Granada Television Brochure, 1970s
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1971 Beovision 3200
1971 Bush CTV1120
Granada Television Brochure, 1970s
Long Gone UK TV Shops
Memories of a Derwent Field Service Engineer
PYE Australia Circa 1971
Radios-TV VRAT
Fabulous Fablon
Thorn TX10 Chassis
Crusty-TV Museum, Analogue TV Network
Philips N1500 Warning!
Rumbelows
Thorn EMI Advertising
Thorn’s Guide to Servicing a VCR
Ferguson 3V24 De-Robed
Want to tell us a story?
Video Circuits V15 – Tripler Tester
Thorn Chassis Guide
Remove Teletext Lines & VCR Problems
Ceefax (Teletext)
Suggestions
Website Refresh
Colour TV Brochures
1970s Lounge Recreation
CrustyTV Vintage Television Museum
Linda Lovelace Experience
Humbars on a Sony KV2702
1972 Ultra 6713
D|E|R Service “The Best”
The one that got away
Technical information
The Line Output Stage
The map
Tales of a newly qualified young engineer.
Tales of a Radio Rentals Van Boy
Sanyo SMD
Disastrous Company Rebranding
1969 Philips G22K511
Memories Of The TV Trade
Crazy house
Dirty TV screens
Dual Standard and Single Standard CTV’s
Radios-TV on YouTube
The Winter of 62/63
A domestic audio installation
1979 Ferguson Videostar Deluxe 3V16
Music centre modifications
Unusual record player modification
B&K 467 Adapters
Mishaps In The Trade
1971 Beovision 3200
1971 Bush CTV1120
Tech Chat G11 at switch on bright picture
Hi all
my Philips G11 has a fault in that the picture brightness is varying. At initial switch on the picture is bright with black areas no longer dark. The picture is viewable and only noticeable on dark scenes. After 5 minutes or so the brightness returns to the setting it was at the last time it’s was switched off. I’ve tried everything, measured test points voltages from the brightness control on the decoder panel, HT check, with no fault found. The CRT is 100%. I’m guessing my next move should be to look at the CRT base panel components?
Check the voltages on the CRT, turn the colour off so all guns are using the same signal and check which voltages change from fault to normal condition. You may lucky and find the voltage rail feeding the A1’s in the CRT is varying and causing the problem. If it’s the cathode/grid voltages then work back from there.
I only ever saw one G11 so I’ve no experience with them but the reservoir/smoothing caps are notoriously poor and were upgraded, confirm you have the correct type or faulty ones can cause lots of damage, though probably nothing to do with this fault.
Frank
@stevesje71 There was a modification to the beam limiter circuit. It is decades since I did one but I remember removing the can of the module on the RGB panel and lifting one end of a diode from the print and soldering it onto the top of one of the resistors mounted on end. This was to cure random brightness 'jumping' on scene changes. It might be worth seeing if you can find details of the mod and seeing if it makes any difference.
Rich
Here's a link to the G11 beam limiter mod I posted on UKVRR a long time ago....
https://www.vintage-radio.net/forum/showthread.php?t=61374
Regards
Mike
Best regards
Mike
@nuvistor many thanks for this. I’ve already tried this, all voltages are stable. There’s a 12 reg even that which is prone to failure seems fine.
I’ve found the cause, the TBA560C luminance/chroma IC on the decoder panel.
thanks for your post
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