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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 14th May 2019, 8:12 am   #161
peter_scott
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Default Re: Baird T5 restoration project.

I wonder if the Baird line timebase was more stable than EMI's or just didn't rely on having line syncs or whether they just perceived a little disturbance at the top of the picture as a minor problem relative to the types of issue raised by Cossors concerning the Baird transmitted signal.

Did the Cossor line timebase make any special arrangement to maintain line speed in the absence of line syncs?

Peter
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Old 14th May 2019, 10:10 am   #162
FERNSEH
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Default Re: Baird T5 restoration project.

The Baird 240/25 system sent only a single broad frame sync pulse so the possibility of hooking at the top of the picture was a real possibility if the line hold control was slightly off frequency. But there was no circuits to compensate for this.
The Cossor engineers also noted that the deep sync pulses limited the picture contrast. Baird sync pulses were 50 per cent of the video waveform, the reason for this was allow for the poor black level referencing which resulted in the picture information being present in the sync pulses.
It was a hopeless TV system with no potential for improvement.

And yet the Baird TV receivers were excellent.

DFWB.
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Old 21st May 2019, 7:52 pm   #163
FERNSEH
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Default Re: Baird T5 restoration project.

The old lacquer on the cabinet mirror lid surface has been removed to expose the condition of the veneers. Some minor corrective work is required but the veneer pattern isn't very nice. The book matching isn't perfect, but that's how it was made over eighty years ago.
Later today I'll rub on some French polish and then we'll see how the veneer really looks.

DFWB.
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Old 22nd May 2019, 10:07 am   #164
FERNSEH
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Default Re: Baird T5 restoration project.

Here's how the cabinet lid looks after French polish was dabbed on yesterday evening. It doesn't look too good. I'd suggest that the old veneer should be removed and replaced with something better.

DFWB.
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Old 27th May 2019, 6:34 pm   #165
beery
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Default Re: Baird T5 restoration project.

Quote:
Originally Posted by FERNSEH View Post
Here's how the cabinet lid looks after French polish was dabbed on yesterday evening. It doesn't look too good. I'd suggest that the old veneer should be removed and replaced with something better.

DFWB.
Hi David,
if the veneer is not damaged in any way, but just not very nice, then surely it would be best to keep it as it is the only original panel.
Mind you, if I was the original customer, paying 85 Guineas in 1937, I might be a little annoyed at the poor veneer matching, but then again, who would really look at the top of the lid...

Cheers
Andy
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Old 28th May 2019, 8:42 pm   #166
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Default Re: Baird T5 restoration project.

It would look better if the dark marks were first bleached out. And toner applied to the non-veneered sections.

Steve
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Old 28th May 2019, 9:25 pm   #167
Panrock
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Default Re: Baird T5 restoration project.

Also (sorry to be a pain) but it looks like patches of the old lacquer remain and more preparation is required.

Steve
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Old Yesterday, 11:01 am   #168
FERNSEH
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Default Re: Baird T5 restoration project.

It's evident some wee beastie has chewed the top of the line output transformer but I don't think all is lost because the damage is only the outer turns on what turns out to be the sync injection winding. See the attached circuit diagram.
The transformer has been removed from the chassis for inspection.
The primary is the inner winding, the secondary serves as the oscillator feedback winding and supplied the scanning coils.
The capacitors have been tested and all are useless. All the electrolytic capacitors are of TMC make and were fitted in 1947.

All the other chassis assemblies are working and just need the capacitors replacing or in the case of the waxies - restuffing. Most of the resistors are close to the indicated values.

DFWB.
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