RESTORATION OF A 1959 BUSH TV85                                                                                                 Page 4


This red thing is the line linearity sleeve flattened out for repair. Normally, this wraps around the tube neck inside the scan coils. The sleeve contains two separate shorted turns made of foil, which are sealed within it. These have the effect of damping the line scan coils and linearising the sawtooth current going through them.

Slide the sleeve in and out and you can adjust the linearity. Well, that's the idea anyway. It's actually quite difficult to do in practice.

Damage has occurred at an edge in the past, rendering one of the coils open circuit. After some preparatory work, I repair the break with a strip of foil tape. This is then hidden behind more tape.


So what about the picture? Well here it is, along with a camera artifact that creates a white patch that isn't really there.

The set is now left switched on for several hours to 'burn it in' and hopefully the tube getter can 'get' to work soaking up those errant gas molecules. In any case, the tube is already quite good.

The tuning of the 'Bush' buttons at the front is now citically adjusted. Both BBC buttons are found to be tuned to Channel 1 and both ITA ones to Channel 9, so it looks like this was originally a set used in the London area.

The set is now working quite well, but not quite well enough yet for this particular customer, who has a penchant for brilliant 'sparkling' pictures.

After some experimenting bridging dropper sections to raise the HT, I end up placing a 1N5408 rectifier across the metal rectifier instead. This raises the HT to about 20 volts above spec. and the picture does now indeed sparkle!

This was worth doing in any case, because the metal rectifier was a little 'tired' - reducing the previous HT value below where it should have been. All the dropper sections remain in circuit. These should provide adequate switch-on surge limitation.

The lower of these two fuses feeds the high tension circuit, the higher the low tension (heater) circuit.

Now I've put a semiconductor rectifier in, the switch on surge will be somewhat higher, so the value of this fuse will have to be increased from the present 0.75 amp. I've decided to put in an anti-surge 2 amp, since one of these is to hand...

It's time to repair the damage I caused to the picture mask when originally extracting the innards from the cabinet.

First, the mask is cleaned back and front with a soft pad and a detergent solution.

Here's one of the chips being positioned onto the mask before being fixed with superglue. This works well on the plastic and gives a very strong bond, when the pieces are pressed firmly together to exclude air.

There is also some minor crazing damage to the painted surface of the mask. This means some repainting will be involved. I use a deftly applied mixture of white acrylic primer and a pale cream acrylic.


The cabinet parts are now prepared for reassembly.

Here the greasy 'grunk' is being removed from the grooves in one of the knobs with the tip of a screwdriver.

The bakelite knobs are then washed and polished.

Now to do what I can to improve the appearance of the back. The 'B' of the Bush insignia has been badly damaged.

I have a go with a silver pen...

Well, still not perfect - but a lot better...

The back is also cleaned and then treated with that 'ArmorAll' vinyl 'protectant' you may have seen here earlier.

Here's a period touch... the original dealer label. This is dry-cleaned up with a 'cheesy' rubber.

This label backs up the evidence that this was originally a 'London' set.

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