Page Three


At this point the four-way mains cable to the on/off switch is replaced. The yellow-clad screened sound volume control wiring is in shocking condition and awaits attention.


The new on-off and sound volume wiring has now been fitted. The black cable carrying the mains is now screened for still better hum supression. The length of this cabling is generous, since it will have to reach further than before in the Baird console cabinet.


Time now to get 'down and dirty' as I unscrew the component board fastenings to have a peep underneath.

I particularly want to see if there are any components, normally invisible, hidden underneath the boards.


The real problem turns out to be perished hidden rubber wiring. This could be carrying dangerous voltages.

This is a good reason, in my opinion, why it's always better to do a thorough job, rather than simply replace the components necessary to get the set to 'work' - as some advocate.

The brown 'gunk' from long-smoking power resistors is unsightly too, and I'll try to clean it off.


It turns out the wiring is only perished near the heat-producing power resistors. It would be a right royal pain to un-loom and replace all the wiring, so I simply link in new rubber wires of the same colour, where necessary.


Here's the underneath of the main chassis re-capped. This is not a rare or valuable set so the new capacitors are not hidden inside the old.


A new width control - a power potentiometer - is fitted.

The wirewound track on the original one had come adrift.

This control mainly works by varying a shunt across the line deflector coils. The new pot is 50K, replacing a 30K. This will be OK. The nett effect will be to give this control a little more travel.


Finally the resistors are checked. It's normally the higher value ones that go 'high'.

A bit of 'highness' is normal though. This 2.2 megohm resistor reads about 3 megohms. I check the schematic to see what it does... it feeds the tube first anode so should not be too critical.


The valves are now all tested and the good ones cleaned up. Only two of them need replacing: one of the EF80 valves from the IF strip and the PL83 sound output.

I'll get the chassis working in standard trim for now, but later on the PL83 sound valve may become superfluous. I expect to be adding a separate valve amplifier unit for higher quality sound.


The line output transformer assembly clips back in and the three valves behind it are plugged in... from left to right these are: the PY82 HT rectifier, the PL81 line output, and the PY81 boost rectifier.

The PL81 displays the usual brown marks inside the glass but actually tested fine. I take the view that a 'burned in' but proven valve like this is likely going to be even more reliable than a new replacement.

The (horizontal) EY51 EHT rectifier has been changed previously.


The LOPT assembly shielding panel is now secured with its one screw and fibre washer. This is situated a little close to the PY82 HT recifier in my opinion - hidden here behind the panel on the far left.

You may be able to see that I've painted the internal surface matt black, to absorb the heat from this valve, rather than throw it back by reflection.


The tube and its ancillary parts are mounted up. Next, I mustn't forget to plug in the scan coils.

The ion trap magnet is cleaned and placed at the end of the tube neck in a 'guestimate' position. The pointer on it (not visible here) points toward the screen. This is the other way round from how it was originally!


Same old problem though... how to safely secure the front of the tube! This cable tie arrangement will have to do for now.

Just holding the tube by its neck clamp - as per the design - will be insufficient when I start upending the chassis during final fault finding.

This unpleasant feature clearly shows that the TV24 variant was an afterthought; an attempt to adapt the short 9-inch TV22 chassis for a 12-inch tube.


The next morning I've made up a couple of temporary brackets to secure the tube and mask at the front.

These will be removed just before the chassis goes into its new cabinet.


Right, now to switch on!

Before doing this, past experience has taught me a quick check of the wirewound pot tracks is a good idea. Breaks in these often cause the first faults to be found.

I run around them with the Avo... This is actually the Brightness pot. When taking this photo I thought it was the Frame Hold! You live and learn...




You see, to start with the tube seemed to be cut off and I could only get a raster by placing an Avo prod on the tube cathode. Strange...