Pye LV20 lives again!

[Ricardo]

My first vintage television restoration is nearing completion. Electrically at least.

Here are some photos of the set as acquired.



The set had been stored in wet conditions and the cabinet in particular has suffered quite a bit of damage.

After cleaning away all the spider webs and other muck the electrical checks began.

Since this was my first TV restoration I proceeded with a fair degree of caution. The capacitor across the mains was removed. The heater chain proved to be intact including the Brimistor. I replaced the Hunts capacitors from various points in the heater chain to the chassis. The main filter capacitors reformed OK. I then disconnected the HT supplies to the rest of the set at the filter capacitor and gradually applied power. With full mains voltage all was well with both the valve heater circuit and the HT voltage.

At this stage I split the incoming mains so that I could apply 240V ac directly to the valve heaters via the mains dropper and Brimistor and an adjustable supply from a variac via the mains rectifier to the rest of the set. This allowed me to increase the supply to the set over a period of time whilst watching out for signs of distress. Nothing untoward happened and I was rewarded with some line whistle, but nothing on the screen and no sound.

According to my High Voltage probe I only appeared to have around 600V of EHT. So I spent quite some time checking around the line output transformer, EHT rectifier, etc. Nothing appeared to be wrong. Eventually I realised that the ratio of my high voltage probe was 1000:1 and not 100:1 as I thought. So in fact I had around 6kV of EHT. Doh!

Still no screen illumination however.

At this stage I checked and replaced various leaky capacitors and a number of high value resistors.

Eventually I managed to get first light on the screen albeit very dim.

Most of the remaining problems were down to the slider controls at the rear. Several of which were totally seized up. I removed the panel with these sliders on completely, then spent some time freeing them up and cleaning the wipers so that they gave smooth adjustment from end to end.

With an input signal from an Aurora standards converter and some adjustment of these controls I now have the following picture.



It still needs some further work, but I am very pleased with the results so far.

Richard

[McMurdo]

very encouraging, look forward to the finished set

[Boom]

Lovely work Richard. REAL tellies these are!

One day I will be brave enough to strip the sliders on my B18 for a clean up. How difficult was it?

[audiomagpie]

Good results so far Richard! I've got one of these (BV- the midlands version) in my 'round tuit' pile. The slider panel is missing (removed by the previous dabbler) so I'll replace with rotary pots and make up a little panel that fits. All this before I even think about getting 'first light', it's a winters evening job.

I do like these very late 40's/early 50's single channel sets, the are about as straight forward as TV gets (which means I'm in with a chance) and the EHT will do no more harm than make you swear, maybe frighten the cat!

Greg

[mark pirate]

Nice work, I really like these old pye sets, I recently restored an LV51F.
The chassis looks to have survived well, how bad is the cabinet?

Mark

[Tazman1966]

What a great first result! You'll be hooked now!

[PaulR]

Originally Posted by Boom

Lovely work Richard. REAL tellies these are!

One day I will be brave enough to strip the sliders on my B18 for a clean up. How difficult was it?

One day I will be brave enough to tackle a TV. 6kV is scary!!

[Ricardo]

Thanks everyone for all the positive comments.

Dave (Boom), The slider control panel is quite easy to extract. Remove the four nuts and bolts holding it in place and it will pull out to the extent that the wires will allow. I unsoldered all 13 wires from this assembly so that I could work on it more easily. I didn't bother to strip it down any further. I cleaned it initially in an ultrasonic bath. Then sprayed de-oxit on each of the wipers, put a drop of oil on the fixing screws, and slid them up and down until they moved smoothly. In my case it was certainly worth the effort.

Mark, Unfortunately the cabinet is in quite a poor state. One side in particular has clearly been very wet and now has loose and missing veneer. What is worse is that the plywood has also de-laminated somewhat on that side. It is probably fixable, but cabinet repairs are not my forte at all. I will have to give it some further consideration now that the set is working reasonably well electrically.

Tas, You are almost certainly correct. This is very unlikely to be my first and only vintage TV!


Richard

[audiomagpie]

Originally Posted by PaulR

One day I will be brave enough to tackle a TV. 6kV is scary!!

6kV but only a handfull of microamps. No worse than an electric fence or touching the sparkplug on the lawnmower! 'Flyback' EHT generated from a small overwind on the line output transformer won't kill! (But the mains derived EHT on pre war and a very few immediatley post war sets- well that's a different story! I ain't got the bottle for these, or even the funds to buy one come to think of it)!

The main caution with these sets is the mains voltage/live chassis etc., so no more dangerous than a mains radio.

Greg

[PaulR]

Thank you for the encouragement Greg. I would have to learn a lot more about the theory before I tried one. I have always wanted to watch old programmes such as Dr Who on a small screened 1950s set - via an aurora of course!

Paul

[Peter.N.]

Looks as though it has an exceptionally good tube, well done. Believe or not I worked on those sets when they were nearly new.

Peter

[GLENZ32]

What a great picture considering the amount of work you've done on it so far. Very promising start indeed TV collecting does start with only 'one'...then it grows.....and grows.....and grows.....
Cheers Glen

[stacman]

Originally Posted by audiomagpie

6kV but only a handfull of microamps. No worse than an electric fence or touching the sparkplug on the lawnmower! 'Flyback' EHT generated from a small overwind on the line output transformer won't kill! (But the mains derived EHT on pre war and a very few immediatley post war sets- well that's a different story! I ain't got the bottle for these, or even the funds to buy one come to think of it)!

The main caution with these sets is the mains voltage/live chassis etc., so no more dangerous than a mains radio.

Greg

Yes TV EHT scares me too, even if it is low current,
John (Heatercathodeshort), makes me smile, he laughs in the face of high voltage! I used to work with an electrician like that, 'Just plug it in.......it can only go bang',
Regards to all, Alan

[PaulR]

I just read his descriptions of TV restorations in awe and wonder.

[Peter.N.]

I am afraid my philosophy is the same as Johns, when you have worked in the TV trade as long as we have and recieved shocks on a daily basis you get to take no notice, you used to sustain more harm by the sudden involuntary withdrawal of your hand from the cabinet than from the shock itself, there was usually a sharp bracket sticking out to gouge the back of your hand - caution is still advisable though.

Peter