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

peter_scott 6th Nov 2019 11:31 pm

Re: Baird T5 restoration project.
 
The old top certainly looks unsavable but the problems of reproducing it are also very real and no doubt give others the same shudders that I get at the thought of having to do it.

Peter

FERNSEH 7th Nov 2019 8:46 pm

Re: Baird T5 restoration project.
 
1 Attachment(s)
Well here goes. The screen aperture will be cut out later today.

DFWB.

PJL 7th Nov 2019 11:33 pm

Re: Baird T5 restoration project.
 
Are you using MDF for the screen aperture? Routing the recess for the glass would be a PITA in ply.

FERNSEH 8th Nov 2019 1:07 am

Re: Baird T5 restoration project.
 
1 Attachment(s)
It's 12mm plywood, the same material as the original was
The next stage is to make the chamfered edges of the screen aperture.
Then, after that's done make the recess for the safety glass.
The router tool will be used for the last two operations.

DFWB.

FERNSEH 12th Nov 2019 2:59 pm

Re: Baird T5 restoration project.
 
1 Attachment(s)
"The next stage is to make the chamfered edges of the screen aperture."

That job was done this morning so the next task is to use the router tool make the 1/4 inch deep recess for the implosion protection window.

DFWB.

FERNSEH 12th Nov 2019 8:36 pm

Re: Baird T5 restoration project.
 
2 Attachment(s)
That's the top panel recreation almost finished, the final stage will be the application of veneers to the upper surface.
No idea what that piece of 90* angle steel came from but it made an excellent guide fence for the router tool.

DFWB.

FERNSEH 12th Nov 2019 11:21 pm

Re: Baird T5 restoration project.
 
1 Attachment(s)
The new top panel is test fitted along with the control board and lower front panel. These are the panels which must be veneered.

DFWB.

1100 man 13th Nov 2019 10:34 pm

Re: Baird T5 restoration project.
 
Excellent work, David. I've been following your progress with great interest. How confident are you with the veneering? That always seems a bit scary to me! What finish will be applied over the veneer?

All the best
Nick

FERNSEH 14th Nov 2019 12:08 am

Re: Baird T5 restoration project.
 
Hi Nick,
In the event that the veneering of the panels doesn't turn out too well I've made duplicates of all the cabinet sections. The veneers supplied to me are book matched so the completed panel surfaces should resemble the originals.
The first cabinet part to receive attention will be the top panel starting with applying veneers to the chamfered edges of the CRT screen aperture.

DFWB.

beery 15th Nov 2019 10:17 pm

Re: Baird T5 restoration project.
 
1 Attachment(s)
Hi all,
I recently obtained a technical book which contained some detail of the early dual standard T5 (I've been after such info for years).
Compare with Peter's diagram in post 155 on page 8 of this thread.
Note that a number of controls are in different places and somehow the two lock controls are in fact one instead.
The set I restored many years ago was made in September 1936, but had obviously been converted in house to single standard (maybe before it was sold?). There were telltale marks where the extra pots had been bolted.
Moving the control markings would have been easy as the engraved plastic labels are simply held in place by the retaining nuts on each control pot.

Cheers
Andy

peter_scott 16th Nov 2019 8:33 am

Re: Baird T5 restoration project.
 
1 Attachment(s)
That's very interesting Andy. There is so little information about the dual standard configuration in the T5. Do you have circuit details? Also, what functions do the three (inaccessible) controls have on the bent over top of the control panel?

So the two blanked off holes were Line Speed A and Line Speed B.

Frame Speed A became 405 Frame Speed
Frame Speed B became 405 Line Speed.
System Switch became Picture Width.

Thanks,

Peter

beery 17th Nov 2019 8:40 am

Re: Baird T5 restoration project.
 
Quote:

Originally Posted by peter_scott (Post 1191960)
That's very interesting Andy. There is so little information about the dual standard configuration in the T5. Do you have circuit details? Also, what functions do the three (inaccessible) controls have on the bent over top of the control panel?

Hi Peter,
I wish I did have the dual standard circuit details. The circuits I have been made on a Bander Duplicator (I think that is what it was called) and were sent to the original owner of the T5 that I restored. They were sent by Bush radio after the war; the timebase circuit states "redrawn 19-2-51" and gives no clue of the dual standard arrangement.
Two of the top controls are coarse line hold and frame hold and the third one is coarse frame height. The set I restored definitely had something in the fourth spot originally.

Going back to the two coarse controls hold, these alone had enough range to get the the Baird timebase frequencies of 25Hz and 6KHz with no other component changes required. Were there four hold coarse controls before (if so was the no coarse height?) or was it only either the line or frame hold that had two coarse settings?
All still a bit of a mystery.

Cheers
Andy

peter_scott 17th Nov 2019 9:58 am

Re: Baird T5 restoration project.
 
Thanks Andy. In the EMI timebases there were resistor changes to alter the blocking oscillator frequencies and feedback capacitor changes at the output stages to compensate for the amplitude changes so I guess the T5 would have something similar.

Peter

Heatercathodeshort 17th Nov 2019 10:31 am

Re: Baird T5 restoration project.
 
2 Attachment(s)
Not a lot of help but I have attached two scans of the original Baird T5 blue print timebases. They are very large and my scanner is A4. dated December 1936 but stamped 1938. Interesting to note the deletion of the 'switch' in Jan 1937. Hope these help. Regards, John.

peter_scott 17th Nov 2019 11:00 am

Re: Baird T5 restoration project.
 
Thanks John. It's just general curiosity on my part rather than a need to know but I find it all very interesting. Although the changes are listed it's strange that they don't reference the components.

Peter

FERNSEH 17th Nov 2019 5:35 pm

Re: Baird T5 restoration project.
 
1 Attachment(s)
Wouldn't be surprised if the 1935 T5 development sets were designed for the 240 line 25 f.p.s. system only and later adapted for dual standard operation.
Baird Television Ltd demonstrated an earlier mirror lid model which might have been the basis of the T5. Pictures of such sets can be found on the internet.
Even J.L.Baird himself conceded that the cathode ray tube was the only practical means of displaying high definition pictures.

The attached picture was posted up at the beginning of this topic.
Compared with the production sets the 1935 prototype doesn't seem to have as many preset controls behind the door.

DFWB.

peter_scott 17th Nov 2019 5:41 pm

Re: Baird T5 restoration project.
 
Going on that photo David you could very well be right. There don't appear to be many controls in the cupboard. Nothing obvious in the "Standards Switch location.

Peter

stevehertz 17th Nov 2019 6:29 pm

Re: Baird T5 restoration project.
 
Quote:

Originally Posted by FERNSEH (Post 1191414)
In the event that the veneering of the panels doesn't turn out too well I've made duplicates of all the cabinet sections. The veneers supplied to me are book matched so the completed panel surfaces should resemble the originals.
The first cabinet part to receive attention will be the top panel starting with applying veneers to the chamfered edges of the CRT screen aperture.

Not quite the same thing but a couple of years ago I re-veneered a hifi cabinet. Here's a link to the trials and tribulations. It's not that difficult if you plan and execute very carefully.

https://www.vintage-radio.net/forum/...d.php?t=130650

FERNSEH 17th Nov 2019 6:36 pm

Re: Baird T5 restoration project.
 
Hi Peter,
The 1935 prototype has the big 15" CRT. BTL experimented with even bigger tubes. Cossor made an electrostatic 14" tube for the model 137T.

DFWB.

FERNSEH 17th Nov 2019 6:47 pm

Re: Baird T5 restoration project.
 
Quote:

Originally Posted by stevehertz (Post 1192441)
Not quite the same thing but a couple of years ago I re-veneered a hifi cabinet. Here's a link to the trials and tribulations. It's not that difficult if you plan and execute very carefully.

https://www.vintage-radio.net/forum/...d.php?t=130650

Hi Steve,
That's an excellent job. Now that last week's Freeview retuning calls have been done this week should be free to make a start on the three panels.
Starting with CRT aperture panel.

DFWB.


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