Bush TV22

[Hunts smoothing bomb]

Hi Everyone, Quite a long one this!

I was lucky enough to purchase a Bush TV22 several weeks ago from Martin – “Grindrod” who advertised it in the offered section of the forum (thanks for the set Martin, I’m over the moon with it!) I brought the set home on the Sat 27th Sept.
The set is the earlier version that uses the RF deck which employs the EF91 valves.

The next Saturday I started work on the set, I started by testing about ten capacitors at random with my trusty Nombrex C&R tester that uses around 200v to test for leakage, The answer…….. All bad! I then decided to change every cap in the set (including the heater decouplers in the RF deck) apart from the ceramic types as these usually pose no problem. This took me until Saturday afternoon. After this I inspected the LOPT which was looking quite sorry for itself and I didn’t hold much hope for it! Never the less I checked the mains input selector and powered the set up on the variac with an ammeter in series and at about 170v there was heater glow in the valves and at 180v I heard a faint line whistle begin, this was looking promising I thought. Everything was looking and sounding ok so I gave it full mains, now we had a loud hum from the speaker and very strongly 100Hz modulated line whistle and the ammeter was showing nearly an amp! I replaced the smoothing bomb and that sorted out the hum, line whistle and ammeter but nothing appeared on the screen despite the EY51’s heater glowing. I left it going like this for some minutes and still nothing on the screen so I dug out my EHT probe and took a measurement……. Didly squat! I thought maybe the EY was kaput so tried to draw a spark at the LOP valve anode and the EHT overwind at the EY anode…. Nothing at all. This was my worst (but expected) fear. I went to bed with my mind going round in circles but only coming back saying “it must be the LOPT”.

I have a TV24 that I bought some time ago that had the electronics restored but had been done… let’s say far below my standard and it also has a low tube, the cabinet is fairly tatty too. The main thing though is that someone had made a LOPT for it using the original laminations, new windings sealed in resin and a waste pipe former. I decided it would become a donor set as the TV22 is more valuable, so Sunday morning I decided to start the transplant, it took me until lunchtime to complete and it was also very unnerving having that large naked CRT of the TV24 that overhangs the front of the chassis inches away from me!

I powered up on the variac with brightness down and a line whistle began at around 170v again, hearing this reinforced me that the connections I had made during the transplant were correct so I applied full mains, the EY51 lit and I heard a strong rustle of EHT which pleased me.

At this point I connected the Aurora and selected the correct channel, I could hear the testcard tone clearly. I turned up the brightness and adjusted the contrast and got a picture but it looked very silvery and very very dim with an ion burn about 2 “ big in the middle of the screen. Yes this set employs the “straight gunned” tube MW??-?? I can’t tell you all anything else as the rest of the label has gone.

I thought maybe the EHT was low but this measured 9.5kv. Anyway after prodding round in the back of the set for probably 5 minutes or so I returned to the front and the picture seemed a bit brighter and the ion burn less noticeable. I decided to leave the set on for an hour whilst surfing the net. Well what can I say? What a lovely bright tube that’s what! It has come up a treat and you can’t even see the ion burn at all now unless you have the brightness to high to watch anything on screen.

It is quite interesting as now the tube has come up it has shown another fault, and that is you cannot turn the brightness down enough, a quick measurement revealed the earthy end of the brightness control was open circuit, the donor TV24 supplied a replacement which made things better, It had a problem with frame sync as well as it was very weak, this turned out to be high value resistors in the RF deck so out the deck came and I replaced everything out of tolerance. Whilst the RF deck is out it makes the component side of the main deck accessible too so I did the out of spec resistors here too and slid the RF deck back in and did it’s securing bolts up This is where I made the mistake!

I turned the set back on without the RF deck plugged in! I heard the valve heaters tinkling and turned off but it was too late! When the RF deck was reconnected the set had a very bad mains hum on screen and on the audio, I had damaged the heater cathode insulation!. On the good side of things the frame sync had been fixed and the further replacement of resistors had improved the definition a great deal. I posted a want for replacement valves and must thank Ed Dining and Geoff 555 greatly as between their supplies I now have a full set of good replacements. I replaced the PL38, PZ30 and PL33 and the set now performs very well and has a very good tube and I am very pleased with it. I just have to sneak it indoors now!

Cheers
Lee

[Hunts smoothing bomb]

And more..........

[Hunts smoothing bomb]

And the last lot.

[Tazman1966]

Hello Lee.

You must be really pleased with your efforts. I think it looks great and may even spur me into having something as old myself.

I like the ingeniously recreated LOPT. I wonder if the creator is a member of this forum.

Can't wait to see it in the flesh.

Cheers for the write up matey

[Geoff 555]

Hello Lee Jolly good show, it looks great, very pleased for you.I was wondering how you were doing.
All the best.
Cheers.
Geoff.

[mark pirate]

Lovely job I have an early tv22, reading this has inspired me to
get on with mine, i love the home made lopty case looks very good as well
Well done!

Mark

[chipp1968]

Very good. , now u must do up the 24 again !

[stuie319]

Excellent The restoration, the telly and the write up
Fab result well done!

Regards
Stu

[Hunts smoothing bomb]

Thankyou all for your kind words, It was a joy to do this restoration and gives a wonderful sense of achievement.
I have decided that the TV24 is going to be offered as a spares or repair set so look out in the right section of the forum for it.

Cheers
Lee

[tvden]

interesting to try and find out how the lopt was rewound

[newlite4]

Nice job Lee, great to see these running. Judging by the ammount of "dog ends" in the ashtray, there must have been some stressful moments. Well worth the effort.
Neil