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Old 6th Dec 2017, 10:11 am   #1
Keith
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Default Bush TV22 spares availability?

I am tempted to buy an example of the above, available locally, with a view to restoration to working condition. Can anyone give me an idea of the availablilty of replacement CRT, LOPT etc should such components prove u/s?
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Old 6th Dec 2017, 10:23 am   #2
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Default Re: Bush TV22 spares availability

Hi Keith.

Unless you are very unlucky, the CRT should be fine. The LOPTy can suffer if the set has been stored in damp conditions, but the popularity of the TV22 means that spares are readily available from members here .

I wouldn’t worry about this aspect. The TV 22 is fairly straightforward to restore, there are many threads on here that usually end with a working set.

Go for it!


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Old 6th Dec 2017, 10:34 am   #3
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Default Re: Bush TV22 spares availability?

Dunno about that. I've been looking for a LOPT for mine for a couple of years without success. I don't really want to send it off to Mike or Ed. for a rewind, as it is intermittent and works most of the time.
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Old 6th Dec 2017, 12:01 pm   #4
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Default Re: Bush TV22 spares availability?

An intermittent LOPTx? That's a new one on me.
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Old 6th Dec 2017, 2:12 pm   #5
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Default Re: Bush TV22 spares availability?

One of my TV22's had an intermittent problem with the Lopty, eventually it became a permanent fault! Probably about time I got it re-wound, I was going to try and do it myself, but since decided that would be a very bad idea.

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Old 6th Dec 2017, 2:58 pm   #6
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Default Re: Bush TV22 spares availability?

Richard and Lloyd,

I'd be interested to know the nature of your LOPTx fault. The high peak voltages present usual make an o/c, s/c or insulation breakdown catastrophic.
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Old 6th Dec 2017, 4:18 pm   #7
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Default Re: Bush TV22 spares availability?

My tale is related here:
https://www.vintage-radio.net/forum/...d.php?t=128660

In short I replaced just about everything except the LOPT and the scan coils.
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Old 6th Dec 2017, 9:38 pm   #8
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Default Re: Bush TV22 spares availability?

Hi Gents, most LOPT faults are down to the insulation (paper) on the primary winding carbonising and eventually giving interturn/winding shorts. The symptom of this is a set that initially works and then slowly looses EHT over a period of 15 mins or so. This period gets shorter as the leakage gets worse.
Overwinds are usually OK.

Blocking oscillator and frame output transformers can also fail but are easily rewound.

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Old 6th Dec 2017, 9:47 pm   #9
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Default Re: Bush TV22 spares availability?

Thanks for that.

Yes, I was misled by the word "intermittent" which is one I associate with a degree of randomness. We are talking about a failure after time here and then it works again for a while from cold.

Apologies for taking your thread of topic Keith, but I think your original question was answered.
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Old 6th Dec 2017, 10:04 pm   #10
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Default Re: Bush TV22 spares availability?

Quote:
Originally Posted by Ed_Dinning View Post
Hi Gents, most LOPT faults are down to the insulation (paper) on the primary winding carbonising and eventually giving interturn/winding shorts. The symptom of this is a set that initially works and then slowly looses EHT over a period of 15 mins or so. This period gets shorter as the leakage gets worse.
Overwinds are usually OK.
Ed,

With this being the case it should be possible to repair the transformer using the method here to remove the pitch initially:

https://www.vintage-radio.net/forum/...d.php?t=141634

Then after that, unwinding some of the primary turns from the side initially to free up the overwind, so the overwind is released and preserved, then re-winding the primary and re-fitting the old overwind over the new primary. Then varnishing it.

Does anybody have the primary turns and winding configuration of the TV22 lopt documented ?

I should also point out that the 2uF yoke coupling capacitor was a total disaster from new, it should never have been an electrolytic for this application. Replace it with a 2.2uF 630v poly. I used a Solen Fast.

Hugo.

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Old 6th Dec 2017, 10:32 pm   #11
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Default Re: Bush TV22 spares availability?

I'm looking but can't find it. A few years back there was a guy on here (I'm pretty sure he was Greek or similar) who described rewinding a TV22 LOPT by hand. He rewound ALL of the windings and listed all of the number of turns etc.

Perhaps someone who is better than me at searching can find the post? As I say it would be quite a few years back.

EDIT:- This might be it. The guy is Italian not Greek!

https://www.vintage-radio.net/forum/...ad.php?t=37396
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Old 7th Dec 2017, 12:08 am   #12
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Default Re: Bush TV22 spares availability?

Quote:
Originally Posted by Boom View Post
This is a good thread and its always good to see what patience and hard work can achieve.

Also interesting to note on the initial post, that the 5th photo (on the right) shows the original 2uF coupling capacitor on the yoke assembly with corrosion on one end where some electrolyte had leaked out of it in the past and is eating away the aluminium lip. But it was obviously still working, unless it got replaced before the screen photos were taken.
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Old 7th Dec 2017, 10:55 am   #13
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Default Re: Bush TV22 spares availability?

Thanks for the replies. After the initial optimism, I'm beginning to wonder if this is such a good idea! Although I have good reserves of patience, the work involved in re-winding a LOPT sounds pretty daunting. I would also need to put together a signal source, although I gather that a VHS recorder can be used, possibly with a home constructed modulator (The Aurora is way above my price range!).

My goal was to have the set operating for a biennial village event in the Spring where I put on a display of vintage and military radios together with an amateur radio station. I thought it would be nice to have Tony Hancocks' "The Radio Ham" showing on a vintage TV in the background.

However the thread is obviously arousing a bit of interest and I'm learning a lot. I'll let you know my decision in due course.
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Old 7th Dec 2017, 11:30 am   #14
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Default Re: Bush TV22 spares availability?

Don't let us put you off! I have 2 TV22's and the other one has its original Lopty working absolutely fine, complete with a horrible pitch coating. You will probably want an Aurora for it eventually, they are worth it for vintage telly watching, if you want to use a VHS machine and modulator, the tape will need to have been recorded from a 405 line source. They are fun little sets to work on, go for it!

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Old 7th Dec 2017, 1:29 pm   #15
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Default Re: Bush TV22 spares availability?

Where are you planning to buy the set from? If it's available at auction or in an antiques shop, you can at least confirm the CRT heater is ok by measuring with a DMM. The resistance should be about 3 Ohms. Obviously this isn't possible if you're buying through eBay etc.

Are you able to see inside the set at all? It would be worth trying to see whether the aluminium parts are corroded. A bit of pitting on the chassis floor seems inevitable with these sets, but if it's particularly bad it might indicate damp storage.

I've restored two TV22s. CRT and LOPT were fine both times. Even if the LOPT fails, as others have said, its possible to rewind it or have it rewound.

Laim
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Old 7th Dec 2017, 1:37 pm   #16
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Default Re: Bush TV22 spares availability?

I would not recommend a TV22 as a first attempt at a TV restoration, better to get a mid to late fifties set that is both cheaper to purchase and easier to work on.

I have restored a few TV22/24 variants over the years and have had both LOPT and blocking tx problems, both can be rewound of course, but will add considerably to the cost of restoration.

But don't let that put you off, they are a cracking little set once sorted.

Mark
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Old 7th Dec 2017, 2:19 pm   #17
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Default Re: Bush TV22 spares availability?

Quote:
Originally Posted by mark pirate View Post
I have restored a few TV22/24 variants over the years and have had both LOPT and blocking tx problems, both can be rewound of course, but will add considerably to the cost of restoration.
I was lucky with my TV22, both the blocking osc and lopt were ok.

The TV22 struck me as one of the most interesting and cleverly designed TV sets I had seen, with the chassis stacked on each other, it is amazingly compact and the way the cabinet fits over the chassis is clever.

It makes the TV22 infinitely more compact than any American TV's of the era with the same sized CRT's. They have broad steel chassis and heavy power transformers. Plus the TV22 is much lighter with the absence of a mains power transformer and the aluminium chassis construction.

After all of the vintage TV's I have restored in my time, the TV22 is right up there as a major television technology accomplishment. Then there is the cabinet's artwork or industrial design that makes the set iconic.

So the fact that the lopt or the blocking osc tranys can give trouble wouldn't scare me away, a worthy if not fun challenge to repair.

The only non repairable part is the CRT, that is where any concerns now remain as still there is no CRT re-building service on the planet. And for a good result here, it would have to be a re-screening and re-gunning service. And there would have to be a good supply of P4 phoshor which in itself is a technical challenge to manufacture to get the particle size correct.
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Old 7th Dec 2017, 3:12 pm   #18
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Default Re: Bush TV22 spares availability?

Quote:
The TV22 struck me as one of the most interesting and cleverly designed TV sets I had seen, with the chassis stacked on each other, it is amazingly compact and the way the cabinet fits over the chassis is clever.
I certainly agree, a lot nicer than the TV24 (same chassis) that takes ages to extract the main chassis from the wooden cabinet, leaving the 12" CRT only held by the neck

I was very lucky recently to win a very battered TV24 on ebay for only £9,
It has yielded a Good LOPT, original mains lead & a decent emission CRT.
The cabinet is the only part that is beyond use.

The first TV22 I restored was kept indoors in a dry environment all it's life, which is why the LOPT & blocking TX are still fine.

Decades in a damp loft are a sure sign that you will encounter problems with wound components, "green spot" corrosion is the usual problem with the blocking TX.
Rusted lamination's on the LOPT are a sure sign that if it has not already failed, it soon will....

There are also other problems with poor storage, the plywood pieces seem to be a real delicacy for woodworm and it is not uncommon to find the loud speaker cone rotted away.

Quote:
You can at least confirm the CRT heater is ok by measuring with a DMM. The resistance should be about 3 Ohms. Obviously this isn't possible if you're buying through eBay etc.
This is very good advice, but I have been unlucky enough to find that although the heater showed good continuity, the CRT turned out to be very low emission or down to air

I still have a TV22 in the collection that requires a new CRT.

Mark
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Old 7th Dec 2017, 4:53 pm   #19
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Default Re: Bush TV22 spares availability?

Thanks for the further advice and encouragement - I'm going to have another look at it tomorrow. It's at a sort of upmarket antiques emporium. From a quick look inside, both chassis looked clean. Didn't notice the LOPT condition (although the rear half of the shield was missing). I don't know if the proprieters will allow me to take the back off, but worth a try. Is it possible to probe the CRT heater pins through ventilation holes, I wonder?
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Old 7th Dec 2017, 5:09 pm   #20
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Default Re: Bush TV22 spares availability?

You are far more likely to get a screen damaged by Ion burn than an open heater. This is something you won't see until you have restored the set and all timbases etc are running.

I was ultra lucky and got mine with a perfect crt.
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