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Old 17th Oct 2019, 11:25 pm   #1
beery
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Default Oh no, my TV22 has failed!

Hi all,
my TV22 just failed whilst showing interludes
I must say, I missed the exact moment it failed as I was watching 'The Circle' at the time. Oh the evils of reality TV...

This sets gets lots and lots of use and has been on the whole very reliable.

The initial symptom is line whistle, but no raster and no sound. So maybe a missing HT rail.

A quick check at trader sheet 1003 (yes, it's sad I've know the number off by heart ) shows that the HT feed to the receiver section comes from smoothing choke L25, so this is my first guess before I have even taken the back off.

Lets see...

Cheers
Andy
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Old 17th Oct 2019, 11:28 pm   #2
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Default Re: Oh no, my TV22 has failed!

Ahh, it can't be L25 as it also feeds the line oscillator...
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Old 17th Oct 2019, 11:37 pm   #3
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Default Re: Oh no, my TV22 has failed!

A quick peek in the back reveals V1,V2 and V3 in the receiver section glowing brightly and all other valves on thr lower deck are not lit.
I suspect C65 or C66 heater decoupling caps. I will take out the reciever section and have a look...

On a side note, all the waxies have been re-stuffed in this set, so we may be looking at a faulty polyester cap.

Cheers
Andy
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Old 18th Oct 2019, 12:01 pm   #4
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Default Re: Oh no, my TV22 has failed!

Hi Andy,
did you restuff the very small 0.003mfd heater decoupling capacitors?

DFWB.
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Old 18th Oct 2019, 12:11 pm   #5
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Default Re: Oh no, my TV22 has failed!

'Flipin eck' Andy!!

No wonder the TV22 gave up! It did it in a state of protest because you took your glance away from it in favour of the circle!!!

My money is on those crusty bakelite Hunts heater decouplers below the RF deck also.

Cheers
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Old 18th Oct 2019, 1:57 pm   #6
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Default Re: Oh no, my TV22 has failed!

Quote:
Originally Posted by beery View Post
A quick peek in the back reveals V1,V2 and V3 in the receiver section glowing brightly and all other valves on thr lower deck are not lit.
I suspect C65 or C66 heater decoupling caps. I will take out the reciever section and have a look...
That won't have done the bright valves any good at all. You may have to replace those three as well.

Change all of those heater decouplers….not worth taking the chance.
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Old 18th Oct 2019, 3:45 pm   #7
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Default Re: Oh no, my TV22 has failed!

Hi all,

Quote:
Originally Posted by Sideband View Post
That won't have done the bright valves any good at all. You may have to replace those three as well.
They should be ok as I turned it off in a matter of seconds

Quote:
Originally Posted by Hunts smoothing bomb View Post
'Flipin eck' Andy!!

No wonder the TV22 gave up! It did it in a state of protest because you took your glance away from it in favour of the circle!!!
Hi Lee,
Yes, I think it serves me right. Actually on balance the interludes were more interesting than the circle

Quote:
Originally Posted by FERNSEH View Post
Hi Andy,
did you restuff the very small 0.003mfd heater decoupling capacitors?

DFWB.
Well David,
You hit the nail on the head. I do indeed have egg on my face now as it turned out that I had only replaced some of the capacitors in the RF deck. If I had restored the set for someone else, I would have replaced them all.
Mind you it suggests that the those TCC waxies are not all that bad. I restored this particular TV22 about 10 years ago and it has put in many hours of operation including a few hours without my attention at my Wedding reception.

Anyway. Photos...
The first picture shows the fairy light display.

The second shows the faulty C65, the lower 3nF capacitor in the picture.

The third picture shows a new capacitor wearing a waxie jacket. The new component being a little too big.

The fourth picture shows the re-stuffed cap back in place. I won't stop there though, but will replace more - maybe all the remaining waxies before I power the set up again.

Cheers
Andy
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Old 18th Oct 2019, 4:00 pm   #8
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Default Re: Oh no, my TV22 has failed!

Well, apologies for being a Joab's comforter, but like I keep saying time and time again, just change all waxies on sight! With waxies it's not a question of if it will fail, it's when. And even if a waxie doesn't 'hard' fail, it may be operating as a different component(s) to what should be in there. Ok, you're gonna fix this fault I'm sure, but it may have caused damage elsewhere in the process. Best of luck getting it going again anyway.
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Old 18th Oct 2019, 7:01 pm   #9
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Default Re: Oh no, my TV22 has failed!

Quote:
it's not a question of if it will fail, it's when.
Very true, I always replace all waxies on sight. All three of my TV22's are full of nice new yellow caps, I don't see the point in restuffing sets that are as commonplace as a TV22, however, any rare sets and all my prewar radios do get restuffed.

As we all know the modern caps are so much smaller than the originals, although it is not the case with those 0.003mfd decouplers!

Mark
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Old 18th Oct 2019, 7:23 pm   #10
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Default Re: Oh no, my TV22 has failed!

This was the very fault situation I described in the other TV22 thread! My set also worked OK for a while until this happened, in my defence I was new to vintage TV's at the time, and had very little idea about restoring it, I was just pleased it still worked at all! That particular TV22 is still with me, and still working, had it since 2003, did some cap changing around 2007 (I think?! might have been earlier!), then finished it in late 2008, when I finally got an Aurora. I think it's time I re-visited the set, as a few annoying niggles have surfaced over the years, most annoying is jiggling height, which I'm hoping is just the height pot needing a clean.

Regards,
Lloyd
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Old 19th Oct 2019, 6:50 am   #11
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Default Re: Oh no, my TV22 has failed!

This thread helps answer the question in another recent thread about the TV22.

Definitely the set needs an entire re-cap, the waxies, any other capacitors and all the electrolytics, or a disaster awaits around the corner.

I tend to replace heater bypass caps and screen bypass with dipped silver mica 500V rated parts, the mil spec ones are the best. I ignore whatever the manufacturer put in there and I don't use poly caps for these locations.

Then you will never likely have any trouble. If a heater bypass cap shorts, it could take out non renewable resources, like valves, and heaven forbid, the CRT, though less likely being at the chassis end of the chain. So it really important all the caps are dealt with before the power is applied.

I said "never likely have any trouble", because, no capacitor is perfect. In a batch of mil spec dipped silver mica caps I got a year or so back, one was shorted out from new, I could hardly believe it, luckily I detected it before it was used.

Fortunately, the situation is more forgiving with resistors, and if they go open or high R, seldom does damage result.
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Old 19th Oct 2019, 10:19 am   #12
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Default Re: Oh no, my TV22 has failed!

Quote:
Originally Posted by mark pirate View Post
Quote:
it's not a question of if it will fail, it's when.
Very true, I always replace all waxies on sight. All three of my TV22's are full of nice new yellow caps, I don't see the point in restuffing sets that are as commonplace as a TV22, however, any rare sets and all my prewar radios do get restuffed.

As we all know the modern caps are so much smaller than the originals, although it is not the case with those 0.003mfd decouplers!

Mark
Ah, but the thing is that all those "rare & pre-war" sets were just as commonplace as the TV22 at one time... There's one to think about!

Cheers
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Old 19th Oct 2019, 11:14 am   #13
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Default Re: Oh no, my TV22 has failed!

Er, no they weren't! Not any point in their lifetime!
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Old 19th Oct 2019, 11:37 am   #14
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Default Re: Oh no, my TV22 has failed!

Quote:
Originally Posted by Hunts smoothing bomb View Post

Ah, but the thing is that all those "rare & pre-war" sets were just as commonplace as the TV22 at one time... There's one to think about!

Cheers
But we have to look at was is actually left.

I read that some of the American pre WW-2 TV sets, like the Meissner and the Andrea, there are less than 20 known to exist of each model. This makes them much rarer than any Violin model made by Stradivari.

Apparently there might be something like 40 HMV 904/905 sets left in the world.

There are obviously a lot more TV22's and other post war sets. At least now their value is recognized so the remaining ones will likely be saved.

One problem in America was that pre WW-2 TV sets, all had AM sound. Post WW-2 they went straight to FM sound in the USA. Even RCA's 621TS set (1946) had FM sound. So most of the pre-WW2 sets got sent to the dumps in the USA.
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Old 19th Oct 2019, 10:59 pm   #15
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Default Re: Oh no, my TV22 has failed!

Some of the early American sets seemed to be regionalised in their sales, California based Hoffman mostly marketed TVs in the western states & are rare to find elsewhere.
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Old 22nd Oct 2019, 1:27 am   #16
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Default Re: Oh no, my TV22 has failed!

Quote:
Originally Posted by Hunts smoothing bomb View Post
Ah, but the thing is that all those "rare & pre-war" sets were just as commonplace as the TV22 at one time... There's one to think about!
Hi Hunts smoothing bomb. I think you hit the nail on the head there. Whilst I don't think that TV22s are becoming rare, I do think that one day it might be hard to find any that still have waxies left in them.
When I got my first TV22 almost 30 years ago, I did indeed put all new caps in it as well as re-winding the inner windings of the lopty.
However I eventually decided to sell that set and start off with a fresh one in order to re-stuff the waxies. Hmm I do like to see waxies, a bit of dust and a few dead spiders (though I seem to find more spiders in radios than in TVs...)

The picture shows the first batch of re-stuffed waxies. I've now completed the third and final batch. So the set should be up and running again in the next couple of days or so.

Cheers
Andy
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Old 25th Oct 2019, 8:46 pm   #17
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Default Re: Oh no, my TV22 has failed!

Hi all,
I decided to replace all the remaining waxies in the RF deck by re-stuffing the original caps.
I completed it last night and the set now works again and I hope it will work for many more years before it breaks down again.

The first photo shows a part view of the RF chassis with the re-stuffed capacitors.

The second is of course test card C.

The third photo is of something that happened in 1953.

The fourth photo is from a 1954 BBC drama featuring Peter Cushing. Can you tell what it is?

Cheers
Andy
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Old 25th Oct 2019, 9:07 pm   #18
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Default Re: Oh no, my TV22 has failed!

Andy,

Nice job. Nice result!

1984?

Steve
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Old 25th Oct 2019, 9:38 pm   #19
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Default Re: Oh no, my TV22 has failed!

And another vote for 1984. (When big brother turned off 405 lines.)
Those waxies look super!

Peter
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Old 25th Oct 2019, 9:42 pm   #20
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Default Re: Oh no, my TV22 has failed!

Quote:
Originally Posted by beery View Post
Hmm I do like to see waxies, a bit of dust and a few dead spiders (though I seem to find more spiders in radios than in TVs...)

Andy
Andy,

I've never much liked the way waxies attract dust and dirt. When I re-stuff the ones for my restorations (photo attached) I heat the empty tubes until the wax just melts and wipe them off with a paper towel. To re-stuff them I insert the new capacitor with some fibreglass tape around it to be a push fit (and create a seal) then I pour polyester resin into each end on alternate days. It tends to have a wax look to it, but is non-sticky. Then I varnish the capacitor body with marine spar varnish, which is miscible with the the wax cardboard surface and sticks really well to it. When that dries the capacitor's surface is non-sticky, so dust does not collect on it much, like the waxies.

The only thing is, it makes the finished result just a tad more shiny than the original part, but that doesn't bother me. Over a decade has past since I started restoring waxies like this and all the ones I have done this way still look perfect.

Also on that under-side chassis photo (a 621TS) if you look closely you with see the type of dipped mil spec mica caps I use on the heater and screen grid bypass points.

Hugo.
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