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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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25th Jan 2019, 10:51 pm | #1 |
Pentode
Join Date: Oct 2005
Location: Barnet, London, UK.
Posts: 167
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BRC 2000 Pincushion correction Marconi 4701 (FERNSEH CIRCUIT)
Hi David I am restoring a BRC 2000 Marconi 4701 it seems shame that the components for the pincushion correction have not been fitted when it was made. The board had been made to take them.
I used a AT4041/37 Transductor and a coil type AT4040/50. It is only working on 625 lines at present. Thank you for the circuit. Keith |
25th Jan 2019, 10:59 pm | #2 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,424
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Re: BRC 2000 Pincushion correction Marconi 4701 (FERNSEH CIRCUIT)
Was the reason for having the CRT “ upside down” so that the distortion was not as noticeable. Reports have it that Thorn lost money on every 2000 they made so I suppose penny pinching was going to occur.
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Frank |
25th Jan 2019, 11:07 pm | #3 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: BRC 2000 Pincushion correction Marconi 4701 (FERNSEH CIRCUIT)
Hi Keith, that's much better picture geometry. Nevertheless, BRC did the same with the 3000 series CTVs, no pin cushion correction.
In 1971 the company realised they had to fit the 22" and 26" square corner CRTs which necessitated a pin cushion correction circuit introduced on the new and much larger convergence board. DFWB. Last edited by FERNSEH; 25th Jan 2019 at 11:18 pm. |
25th Jan 2019, 11:26 pm | #4 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,557
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Re: BRC 2000 Pincushion correction Marconi 4701 (FERNSEH CIRCUIT)
Hi.
There was a good article in Television magazine by Keith Cummins which described adding raster correction to the BRC 2000. It was in the August 1978 issue and can be found here https://www.americanradiohistory.com...UK-1978-08.pdf Regards Symon |
25th Jan 2019, 11:34 pm | #5 |
Heptode
Join Date: Jun 2007
Location: Durham, County Durham, UK.
Posts: 640
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Re: BRC 2000 Pincushion correction Marconi 4701 (FERNSEH CIRCUIT)
There was an A56-120X 22" model released without pincushion correction. This was fitted with the 8500 chassis and was available through rental outlets only. Model 5723, dreadful set.
There were 22" models in the 3000 chassis range with no correction but they used the rounded corner A55-14X. John. |
25th Jan 2019, 11:42 pm | #6 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,557
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Re: BRC 2000 Pincushion correction Marconi 4701 (FERNSEH CIRCUIT)
Hi
I remember there was a 8800 chassis that was used with the 22" CRT. I only came across 19" 8500s which weren't too bad to service and were reasonably reliable. Regards Symon. |