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-   -   Baird T5 restoration project. (https://www.vintage-radio.net/forum/showthread.php?t=152005)

FERNSEH 3rd Dec 2018 10:54 pm

Baird T5 restoration project.
 
2 Attachment(s)
As you can see from the pictures this Baird T5 TV set has a problem with the cabinet. Woodworm! In fact I reckon the cabinet is in a worse state than the HMV 900 that appeared on this Forum back in 2011.
The two power supply assemblies were removed today only to discover that the cabinet floor is completely rotten and it's likely so is the shelf that supports the timebase chassis and the separate vision and sound receivers.

It's going to be a complete cabinet rebuild.

Note the "Televisor" emblem instead of the usual Baird brand name. There is a small label inside the cabinet informing us that the set was made by Bush Radio Ltd.

DFWB.

mark pirate 3rd Dec 2018 11:37 pm

Re: Baird T5 retoration project.
 
Now that's what I call a winter project David, lets hope the electronics are in better shape than the cabinet!

I am sure that I read somewhere that Baird sets of this era were built by Bush.
:beer:
Mark

FERNSEH 4th Dec 2018 2:17 am

Re: Baird T5 retoration project.
 
1 Attachment(s)
Hi Mark,
Here's the evidence that the set was made by Bush Radio.
The CRT was made by Baird Television Ltd, Cathodevisor type 15MW1

DFWB.

Jac 4th Dec 2018 8:11 am

Re: Baird T5 retoration project.
 
That's a very interesting set David.
I'm going to follow this restoration!

Jac

mark pirate 4th Dec 2018 9:20 am

Re: Baird T5 retoration project.
 
More evidence of it being built by Bush is seen in the chassis construction quality. it had certainly gone down hill in post war Baird sets, my T164 is proof of that :-)

I would dearly love to have a prewar set to restore, but sadly well out of my budget!

I look forward to following your progress with this rare beast.
:beer:
Mark

Heatercathodeshort 4th Dec 2018 10:12 am

Re: Baird T5 retoration project.
 
Those connectors to the power supply look almost identical to the ones employed in the Bush T91/TV1/2 models of 1947/48.

A massive undertaking David. I would guess that most of the cabinet is infested. The power supply is usually reliable with a very well made EHT transformer.

Realistically about a years work given time off to recover. Regards, John.

Tractionist 4th Dec 2018 10:55 am

Re: Baird T5 retoration project.
 
Mein Gott! (As they say in Blaydon .....).

You do 'dig 'em up David !!!!

ianm 4th Dec 2018 11:02 am

Re: Baird T5 retoration project.
 
Great stuff! Wasn't this set the subject of a thread entitled "Baird T5 garage find", back at the beginning of July?

FERNSEH 4th Dec 2018 11:33 am

Re: Baird T5 retoration project.
 
Here's the link:

https://www.vintage-radio.net/forum/...d.php?t=147823

DFWB.

Brigham 4th Dec 2018 1:40 pm

Re: Baird T5 retoration project.
 
Is the Dual-Standard switch still fitted?

linescan87 4th Dec 2018 1:49 pm

Re: Baird T5 retoration project.
 
No one can say you don't like a challenge! Good luck with it, I'll be following this thread with interest.

How do these early Baird CRT's hold up?

Regards,
John Joe.

FERNSEH 4th Dec 2018 2:37 pm

Re: Baird T5 retoration project.
 
1 Attachment(s)
From Television and Short Wave News. A prototype Baird T5.

DFWB.

beery 4th Dec 2018 3:24 pm

Re: Baird T5 retoration project.
 
Hi David,
I'm glad you have been able to get the chance to restore this set.
I was tempted to have a go, but I don't have your cabinet skills. Also renting a very small Edwardian house with hardwood flooring and no external storage really puts me off anything with woodworm at the moment.

I look forward to seeing how you get on with it.

Hi Jon Joe,
The Baird tubes seem to have had a fairly short working life, but I can tell you that having restored a T5 with a good CRT that they are capable of really excellent pictures.

Cheers
Andy

Panrock 4th Dec 2018 4:22 pm

Re: Baird T5 retoration project.
 
Quote:

The Baird tubes seem to have had a fairly short working life, but I can tell you that having restored a T5 with a good CRT that they are capable of really excellent pictures.
I'll second that. There was a working T5 at the Science Museum Exhibition (re. Gordon Bussey) in 1980, and the picture was bright and sharp... the picture looked big for a pre-war set too.


Steve

FERNSEH 4th Dec 2018 5:17 pm

Re: Baird T5 retoration project.
 
That's right a 15" CRT in a pre-war TV was a really big screen, typically 10 X 8 inches. Didn't Baird Television Ltd make a speciality of making really large CRTs? Isn't there a story about 22" round tube being made.

The Cathodevisior tubes fitted in the T5 had directly heated cathodes which means the video drive must be supplied to the grid or as it was called then, the Wehnelt electrode.

DFWB.

peter_scott 4th Dec 2018 5:31 pm

Re: Baird T5 retoration project.
 
I'm really looking forward to this restoration too.

Peter.

Heatercathodeshort 4th Dec 2018 6:58 pm

Re: Baird T5 retoration project.
 
David takes these rotten wrecks in his stride. Think of it as a little puppy with wagging tale that you dragged out of the river when only 100 yards from the weir.

John Joe, Its not really a case of holding them up, more a case of don't let go. If I discover bits of a 15MW-1 on my grass I will know David did in fact let go. Regards, John.

Nanozeugma 4th Dec 2018 9:01 pm

Re: Baird T5 retoration project.
 
My word, this really be a project and a half (which I shall follow with great interest.

Magpie66 4th Dec 2018 9:12 pm

Re: Baird T5 retoration project.
 
Thanks Beery for recommending Dave,He certainly knows his stuff.
We are certainly looking forward to following the restoration on the forum and seeing the end result.
After reading the comments on the original post”Baird T5 garage find”, I feel privileged to own this important piece of history. Thanks for your commitment Dave.

Ant

FERNSEH 4th Dec 2018 9:37 pm

Re: Baird T5 retoration project.
 
Hi Ant, About 80 per cent of the cabinet will need renewing and to do the job properly the correct materials will have to be found. The cabinet floor and shelf require furniture quality 15mm plywood. The cabinet sides and front panel use much thinner plywood. The cabinet mirror lid can be saved but will need re-veneering. Strange some wood parts have not been attacked by the woodworm.

DFWB.

FERNSEH 6th Dec 2018 11:50 am

Re: Baird T5 retoration project.
 
1 Attachment(s)
Quote:

Originally Posted by Brigham (Post 1098005)
Is the Dual-Standard switch still fitted?

Hi Colin, There is no evidence of any components in the timebase chassis ever been fitted for the 240/25 Baird system.
In 1947 the receiver was returned to the works for a complete overhaul. New electrolytic capacitors fitted and a number of modifications carried out to improve reliability. For example, 50 ohm resistors fitted between the anodes of the IW4-350 HT rectifiers and the secondary of the mains transformer. The replacement electrolytic capacitors are of TMC make, dated 1947.

The 2.5volt CRT filament is suppled from a separate winding on the mains transformer. In series with the CRT filament is a variable resistor. This component has gone high value so the CRT filament was underrun.

The attachment shows the timebase and receiver units have been successfully removed from the cabinet. The wooden shelf is close to disintegration, another part to replicate.

DFWB.

FERNSEH 6th Dec 2018 7:33 pm

Re: Baird T5 retoration project.
 
Testing the HT and heater supply power supply unit. The smoothing capacitors are useless and will not reform. Two 16microfarad 450volt capacitors and one 24microfarad 450volt electrolytic capacitor are required. The 24mfd capacitor will be replaced by an 8 + 16mfd component.

With the two Mullard IW4-350 HT rectifier valves removed 360 VAC can be measured at the anode connections of the rectifier valves.
The mains transformer runs cool, so it's likely there will be no problems with that component.

The 5KV EHT unit will receive attention next.

DFWB.

FERNSEH 7th Dec 2018 1:28 pm

Re: Baird T5 retoration project.
 
3 Attachment(s)
Results of last night's work. The EHT is delivering 5KV which I believe is the correct figure. A bleeder resistor chain consisting of five 2Megohm resistors is connected across the EHT supply. All the resistors have gone high in value and will have to be replaced.

The timebase and receiver unit baseboard is beginning to disintegrate, see third picture.

DFWB.

mark pirate 7th Dec 2018 8:33 pm

Re: Baird T5 retoration project.
 
Good news that the transformer looks OK, I guess you have tested the CRT filament?
You certainly have a task to rebuild the cabinet, looks like the only thing keeping it together is the woodworm holding hands!
:beer:
Mark

Heatercathodeshort 7th Dec 2018 8:54 pm

Re: Baird T5 retoration project.
 
The 'works' looks fine David. I would imagine that with some hours of dedicated work, this should revive well.

That cabinet is really bad. Those wood pests love the animal glue used in the manufacture of plywood.

The suspense is just too much... Can you please connect that EHT supply to the CRT and see if you get a 'blob'. Is it an original Cathovisor tube or a post war replacement. Time to put on your bomb disposal work gear. John.

line sync 7th Dec 2018 9:09 pm

Re: Baird T5 retoration project.
 
Hi David
Well you have certainly taken on a big job here but we all know that your the man to rebuild it , I will also be following this.
I have a question , I notice your using your trusty rank EHT meter to measure the EHT , well I was told you couldn't use these type of meters for testing mains EHT sets and if I remember correctly the correct one is an electrostatic meter?

Robin

FERNSEH 7th Dec 2018 10:21 pm

Re: Baird T5 retoration project.
 
Hi Robin,
I've been using the RBM EHT meter getting on for forty-five years.

I'm sure the load that the meter imposes on a mains derived EHT system is negligible. The source impedance of EHT from a mains transformer is far less than any flyback EHT system, be it colour or black and white TVs.

Electrostatic meter explained:
https://en.wikipedia.org/wiki/Electrostatic_voltmeter

DFWB.

line sync 7th Dec 2018 11:11 pm

Re: Baird T5 retoration project.
 
Thanks for that david , I now know I can use my rank EHT meter on mains eht sets.
Getting back to the Baird , can you still buy the right kind of plywood ?
I know this sounds a silly question when you can walk into any DIY shop and buy ply off the shelf but its not the same stuff.
Have you got a stash of 1940/50`s wardrobe doors and side panels ?

Robin

rambo1152 7th Dec 2018 11:52 pm

Re: Baird T5 retoration project.
 
I can imagine Dave walking in to his local charity shop, calipers in hand.

I suspect the advice not to attempt to measure mains derived EHT by one means or another, is given purely on personal safety grounds.

Heatercathodeshort 8th Dec 2018 10:21 am

Re: Baird T5 retoration project.
 
Just a word of warning here.

For those not familiar with mains derived EHT systems. These are lethal if stringent precautions are not observed. Great care has to be taken when servicing including the stability of the chassis that can fall and trap the unwary with very dangerous results.

O/C bleeder networks and poor insulation are very real hazards.

Just this week I had a very odd incident involving a PYE D16T and a glass mirror. I won't bore you with the details but it just went to prove how very careful you have to be.

The D16T particularly can be a very dangerous receiver in the wrong hands but any 50c/s mains derived high voltage power supply has to be treated with the utmost of caution.

Play safe! John.

Ian B 8th Dec 2018 9:55 pm

Re: Baird T5 retoration project.
 
Regarding plywood: what you need is Birch Ply. It's available in thicknesses from 3mm upwards, and a good timber merchant should be able to order it for you. There are different grades according to whether you need a totally un-blemished surface or not; obviously when veneering over it, a few filled knot holes won't matter.

Unlike the cheap Asian ply, the individual plies are all the same thickness, so it's much stronger. Naturally, it's quite a bit more expensive!

Ian Blackbourn

FERNSEH 8th Dec 2018 11:21 pm

Re: Baird T5 retoration project.
 
2 Attachment(s)
Hi Ian,
Good quality birch plywood is available from at least two timber merchants in Gateshead. On Monday I'll make more enquiries. The plywood is usually sold in 1200 X 2400mm or if you prefer 8 X 4feet sheets.

Rambo1152 wrote: "I can imagine Dave walking in to his local charity shop, calipers in hand."
I've found some useful pieces of veneered wood, a bed headboard and another piece removed from a table. Sadly neither is any good for the restoration of the Baird T5 TV.

A picture of the underside of the timebase unit.

DFWB.

peter_scott 9th Dec 2018 9:31 am

Re: Baird T5 retoration project.
 
Looks like a horrible thing to work on.

Peter ???

Heatercathodeshort 9th Dec 2018 10:15 am

Re: Baird T5 retoration project.
 
2 Attachment(s)
Hello David,
That under chassis view looks remarkably clean. I think the majority of the work will be from your cabinet maker experience.

Oh, by the way. I'm sending up some timber that may be of use.

[Huge Oak tree that was felled last week in the lane. 380+ rings counted and the trunk alone weighed around 18 tons. Massive bracket fungus around the base, the biggest the guy had seen and a rotten core. Terrible shame and the end of a bit of history.]

Is there room to park an artic at the back of your shop?
Regards, John.

FERNSEH 9th Dec 2018 2:42 pm

Re: Baird T5 retoration project.
 
Quote:

Originally Posted by peter_scott (Post 1099522)
Looks like a horrible thing to work on.

Hi Peter,
The can type electrolytic capacitors are post-war replacements for the card box types.
The line output transformer is subject to a high voltage flyback pulse which could result in the possibility of insulation breakdown. It will be a good idea to warm it up to drive out any moisture.

DFWB.

beery 10th Dec 2018 1:27 am

Re: Baird T5 retoration project.
 
1 Attachment(s)
Hi David,
Here is a photo of how the timebase would have looked with the original caps.

Cheers
Andy

FERNSEH 10th Dec 2018 1:35 am

Re: Baird T5 retoration project.
 
Hi Andy,
that's how the timebase chassis looked like in my Baird T23. I still have the old capacitors and intend to rebuild them so to return the chassis to it's original appearance.

DFWB.

Ted Kendall 10th Dec 2018 7:44 am

Re: Baird T5 retoration project.
 
Is there not some virtue in restoring the set to its 1947 factory overhaul state?

FERNSEH 10th Dec 2018 11:00 am

Re: Baird T5 retoration project.
 
Hi Ted,
That's what I intend to do with the Baird T5 because the work carried out in 1947 was done to a very high standard.
However, My T23 did have all the original card box electrolytic capacitors which were of course useless. It might make sense restuffing those.

DFWB.

Ted Kendall 10th Dec 2018 1:43 pm

Re: Baird T5 retoration project.
 
With you. Should have paid more attention...:-]

FERNSEH 10th Dec 2018 10:05 pm

Re: Baird T5 retoration project.
 
1 Attachment(s)
Check out that fifteen inch diameter CRT. Isn't that one scary thing! Tube is 36 inches from base to screen.
Now I have to find some way of getting it out of the cabinet.

DFWB.

Lloyd 1985 10th Dec 2018 11:56 pm

Re: Baird T5 retoration project.
 
I’m not normally one to be a wuss around CRT’s, but that one is a little scary! And what an interesting set to get to work on, I’m sure it’s going to look fantastic when it’s done :)

Regards
Lloyd

beery 11th Dec 2018 2:55 pm

Re: Baird T5 retoration project.
 
Hi David,

I think that you have only two options:-

1. Lift it out vertically with help and place it vertically into a custom wooden storage frame.

2. Create a frame around the tube whilst it is within the cabinet. Perhaps with some wheels (roller skates?) attached to the tube neck. Then turn the cabinet on its side and ease the tube out.

Personally I think option no.1 is more predictable and safe.

Cheers
Andy

FERNSEH 12th Dec 2018 9:25 pm

Re: Baird T5 retoration project.
 
2 Attachment(s)
Hi Andy,
I reckon option 1 will be the best approach to removing the CRT.
Meanwhile, I'm constructing the special receptacle to keep the tube safe while it is outside the cabinet.
The attachment shows that the CRT is quite easy to lift out. However, what I did find with the T23 it was the reinstallation of the tube that required special care. Guiding the tube neck through the focus coil can be a difficult task.

The tube is a Cathodevisor type 15MW4 and is likely to be a post-war replacement.

Argus25 13th Dec 2018 12:28 pm

Re: Baird T5 retoration project.
 
Wow, That cathode ray tube is really something to behold, a thing of true beauty and a big bubble of evacuated space-time. It is a good thing it is in good hands. Whatever method you use, just do everything really slowly with a good plan and wear safety glasses.

FERNSEH 13th Dec 2018 9:00 pm

Re: Baird T5 retoration project.
 
2 Attachment(s)
-also a face visor for extra safety.

And here it is, the special cradle to be used to keep the CRT safe and secure while it is removed from the set.

DFWB.

Heatercathodeshort 13th Dec 2018 9:16 pm

Re: Baird T5 retoration project.
 
What is that David?

All it needs is a pail in the middle and you have an emergency camode.

Was it necessary to wall paper it?

Seriously that tube is frightening. I thought the CRM151 was bad enough, even it's smaller sister the CRM152B but that monster is something else! Take care David. Regards, John.

petertheorgan 13th Dec 2018 9:16 pm

Re: Baird T5 retoration project.
 
so thats what's happened to the old coffee table radio from Warnham

FERNSEH 13th Dec 2018 9:39 pm

Re: Baird T5 retoration project.
 
Hi John and Peter,
The wallpaper covered plywood was removed from the inside of the green Decca 121 cabinet. That set was the subject of a topic in this forum last year.

DFWB.

Catkins 14th Dec 2018 5:24 am

Re: Baird T5 retoration project.
 
Quote:

Originally Posted by FERNSEH (Post 1100193)
Check out that fifteen inch diameter CRT. Isn't that one scary thing! Tube is 36 inches from base to screen.
Now I have to find some way of getting it out of the cabinet.

Is this an electromagnetically deflected and focused CRT, or electrostatic? It seems very long for an electromagnetic CRT? Just curious.

Phillip


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