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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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24th Aug 2011, 10:26 am | #21 |
Hexode
Join Date: Feb 2011
Location: Gloucestershire, UK.
Posts: 376
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Re: Bush TV12 restoration.
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24th Aug 2011, 10:31 am | #22 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
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Re: Bush TV12 restoration.
Don't worry about the transformer if it is O/C. Virtually any frame blocking transformer will work perfectly well in a TV22 even ones with wildly different ohmic values.
__________________
Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
24th Aug 2011, 11:38 am | #23 |
Hexode
Join Date: Feb 2011
Location: Gloucestershire, UK.
Posts: 376
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Re: Bush TV12 restoration.
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24th Aug 2011, 12:31 pm | #24 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Bush TV12 restoration.
Things are not going well. It is likely that the lack of width problem is the line output transformer.
The TV12 along with earlier models such as the TV1,TV2 and TV11 employ two transformers in the line output stage. One does the flyback EHT and the other the scanning. It seems that the line scan transformer has failed. The boost and scan coil series capacitor have been replaced. The valves are OK. DFWB. |
24th Aug 2011, 12:45 pm | #25 | |
Hexode
Join Date: Feb 2011
Location: Gloucestershire, UK.
Posts: 376
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Re: Bush TV12 restoration.
Quote:
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24th Aug 2011, 1:16 pm | #26 | |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Bush TV12 restoration.
Quote:
The suspect transformer is does not use the flyback pulse in operation. It acts in a similar manner as an audio transformer except it must operate at 10Kc/s up to 100Kc/s. DFWB. |
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24th Aug 2011, 6:13 pm | #27 |
Hexode
Join Date: Feb 2011
Location: Gloucestershire, UK.
Posts: 376
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Re: Bush TV12 restoration.
Frame wasn't running because R53 was as near to open as can be.
Aftyer some gentle persuasion , I have a picture. Brightness control is open circuit at one end , the contrast control is scratchy and I'm yet to go through the waxy's on the RF deck, but ... it is getting there .... |
25th Aug 2011, 8:55 pm | #28 |
Hexode
Join Date: Feb 2011
Location: Gloucestershire, UK.
Posts: 376
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Re: Bush TV12 restoration.
I couldn't get the first anode voltage right. I'd missed the cap decoupling the metrosil, hidden under the tag strip. A few more caps and I should be done. Got plenty of contrast now and the tube's lovely and sharp. Linearity is not good as yet.
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2nd Sep 2011, 8:59 pm | #29 |
Retired Dormant Member
Join Date: Oct 2007
Location: Leicester, UK.
Posts: 809
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Re: Bush TV12 restoration.
You could do with another set to try a swap. The tube does look pretty bright in the photo!
Brian |
2nd Sep 2011, 9:07 pm | #30 |
Hexode
Join Date: Jan 2007
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 453
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Re: Bush TV12 restoration.
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4th Sep 2011, 7:43 pm | #31 |
Hexode
Join Date: Feb 2011
Location: Gloucestershire, UK.
Posts: 376
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Re: Bush TV12 restoration.
Thanks Dave. I knew it rang a bell somewhere...
Any update on the TV12 FERNSEH? |
6th Sep 2011, 10:46 am | #32 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Bush TV12 restoration.
Hi Andy,
The line scan transformer is definitely suspect. I will be out of this shop for quite some time so no restorations will be done in the near future. There's plenty of jobs to do when I return. DFWB. |