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CTV Latest Project Rediffusion MK 3 and question

Colour Television

Last Post by mfd70 1 month ago

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mfd70

(@mfd70)

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I've recently got hold of a Rediffusion Mk3 Television, model CH5130, it came from Lucien Nunes collection and was delivered to Cardiff by a helpful chap called Steve, I don't know if he posts one here. It's not a pristine example but I'm happy with it, I've tested the tube and it looks OK. Now I've fixed a couple of these in the past and this one has the same problem, one of the line scan thyristors is shorted. But here is the problem, I removed the line scan board and the label says it is for 22" and 26" tubes, does anyone know if the board can be modified for 20" sets, (maybe this one already has) is the same LOPT used and how to tell ? I know the later Mk4 had the same bare PCB but so many different and extra components they could not be sensibly modified.

I do hope I can get this one to work, I think I have some of the ITR thyristors here somewhere

Posted : 07/11/2024 9:36 pm

malcscott

(@malcscott)

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The 22/26 line scan pcb is not interchangable with the 20 inch. LOPTX, input inductor, commutating coil and various other caps are different. Tripler failure was a common cause of faulty lop thyristors.

Posted : 07/11/2024 10:14 pm

slidertogrid

(@slidertogrid)

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The set has probably been through one of the ex-rental sell off places. I say this as it has been sprayed black. This was common practice with the older sets the places sold off. They were usually showing their age, scratched and teak when customers wanted 'black ash'.

There was a local place selling them for about £30/£50 for a 10 year old set painted black and just about working. If that is the case the panel was probably swapped then. These places would have huge piles of grotty sets and a few "engineers" smoking fags boosting tubes and swapping panels. They knew all the bodges and dodges!

Nice to see another of Lucian's sets in good hands! Stuart and Steve really tried to find good homes for everything they could.

Posted : 07/11/2024 11:12 pm

malcscott

(@malcscott)

Posts: 1617

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If this set has the model number CH5103 it is a cable set converted to aerial. CH was cable sets id, this set should be a CU5130. The crt in this set will be an Hitachi which i have never known one to fail. Later crt,s were produced in Finland by Hitachi under the Finvalvo label.

Posted : 07/11/2024 11:49 pm

mfd70

(@mfd70)

Posts: 293

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Topic starter

Thanks for the (quick!) replies ! The set has been converted to Cable / Aerial operation, new signals panel and button unit, I'd like to restore it to HF, but if it has the wrong line scan panel, I'm bit stumped ! I'll a replacement thyristor and see what happens.

The cabinet has not been painted black but has a vinyl type covering, it has certainly come from Granada TV rentals as there is a blue sticker with the granada code, but this has worn off.

Posted : 08/11/2024 12:08 am