PYE LV20/B18T 1948. Heart transplant.

[rogerdup]

Hi David,
This part always look tired on sets, but they keep working for an undefined
time until they give up.
I have a lot of spare wire to rewind them anyway for who need to..
Regards,
Roger

[FERNSEH]

The circuit of the Pye B18T and LV20 line output stage.
By using the recovered energy from the scan coils the PY31 boost diode supplies an additional 40 volts negative to the cathode of the PL38 output valve. Effectively increasing the HT for the output stage.

DFWB.

[Heatercathodeshort]

Pye certainly had an odd way to list their components. C17A etc and to add confusion the printing in the manual could have been sharper. J.

[Heatercathodeshort]

I have constructed a Paxolin base plate for the LOPT and mounted it as neatly as possible in the same position as the original.

It only remains to fit a replacement frame hold slider, the original being O/C, repair the cabinet and see what can be done with the finish.

At least it now shows a reliable picture.

Regards, John.

[beery]

It looks the part now. Are you sure you fitted it? I looks like it was always there to begin with!

Cheers
Andy

[Heatercathodeshort]

I quite enjoy mucking about like this but it's a lot easier if you have all the bits, brackets, Paxolin and screws to hand to fabricate small items.

I'm fortunate in having a shed dedicated to this purpose used mostly to repair all the mechanical junk not related to the repair of vintage radio and TV.
It would be very difficult if not impossible to carry out this type of mods on a kitchen table.

It's a bit untidy but I know where everything is!

[PS Don't show these pictures to your wife or partner..]

[mark pirate]

It's a bit untidy but I know where everything is!

It is certainly tidier than my spares (junk) shed, at least you can walk in there!

It looks the part now. Are you sure you fitted it? I looks like it was always there to begin with!

You certainly have done a very neat job John, I am sure that the cabinet will turn out just as well.

Mark

[beery]

Hi John,
I see you have a metal framed bench with a wooden top which has a metalwork vice on it and the woodwork vice is mounted on a proper woodworking bench. A very nice setup.

Cheers
Andy

[FERNSEH]

HKS wrote: "I have constructed a Paxolin base plate for the LOPT and mounted it as neatly as possible in the same position as the original."

Hi John,
The application of an adaptor plate, excellent, avoids drilling holes in the chassis metalwork.

DFWB.

[Heatercathodeshort]

The chassis is now just about acceptable with the Cuckoo LOPT.
Maybe some time in the future I will have a go at winding a 'universal' transformer for this series of PYE chassis.
The year goes so fast and you can't stop it. I would like to rewind at least 5 years!

Another Forum member presented me with a pair of B18T/LV20 cabinets. Both were in fair condition but over the years had been bashed about a bit.

Now what do I do? Restore the original case or take the easy option and refinish one of the cabinets presented.

I decided to have a go at restoring the original case and learnt a bit about the early shortage of wood and materials. Wood was licensed by the post war government and austerity went on for far too long, restricting it's use in manufacturing and the supply of home market products.

The only substitute was Bakelite, used extensively from 1945 to the early 1950's. By clever design PYE managed to mass produce the B18T and include a wood cabinet into the bargain.

My Pye cabinet was a total mess. All glued joints had become unstuck, the finish was ruined by deep scratches and there were signs of very old woodworm.

First it was decided to re-glue the entire cabinet. It was rather like putting together one of those MFI kitchen cabinets kits, so popular in the 1970's.
Woodworking 'W' adhesive was used, a great product and any over spills can be removed with a damp cloth.

The old varnish was then removed with 40 grade emery cloth, finished with a fine sandpaper. The post war economies then came to light.
The top and front of the case carry a very thin veneer but the sides [and who gawps at the sides?] are just plain white ply.

The whole cabinet is then stained with the fluted vertical corner columns picked out in black. The final finish was probably a form of spray on lacquer. The overall effect is quite pleasing and so typical of 1940's design.
Very little material is wasted.

The pictures show the cabinet glued up and drying in the sun. I have attempted to save the PYE logo. The few worm holes have been injected before the whole case was treated with a suitable woodworm destroyer and preservative. The last two pictures show the cabinet stripped ready to have the odd bits of missing veneer replaced. John.

[Heatercathodeshort]

A quick update on the cabinet. The case fell to bits literally. All the glued joints and strengthening blocks were adrift.

Woodworking W adhesive did the trick as it always does and after removing what was left of the old varnish[?] with 80 grade paper a start was made on making good.

A darker stain was applied. By the look of the can it must have been as old as the chassis itself! Nice spirit stuff, unhealthy to breath apparently but it smells nice. I used a darker shade to cover up the slight colour differences of all the sections of veneer that I had to be replace especially at the bottom and edges.
This is an old trick used by the manufacturers themselves to cover up imperfections in cheap timber. I always thought it was such a waste to house television receivers in high quality timber that would be thrown on a bonfire ten years later.

It took many coats of polish before it started to build, rubbing each coat down with fine steel wool. Another five applications should do the job.

Not perfect but at least it has been saved by the skin of it's teeth. The plastic mask has been propped in place just for the picture.

I will post more pics when completed.

Regards, John.

[FERNSEH]

Hi John,
It's looking good, you've got the wood stain just right.
It'll be better than it was when it was new.

DFWB.

[mark pirate]

Looks very much as it would have done when it left the factory, even down to the vintage stain used!
I think it is a much more attractive cabinet than the later LV20.

Mark

[beery]

Hi John,
It looks great. However, I'm sure the fun police would not aprove of your use of vintage wood stain containing solvents. You need protecting from yourself, I mean, I bet you didn't even wear a hard hat whilst applying such dangerous chemicals to the cabinet!!

As a good citizen you should use lovely water based stuff which will react with the wood glue and loosen all the joints whilst making the veneers swell up, so that you have no choice but to buy a nice new flat screen TV

Cheers
Andy

[Heatercathodeshort]

Well that is it! No further improvement after another five coats.
I may take off the gloss with ultra fine wire wool and then burnish with wax polish but I feel that is really a step too far with such a rag bag chassis.

I tried to replicate a 1950's ITA advert. I think my effort was very arty but a mate suggested I should stick to the day job.

Final step is to refit the chassis and set it up. The back will have to wait.

John.

[Heatercathodeshort]

[QUOTE=beery;1047973] I'm sure the fun police would not approve of your use of vintage wood stain containing solvents. You need protecting from yourself, I mean, I bet you didn't even wear a hard hat whilst applying such dangerous chemicals to the cabinet!!QUOTE]

There is a lot behind the scenes of this thread that may not at first be realized.

I did in fact look up the details about applying the old Ronuk/Colron spirit wood dye. No information was available so I decided to overdo it a bit just in case.
The WW2 gas mask stank and the air raid wardens hat from 1941 had been designed for a much smaller head.

Well I am still alive so it must have worked but that Asbestos filter in that old gas mask may give me a problem in 30 years time.

Oh well, nothing is guaranteed. John.

[beery]

Hi John,
I see I needn't have worried as you had adaquate protection for the job.
Thanks, that made made my day

Cheers
Andy

[Heatercathodeshort]

I have all but have finished the B18T. I will burnish the cabinet when it is really hard, probably at least a couple of months.

It lacks a back but this should be easy to fabricate other than the elongated vent holes. I wonder if you can buy a 'punch' for these. It must exist.

This project was a challenge/exercise. It was never intended to be a full restoration to makers spec. As it turned out the original type LOPT, should a good one turn up, [unlikely] can be easily fitted as no circuit modifications as such have been carried out.

The cabinet if you could call it that turned out to be quite a head turner parading on the cat walk in it's new dark stain and polish.
It certainly looks a bit better than it did from the pictures at the start of this adventure.

It is very stable and gives a crisp picture all day without any EHT drop.

Just a bit of fun. Regards, John.

[rogerdup]

Very Nice! I like. good work!
I would like to share some good pictures of my Firestone 13G3, but I'm still waiting for the missing front knobs
Roger

[mark pirate]

Looks great John, I have a real soft spot for these little Pye sets, my B18T had not seen power for over 55 years, but was an easy job to restore and has a nice sharp picture. Like yours it is happy running all day without issue.

The back panel is totally flat, so should be easy to make one up, I have a few radiogram backs that make good replacements.
plastic Pudding bowls make a good replacement for the 'Bowler hat'

Mark