Forum Free Registration Closed
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
Forum Free Registration Closed
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
What's wrong with this TV?
This is an Australian HMV from 1956 (625 line) displaying a PM5544 test pattern via a modulator, i.e. through the tuner. Obviously the VIF alignment is OK!
The yoke is a 70 degree UK-made part, probably sourced from EMI, and it has a variable trimmer to adjust for crosstalk.
Look at the "scallops" on the LHS. What do you think?
There appears to be some vertical shading in line with the scallops, ringing somewhere in the line scanning, I found it usually in the line linearity coil, damping resistor open circuit but could be in the scan coils.
That’s a good a guess has I have.
Frank
Yes I thought it would have something to do with the linearity coil or the boost diode. But everything checked out OK. It got worse with increased width.
Anyway, to rule out the scan coils I checked the inductance of both H windings and found a 25% difference. Stripping it down I found that one of the ferrite "stator" discs was broken, on guess which side?!
So I have araldited it together and clamped it. Let's see how that works out.
Should be OK, see how it is when back together.
It’s the sort of fault most customers would not notice.
Frank
I was thinking it may be ringing, then Frank mentioned open circuit damping resistor. I guess a broken yoke would give much the same effect, if you consider two resonant pieces where there used to be one, both 'jiving' at different resonant frequencies.
I remember an early '60s EKCO my granddad brought in, showing very similar effects. In the end, it became my bedroom set for several years.
Well, gluing the ferrite back together improved things enough to allow it to be returned to its owner. Any width setting beyond what will fill the screen results in foldover about 1/3 of the way across as the core saturates, my guess. But the wrinkles are gone.
Here's a shot of the yoke before I dismantled it, the chassis (except for the mains transformer and the pair of 6N3s does it look familiar?) and the finished result ready for its owner. That rebuilt CRT is VERY bright!
And the picture that should have been in the post above....
An excellent repair, can’t recognise the chassis but I didn’t see many HMV sets.
Frank
- 33 Forums
- 7,942 Topics
- 116.3 K Posts
- 6 Online
- 331 Members