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Old 4th Aug 2020, 9:21 pm   #1
bionicmerlin
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Default Bush TV 12B To restore or not to restore advice please

I have had this Tv for about 15 years on display unrestored
The lady I bought it from was only just down the road and said her husband was a rep for Philco in the 70s and he found it on a door step just about the be thrown out together witH a KB toaster radioHe took them home and put it in a tin trunk and thatís where they lived for well over 30 years. I got them both for a good price. Infact I offered her what I thought was the going rate but she said it was far to much and wanted me to have it as she Knew I would look after it.
I donít like things not working so just wondering what my options are as to getting it going.
The first major problem is a label on the back from a Tv dealer in Hatton saying faulty LOPT .
The question is should this put me off or carry on knowing the tube could be faulty and maybe more . Obviously the normal things like caps etc as well . Andy
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Old 5th Aug 2020, 6:31 am   #2
mark pirate
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Default Re: Bush TV 12B To restore or not to restore advice please

I have restored a TV12B, Actually not too bad to work on, There is a separate line output & EHT transformer on these sets.
I would start by testing these before anything else.

Here is the link to my restoration, I hope it helps.

https://www.vintage-radio.net/forum/...d.php?t=122824


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Old 5th Aug 2020, 7:01 am   #3
stevehertz
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Default Re: Bush TV 12B To restore or not to restore advice please

Restore it. Why not?!
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Old 5th Aug 2020, 7:12 am   #4
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Default Re: Bush TV 12B To restore or not to restore advice please

I haven't been bitten by the vintage T/V bug yet ,I do remember most of them the first time round ,including the tv12 ,But as Steve said why not ,hopefully the eht tx is ok ,there will be loads of people offering help here ,good luck with it .Mick.
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Old 5th Aug 2020, 11:24 pm   #5
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Default Re: Bush TV 12B To restore or not to restore advice please

Thanks for the replyís
Mark I have had a quick look at your restoration before. This time I have looked at it very thoroughly.
I think I will have a go at restoring it so Iím sure I will require some good advice from the people on here.
It would be nice as well to tell the old lady I got it from its working while sheís still about.
I wonít start it for a few weeks so I can get other things finished so I can have a clear run.
I will probably start a new thread when I get stuck and Iím sure that wonít take long Andy
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Old 6th Aug 2020, 9:00 am   #6
mark pirate
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Default Re: Bush TV 12B To restore or not to restore advice please

Your set certainly is in better shape than mine was, I think these are easier to restore than a TV22, as the RF deck does not need 20+ capacitors replacing.

Good luck with the restoration, these little sets perform well once restored.
I look forward to following your progress.


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Old 6th Aug 2020, 11:49 am   #7
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Default Re: Bush TV 12B To restore or not to restore advice please

Then of course it might Not be duff loptx.
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Old 10th Feb 2021, 1:10 pm   #8
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Default Bush TV 12B again

I have decided to have a go at restoring my TV 12B . Thanks to the encouragement from everyone in my last post back in august.
I decided that I would first build a capacitor reformer . (Paulís design thanks )Not going for my normal approach and just switch on . So far so good as itís on now Reforming I hope.
As in my last thread there was a label on the back saying faulty LOPT.
Taking things apart wires cut and itís been out before . Yes itís definitely faulty.
I believe itís the later version With the yellow spot and extra bleed resistors
I donít know if anyone knows what readings I should be getting but primary is measuring 89K and secondary open circuit.
I only have the manual for the earlier set and it quoted only 92 ohm on the primary .thats a big difference.
I cut the EHT wire off the tube as for fear of pulling the cap off. As the cap fell off the PL38 almost by just looking at it.
I have been over Marks write up a few times.
Any help appreciated but I guess the first thing is to get the LOPT rewound.
Andy
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Old 11th Feb 2021, 9:43 am   #9
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Default Re: Bush TV 12B again

I was lucky with my set, despite the state it was in when I acquired it.
I too have the "yellow spot" transformer.

It should be quite straightforward to rewind, the manufacturers manual is on Jon's site: http://www.thevalvepage.com/resource...ls/manuals.php

Good luck with your set, these are in my opinion, a better built set than the later TV22, the RF deck is a very high quality item with only a couple of caps to change, watch out for dodgy EF50's, I had a couple of duff ones in my set.


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Old 11th Feb 2021, 5:20 pm   #10
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Default Re: Bush TV 12B To restore or not to restore advice please

Mike Barker is very experienced in rewinding these LOPTs, but I'm not sure that he is still working during Covid. Failure of the primary windings is common. Before you invest any more time and money it might be worth putting a tester on the tube, as if that is not up to much a replacement will be hard to source. It's also worth checking the primary of the filed output transformer for continuity as these sometimes go o/c. These are a nice set to restore and are reliable with a good picture once done. Everything is pretty accessible. Key thing is not too mess about with the RF deck too much else you will finish up having to re-align it which is tricky without experience and equipment. As Mark says, apart from perhaps valves there are only a couple of wax caps that should need changing. You will need to change all the wax/paper caps on the main chassis. If you want to maintain the authentic look you can empty out the inners of the caps and hide a modern replacement inside. Good luck with it
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Old 11th Feb 2021, 6:27 pm   #11
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Default Re: Bush TV 12B To restore or not to restore advice please

Good luck with the restoration I’m just doing my first 405 line television at the moment. I hope you can get the LOPT repaired. I do intend to have ago at a LOPT repair myself when time allows. I wonder what you are going to do for a standard converter as I assume it is 404. Keep us posted

chris
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Old 11th Feb 2021, 7:57 pm   #12
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Default Re: Bush TV 12B To restore or not to restore advice please

Hi Andy, with modern insulating materials the transformer should not be too much of a problem to rewind. Let me know if you need any EF50's as I have a good stock

Ed
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Old 12th Feb 2021, 12:35 am   #13
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Default Re: Bush TV 12B To restore or not to restore advice please

Thanks everyone for your tips and advice.
I think Iím going to take a chance on the tube. As itís been proven the reason it was taken out of service is a Faulty LOPT.
All other coils appear to test ok. The set is generally very good . It was stored in a metal trunk for more than 40 years in a spare bedroom. Not some hot and cold loft.
I now have reformed the main caps. (I hope )
I have just checked 2 was caps and expected very leaky. So will change them all in due course.
Chris I have 2 Auroras as I have other 405 line sets.And dual standard
Iím not a expert on repairs just rely on common sense and the experience of others on here. So good luck with yours.
Ed I have messaged you. Andy
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Old 12th Feb 2021, 1:47 pm   #14
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Default Re: Bush TV 12B To restore or not to restore advice please

The line output stage is a development of the circuit employed in the TV1 and TV2 models.
The TV12 has the refinement of having a damper diode across the scanning coils.
Separate flyback and scanning transformers are a feature of this circuit.

DFWB
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Old 12th Feb 2021, 4:44 pm   #15
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Default Re: Bush TV 12B To restore or not to restore advice please

Circuit diagram of the frame timebase.

DFWB.
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Old 13th Feb 2021, 12:05 pm   #16
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Default Re: Bush TV 12B To restore or not to restore advice please

FERNSHE thanks for the extra bit of information.
Iím going ahead and getting Ed to hopefully do a rewind. I will get on with changing the wax caps in the meanwhile. At least with the tag strips itís not easy to make a mistake
Andy
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Old 13th Feb 2021, 3:06 pm   #17
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Default Re: Bush TV 12B To restore or not to restore advice please

Took my Bush TV12B apart yesterday to take pictures of the line output transformers for Ed.
Note the 0.001uF 10KV disc capacitor which is used as a temporary replacement for the leaky TCC Visconol EHT smoothing capacitor.
The set has the Mullard MW22-14C CRT which has no aquadag coating on the bulb.
The rubber insulated wiring is in bad condition and will need replacing sometime.

DFWB.
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Old 13th Feb 2021, 8:17 pm   #18
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Default Re: Bush TV 12B To restore or not to restore advice please

Quote:
At least with the tag strips itís not easy to make a mistake
It can happen, I connected a replacement cap to the adjacent tag during restoration of my TV32, but as only changing a couple at a time, it was spotted quickly!

I always take plenty of photos before starting any work, they have been a real godsend in several cases.


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Old 13th Feb 2021, 10:19 pm   #19
60 oldjohn
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Default Re: Bush TV 12B To restore or not to restore advice please

Quote:
Originally Posted by mark pirate View Post
Quote:
At least with the tag strips it’s not easy to make a mistake
It can happen, I connected a replacement cap to the adjacent tag during restoration of my TV32, but as only changing a couple at a time, it was spotted quickly!

I always take plenty of photos before starting any work, they have been a real godsend in several cases.


Mark
I also managed to get one end of a resistor connected wrong. I aso was replacing two resistors at a time then trying the set noticing gradual improvements, then no raster. If I had replaced most of the caps and a few resistors all in one go I very much my diagnostic skills would have got the set working with my induced fault.

John.
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Old 14th Feb 2021, 2:36 am   #20
bionicmerlin
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Default Re: Bush TV 12B To restore or not to restore advice please

What I do is take photos . Check on diagrams . Find out what each component does. Bit of a learning curve for me.
As I cut the old component out I mark the tag with a black felt tip pen. When I re solder the pen mark disappears when the old solder melts. Then move on to the next..
I would normally do a couple components at a time ,but Itís not practical to keep talking out the bottom rf panel each time and more likely in the end to damage something. Andy
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