Bush TV22 (yes, another one)

[Stubble]

Evening chaps

Thanks for the info, I will spend some time checking again and working though the frame output circuit, I'm assuming the now higher HT and boost HT levels have revealed this fault.

I would like to have the old lady up and running for the August bank holiday, been asked to display my old TV's at the town show day along side the model train displays, would be nice to have her going.

Thanks Lee

[Heatercathodeshort]

Resistors above 100k usually go high. Low value such as 4-68K usually go low especially if they are used in potential divider circuits. Blocking oscillator transformers certainly can do some very odd things before they actually go O/C. A glance through 'Your Problems Solved' in the back of the 50's Practical Television will confirm this. I'm not saying it is the fault in the TV22 but when all else fails you have to push the borders out a bit.
Any frame BO will do as a test. Reverse ONE of the windings if it refuses to oscillate. It will probably produce a non linear picture with maybe lack of height but if the original transformer is the culprit, the jittery effect will be no more. Regards, John.

[Stubble]

Good afternoon

Had a look at the frame circuit again.

R53 220K had gone high
R56 680K had gone low
R57 2.2M had gone low

T4 resistances readings
Primary 521
Secondary 447

So I have changed the three resistors, which has made a small improvement but the raster is still jitter but not as bad and viewable.

I have a Velleman scope HPS10 but I have never used it and not sure where to take the readings, points on the circuit.

Recorded a video and downloaded to YouTube for observations.
Lee

[Stubble]

Video address below.

https://www.youtube.com/watch?v=BMVM...jhBTeS-XFNCqeQ

[Freya]

Fantastic picture, I would advise an attenuator as the aurora will be hammering in the signal. Might be the cause of your previously mentioned cogging. Also I like the way your video camera recorded the line whistle.

[mark pirate]

The picture looks pretty stable in your clip, looks like the CRT is in good shape too

I agree that you should put an attenuator in the feed from the Aurora, the set should work fine with a much lower signal, I use a 9dB with my TV22.

Mark

[Stubble]

Attenuator

Thanks chaps I will take myself along to Maplin’s who sell them and acquire one.

I’m very pleased with this set as it was almost a right off when I picked it up.
Lee

[Stubble]

Chaps I have a few more questions about this smashing little set.

Just noticed that V8 (PL38) line output valve has a blue glow (streak of blue light in one spot) very bright to start with but once the line whistle has started and a raster has appeared on the screen it dulls down, is this normal or a sign of a fault condition?

This valve did have a screening coating on the outside but it has blistered and virtually flecked off completely.

I’m still have frame issues too, difficult to explain but I will try too.

The raster seems to be shrinking and ballooning at the bottom and top only, if I reduce the frame linearity control so that the top of the raster is cramped and also reduce the frame height control so that the castellation are well inside the mask on test card c everything becomes rock steady, it’s viewable but heads and credits shrink and distort at the top of the image, you can see from the photo that the circle is egg shaped, what sort of fault should I be looking for here?

Many thanks Lee

[Lloyd 1985]

Sounds like the height and linearity pots are worn, I have the same problem with one of my TV22's. You could try cleaning them, which might cure it, but new pots will probably be best. As for the blue glow, I've seen blue glows in line output valves before, they are normally not a problem. Yours looks interesting! Not seen it localised like that before, if it works though, I'd just ignore it!

Regards,
Lloyd

[Freya]

My pye v4 does the same thing with its output valve, no cause for concern. Your linearity problem could be man made, looking at post #6 reveals it is not present at this stage of restoration. It might be worth checking for errors in the frame stage resistor / capacitor values.

[Focus Diode]

Excellent result Lee, well done. As for the blue glow in the PL38 I agree this is nothing to worry about. Some valves are prone to this, such as the French Mazda PL504 I fitted in a Thorn 960 and very attractive it looks in my opinion!

Cheers,
Brian