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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 4th Dec 2017, 6:54 pm   #21
Clydeuk
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Join Date: Mar 2012
Location: Liverpool, Merseyside, UK.
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Default Re: What are the chances of a modern LOPT failing?

I have an abiding memory of late 80's and 90's Panasonic sets with LOPTX failure. Can't remember the chassis but it was more than one type, and you needed a mortgage to buy a replacement, meaning the set was always a write-off as far as the customer was concerned.

There was also a cheap 14 inch Binatone portable of which I saw many examples, but never saw one working because the LOPTX was always gone, and it was either not available or very expensive.
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Old 4th Dec 2017, 7:43 pm   #22
TonyDuell
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Default Re: What are the chances of a modern LOPT failing?

I've certainly had modern-ish line output transformers fail, not always in obvious ways. I had one go in an Amstrad monitor, the fault was in the thick film resistor unit used to set the focus and first anode voltages, with the result that these drifted as the thing warmed up. Back then (this was 25 years ago) I could get a genuine replaement from (I think) CPC. Not cheap though.

I've replaced many line output transformers (well the manual called them 'flyback transformers, but that's the American term) in DEC terminals. VT100s etc would eat transformers if some of the diodes or capacitors on the video board went leaky, which they did with monotonous regularity. VT220s were better, but the VT3xx series had major line output issues in my experience. No idea what I'd do if I needed one now...

The fact that Konig, HR Dieman, etc sold 'copies' of the line output transformers for popular TVs and monitors would suggest there was a market for them. And thus that said
transformers did fail.
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Old 4th Dec 2017, 7:55 pm   #23
Welsh Anorak
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Default Re: What are the chances of a modern LOPT failing?

There was a batch of Panasonic transformers with the odd A1 connector on the top that failed, though Konig soon had a reasonably priced replacement available which looked identical to the original.
CPC saw a market in the replacement LOPT market and asked for working examples of transformers to copy them. Oh dear. Their transformers were hopeless - they either didn't work at all (Philips 8833) with pins shorted or else gave wildly incorrect EHT and heater voltages. They soon were withdrawn and we went back to the jolly yellow boxes.
Glyn
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Old 4th Dec 2017, 9:42 pm   #24
Lloyd 1985
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Default Re: What are the chances of a modern LOPT failing?

In my messing about with modern telly' from the tip days, I had a few duff LOPT's, the little Vestel 14" portables badged Bush or Alba seemed to have problems, I had 2 (actually still got one!) where EHT would arc out of the transformer to the core, or as it preferred, my fingers if they got anywhere near! The set usually shut down instantly or at least very soon after trying to turn it on, normally with one or two loud snaps! I bodged the one I still have with araldite, which worked but you could still hear some crackling going on and the occasional loud snap followed by the set shutting down. I should really try and get a new Lopty for it one day.. Grandata did sell a replacement, but I never got round to ordering it. I also had a Daewoo portable go the same way, I remember fitting a new horizontal output transistor and powering up only to watch the Lopty arc violently and blow the transistor again.

I have a Roadstar 10" portable that had a duff transformer too, it had melted on the side and split open, must have been shorted, the set still powered up but the line whistle was quiet and no picture would appear, the transistor was ok but got hot very quickly.

All the replacements I did buy were the yellow box HR ones, never had any problems with them

Regards,
Lloyd
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