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Bush tv24a lives again

 
VintageRob
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Morning all.

 

I thought I'd mention a little fix I did last week on a poorly tv24a.

These have a completely different lopt and scan coils to the tv24. 

The set was working well after it'd had been re capped and fettled, but there was a fizzing on the picture every now and then that was getting worse. 

Anyway, I could see a nice blue corona from the overwind on the lopt. Sadly it was breaking down and needed to be replaced. 

Sadly I didn't have a replacement, so started head scratching....eventuality I cane across the idea of using a lopt from a later tv62. I carefully removed the lopt from the tv62s housing. I then carefully removed the winding for the eht rec heater as I wanted to use the original one fron the tv24a.

I had to mount the replacement lopt vertically on the tv24 housing and after a little drilling got it fitted. 

10kv of eht and a wonderful picture greeted me at switch on, but a slightly different fizzing was still visible on screen. So, I replaced the scan coils from the donar tv62 and success. A stable bright picture. 

So, if all is lost for your tv24a in the line department, I can recommend a later Bush lopt.

I have attached a few pictures, but sadly forgot to take them before I put the chassis back in the cabinet.

 

I hope this mod might help others.

IMG 20180903 092906
IMG 20180903 092819
IMG 20180903 092847
IMG 20180903 092835

TTFN. 

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Topic starter Posted : 03/09/2018 9:30 am
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Cathovisor
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Given Bush often trialled the parts for a forthcoming development in an existing chassis, I'd have a quiet shilling on what you originally had were the coils and LOPT that later went into the TV43. 

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Posted : 03/09/2018 9:42 am
VintageRob
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Ahhhh.

That makes sence. It is now showing a lovley picture. The LOPT was a little different, in as much as the EHT overwide was wound on top of the primary on the TV62, but on the TV24a it was about 2cm away from the primary, but the data for the two coils was very similar.

It is fitted wiht a re-gunned CRT, which shows almost new on the tester, so heres hoping it provides many years of happy viewing again!

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Topic starter Posted : 03/09/2018 10:25 am
Cathovisor
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I'm sure under your care it will, Rob! 

I wonder how similar the ITV-capable TV24C is to a TV43? I have a TV36C that is similar to the TV43 (17" tube though)... by far and away the one to catch people out is the TV 12AM - which has the time base chassis and "Double-D" mask of the TV22, but has the TRF receiver chassis! 

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Posted : 03/09/2018 10:46 am
VintageRob
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....that's one to lookout for then! I do love Bush TVs. They just seem so well built and lovely to service. 

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Topic starter Posted : 03/09/2018 11:21 am
Cathovisor
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Posted by: VintageRob

....that's one to lookout for then! I do love Bush TVs. They just seem so well built and lovely to service. 

Hi Rob,

your opinion of being 'easy to service' might change if you ever restore a TV1. They are amazingly hostile towards the poor service engineer! 

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Posted : 03/09/2018 11:49 am
VintageRob
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I can dream (or maybe have nighmares now you've said they are tricky) of getting my hands on one!! I've never been lucky enough to get near a pre-war Bush TV.

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Topic starter Posted : 03/09/2018 1:10 pm
Cathovisor
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Posted by: VintageRob

I can dream (or maybe have nighmares now you've said they are tricky) of getting my hands on one!! I've never been lucky enough to get near a pre-war Bush TV.

The TV1 (and its 12" sibling, the TV2) are post-war - about 1948. In addition to being a pig to work on, there's a sheet of metal-backed asbestos acting as a heat shield to the receiver as it sits above the power supply and other high-power valves! Also, Bush got the design of the superhet sound channel sufficiently wrong to warrant making a TRF sound chassis available to retrofit - my own TV1 has one of these.

As for a pre-war Bush... this is where it gets complicated. Strictly speaking, the only pre-war Bush TV badged as such never got further than a few prototypes shown at Radiolympia in 1939 (this is why I borrowed that magazine from you, and I haven't forgotten about it!) - this was the P63.

However.... Bush did make television sets before the war - on behalf of Baird. This was a result of an effort between Cinema Television (Baird's company) and Bush, with the Ostrer brothers (who owned Bush via Gaumont British). Baird had the capacity to make CRTs, but no other manufacturing capacity. This is where Bush got involved - they made the sets to Baird designs.

In the spring of 1939 Baird announced they were setting up their own manufacturing facility and the link with Bush ended. 

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Posted : 03/09/2018 1:42 pm
VintageRob
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Cathovisor....you are a font of knowledge! I'm glad you enjoyed the mag. 

I've never had the pleasure of anything pre-war. One day I may get lucky, or I'll re-mortgage the house and buy one!!

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Topic starter Posted : 03/09/2018 2:16 pm
Cathovisor
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Posted by: VintageRob

I've never had the pleasure of anything pre-war. One day I may get lucky, or I'll re-mortgage the house and buy one!!

They are becoming less sought after, I think. Fewer collectors are showing interest in them primarily due to size and the danger element - but prices are down on what they were even a few years ago. Still in four figures mind, but with the odd exception I think the five-figure days are gone: much like the days of four-figure Marconi V2s in the radio field. 

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Posted : 03/09/2018 3:58 pm
TVJON74
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Posted by: Cathovisor

by far and away the one to catch people out is the TV 12AM - which has the time base chassis and "Double-D" mask of the TV22, but has the TRF receiver chassis! 

I have a TV12AM in the pile. Did they make very many of them? I wonder if they were made to use up the old RF decks from the TV12 put together with the top deck of the new TV22. The reason for this assumption is that my back cover has a little badge on the back saying TV12AM (made from the same stuff as the rear cover and secured with 2 little metal fingers that fit into slots in the rear cover and then folded over to fix in place) underneath this is stamped on TV22 so they must of been ready to make TV22's but we're still selling / making TV12AM's. If that makes sense?

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Posted : 03/09/2018 9:52 pm
Cathovisor
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No idea - but it warranted a manual supplement. As mentioned elsewhere, the TV24c is close to the TV43 in construction too. Every TV12AM has that metal badge, and there are other Bush sets (both radio and TV) where you will either see these little badges or even over-printed backs - one set I own has "EAC91" on its back, but this has been over-printed.

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Posted : 03/09/2018 9:55 pm