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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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19th Dec 2019, 9:19 pm | #21 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Newbie to Televisions working on GEC BT320
Circuit diagram of the IF, video and audio board.
DFWB. |
20th Dec 2019, 10:27 am | #22 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: Newbie to Televisions working on GEC BT320
From your picture the black line looks more like a telegraph wire. You will probably find it is oscillation in the frame output valve N379. The Mullard equivalent is I believe a PL84.
The scan coils will require a slight adjustment to square up the picture. |
20th Dec 2019, 11:58 am | #23 | |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: Newbie to Televisions working on GEC BT320
Quote:
It still didn't stop my enjoyment of Hancock last night though |
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20th Dec 2019, 12:00 pm | #24 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: Newbie to Televisions working on GEC BT320
Thanks for that, I have two circuits for this set, both have the correct components, or so it seem's, but the numbering is incorrect on both of them.
I guess with such a long production run of this model, it went through various changes. |
20th Dec 2019, 2:28 pm | #25 | |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: Newbie to Televisions working on GEC BT320
Quote:
A replacement PL84, has cured it though. It must have been self oscillating, I've not come across that before. |
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20th Dec 2019, 2:34 pm | #26 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: Newbie to Televisions working on GEC BT320
The tuner would cause a blank screen if the knob was touched and I wanted to check for Hunts capacitors in there.
I pulled off the cover and a little roller fell out, I cant see where it goes. The tuner does not give the reassuring clunk as it's turn now. I can see a Hunts capacitor, but I'm now nervous removing the biscuit assembly. If I release the springs on each end of the spindle will the assembly just drop out? I still have what I pressume is Video on Audio, A loud raspy buzz. There is also not a great deal of audio. I thought the set had not been touched as there was no evidence of any replacements, but while replace them myself, it appears quite a few of the slugs are cracked, so the alignment could be way out. I've only ran it up on a variac so far, and watch the H.T. on a voltmeter as I wind it up. I would imagine the H.T. would rise to over 300v if it's just "Plugged in" the caps are all rated to 400v, so that not a problem, but the supply cap is a 275v component, Am I worrying needlessly ? Nick Last edited by NickG0HIK; 20th Dec 2019 at 2:58 pm. |
20th Dec 2019, 7:41 pm | #27 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Newbie to Televisions working on GEC BT320
The attachment shows the channel indexing spring and roller on the side of a similar tuner fitted in the Ferguson 454T.
That 275volt capacitor, is it an AC rating? DFWB. |
20th Dec 2019, 8:17 pm | #28 | |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: Newbie to Televisions working on GEC BT320
Quote:
I found the intermittent was caused by the I.F. coax centre had come adrift. As the markings had come off the channel selector, I have made a note of the biscuits, it looks to be a standard universal. 1,9,2,10,3,5,11,8,5. The Supply cap says 275 v DC & 275 DC surge. |
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