. The tone is far too good for an old light-as-a-feather semi-solid guitar with a body made up of a plywood top and bottom sandwiched over (probably) some low cost timber.
But it's not plugged in yet so just carry on tuning up and see where it takes me.
After reaching concert pitch and allowing the strings to settle it still sounded great acoustically and the tuning was very stable.
A couple of tweaks to the bridge height and position got it to a very decent action with intonation pretty much spot on all the way up the neck.

Step 6, Plug it in and try it out.
Wow! As I stated at the beginning I am totally blown away! The sound of this thing is awesome.
This is the coolest instrument I've worked on for a long time. Not only does it look the part but the range of sounds it gives out is phenomenal. It can go from treble jangly tones to bass heavy rock sounds and everything in between. Add a bit of overdrive punch on the amp, hide behind a screen and no-one would believe what guitar you have in your hands.

Regretfully I didn't take photos at the start nor as I progressed. But here's a few of the finished article -

The technical bit - So, as far as I can tell it is a 1959 Hofner Colorama 2 in original unmodified condition.
Serial number = 320.
The scale length measures 618mm/24.33".
The fingerboard looks like rosewood with a radius of approximately 8"/200mm.
The body is semi-solid with plywood caps on the top and bottom. Finished in red with gold stripes around the edges.
Headstock has 3-a-side open geared tuners and two gold stripes on the front.
Frets are 2mm wide by 0.70mm high (0.079" by 0.028").
The neck width measures 42.84mm/1.687" at the nut and 52.00mm/2.047" at the 14th body-fret.
Neck depth measures 25.80mm/1.016" at the 1st fret and 27.20mm/1.071" at the 10th.
String spacing is 33.50mm/1.319" at the nut and 46.50mm/1.831" at the bridge.
Two enclosed single coil pick-ups with an impedance measuring approximately 6.6Kohms.
Each pick-up has an independent 250Kohms volume control pot (both marked 250K 519).
3 slide switches = one on/off for each pick-up and one for rhythm/solo selection (i.e. 70% or 100% volume).
Pick-up selections are: Bridge, Neck, or both.
Wiring is similar to the Hofner E2 circuit except for the values of 1 resistor (560K instead of 330K) and 1 capacitor (2.2nF instead of 4.7nF).
Action (after this set-up) -
12th fret: Bass-E = 2.25mm/0.089", treble-E = 2.10mm/0.083".
Zero fret = 0.99mm/0.039", 1st fret= 0.43mm/0.017", 2nd fret (capo'd @ 1st) = 0.25mm/0.010".
Neck relief at 7th fret = 0.08mm/0.003".