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

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Old 1st Nov 2016, 9:04 pm   #21
FERNSEH
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Default Re: Preparing a TV set for November the 2nd.

Hi John,
With regard to the Cossor, apart from the picture shift fault there is two more problems to sort out. The CRT is stuck fast to the vulcanite mask, great care will be required to release it. The second fault is the 0.05microfarad capacitor which connects the control grid of the CRT to the anode of the video amplifier needs replacing, Cossor calls the video amplifier the intensifier stage. Remember the CRT grid and cathode are at EHT potential so a +5000 volt capacitor is needed as the replacement.

The HMV also needs work to return it to working order. The HT supply voltage is very low, surely that shouldn't be a difficult fix?

DFWB.
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Old 2nd Nov 2016, 2:37 am   #22
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Default Re: Preparing a TV set for November the 2nd.

Good results at last. The receiver and timebase supplies were delivering very low HT volts. The fault was easily solved by replacing the smoothing capacitor, the reservoir capacitor was found to be OK. The attachment shows the bad capacitor.
The electrical repair was easy but gaining access to the power unit wasn't. The 900 receiving attention is a very early production model. The cabinet is slightly smaller than other HMV 900 models and because of this fact the power unit is a very difficult unit to remove from the cabinet.
The CRT is good and gets better the longer the set is switched on.

Note the serial number plate, the set is described as a machine.

DFWB.
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Old 2nd Nov 2016, 9:27 am   #23
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Default Re: Preparing a TV set for November the 2nd.

Hi David,

That's great, just in time for today's celebrations.

BTW I have fuund that the TCC elctrolytics with the orange letters printed on a clear wrapper were amongst those used by EMI in their post war repairs, although the electrolytics used in the earliest post war overhauls were made of cylindrical waxed yellow card with black vulcanised ends.

Are they the caps that were in the set when you obtained it? Do you think the TCC caps represent a second repair by EMI or is it that it took a long time to get through all the overhauls, during which time they changed their capacitors to more modern ones?

Cheers
Andy
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Old 2nd Nov 2016, 12:29 pm   #24
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Default Re: Preparing a TV set for November the 2nd.

Hi Andy,
Those TCC electrolytic capacitors were supplied or fitted by EMI service after WWII. Were these huge sets returned to the companies' service department or was the recommissioning work done by the local HMV dealers service personnel?
In fact if one considers that these TCC capacitors were parts supplied by the EMI service department it might be a good idea to restuff them with new capacitors in order to retain the original 1946 appearance.

DFWB.
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Old 2nd Nov 2016, 3:44 pm   #25
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Default Re: Preparing a TV set for November the 2nd.

BBC then featured on BBC now: http://www.bbc.co.uk/news/entertainment-arts-15551270
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Old 2nd Nov 2016, 7:53 pm   #26
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Default Re: Preparing a TV set for November the 2nd.

Well it had to be done. My HMV 900 has not been switched on for a while. Surprisingly it warmed up quickly but the delicate tube took around 15 mins to give a really good picture.
The film is actually the post war demonstration film [1946]
The 900 has not been recapped. The EHT transformer was rewound in 1973 and a couple of caps replaced in the frame timebase. The Emiscope 6/6 tube looks original.
A minutes silence would be in order for the EMI team that gave us the World's
first regular television service. John.
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Old 2nd Nov 2016, 7:54 pm   #27
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Default Re: Preparing a TV set for November the 2nd.

Another picture from the 900.
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Old 2nd Nov 2016, 8:50 pm   #28
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Default Re: Preparing a TV set for November the 2nd.

Really living in the past John, even your year planner is last year Lovely to see these early sets still run.
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Old 2nd Nov 2016, 9:08 pm   #29
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Default Re: Preparing a TV set for November the 2nd.

Ha! ha! Nigel. Yes it is last years still in place.
Before I replaced my ink gobbling printer with an Ecotank I used to refill my own cartridges.
I had a 'blow back' that sent a jet of black ink over the wall!
Due to shelving etc it is just too difficult to repaint.. I will one day for sure.
The old year planners [there are four under that one]cover it just fine. Out of sight, out of mind.
Glad you like the pictures.
I hauled my neighbour in to see it working. He has been following the programs all day. He could not believe it and was totally amazed. John.
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Old 2nd Nov 2016, 9:31 pm   #30
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Default Re: Preparing a TV set for November the 2nd.

Hi John,
excellent results from your 900. Like yours mine has had very few component replacements, most notable is the EHT transformer.

Restoration work on the Cossor 137T will continue.

DFWB.
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Old 3rd Nov 2016, 1:35 pm   #31
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Default Re: Preparing a TV set for November the 2nd.

I'm out of the country at the moment and unfortunately missing the magic date but it's great to see that you guys are celebrating it in style.
Peter
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