Changing LOPT in monitor...

Ignoring shipping charges, just to bench a monitor is $60 and up...rather close to the cost of a replacement. I have been an electronic technician for over 40 years, and never heard of a "LOPT". Housesomever, the way to render the HV on the CRT safe, is to first connect a wire to the chassis and/or the bare wire running around the outside of the tube (it is contacting the black aquadag on the outer surface). Make sure it cannot become disconnected. Then poke the other end (bare wire here) under the HV cap at the CRT (anode). Tape it down to the pix tube if you like, to ensure it will not fall out or be pulled out.

Do your work.

Remove that wire fromthe CRT anode first, and then from the chassis/ground wire mentioned.

You do monitor repairs, and have never heard of a ine utut ransformer??

Mmmmm.

Robert Baer wrote:

Line Out Pput (Power) Transformer ?? Another reference to the Flyback, Integrated High Voltage Transformer, High Voltage Transformer, Et Al Fin. The terminology, I believe, initially was used in Europe (British Isles ??), and has been used internationally for quite a period of time. I've been involved in Consumer Electronic Device Repairs since the early

For your safety, send the monitor out for service, to do any work in it. After changing the flyback, there are a number of safety and operation tests to do. You will not have access to the necessary equipment at home for this. It takes more than a simple DVM to work on these.

There are issues for testing and adjusting the HV at the anode, testing the hold down current and HV safety cut-off, testing the performance of the main power supply, and etc. There is then the set-up of the CRT screen voltage, and the beam focus set-up.

If the HV is too high, there is risk of X-Ray radiation exposure. Some people tend to smirk at this one, but if you venture in to the safety issues concerning CRT monitors, this is a very serious thing.

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I know a bit about low voltage stuff, but I want to change the LOPT in an Eizo/Nanao monitor.

I know the LOPT is faulty, as it arcs and pops when the monitor is running, and after much effort, I've found a spare.

The monitor (an excellent F77) is probably not worth sending to a professional to replace the LOPT as the s/h value is probably only USD

100-200...

What do I need to know about safety in order to change the LOPT? It's certainly worth trying to repair as the picture quality is excellent, but not worth dying for !

How do I ensure that there is no HV left in the chassis/tube before starting work - the monitor has not been powered up for some time (month or so) at the moment.

What special tools (if any) will I need?

I really don't like really HV stuff much (very healthy respect) and would appreciate the advice...

Thanks from a slightly paranoid Mike...

I had never heard it called that, either. I still don't know what it means. Do you mean what we call "power transformer" (which takes the incoming AC from the line)?

running,

Alright already! Over here, a LOPT = Line Output Transformer = Flyback Transformer = FBT

Paranoid Mike

means.

No. The 'line output transformer', operates from the horizontal deflection 'line' drive, in flyback mode, with a voltage multiplier, to generate the main HT voltage for the tube (hence 'line', and 'output'). As has been said, changing this, involves resetting most of the high voltage adjustments around the tube, and implies having th correct manual with the voltages/tests required, and a suitable high voltage probe for the testmeter/scope.

Best Wishes

And you actually believe that all professional servicers or even most do these tests? Geez!

I do agree that in this case where arcing was the original symptom, at least a test of the HV after repair should be made to assure that it isn't excessive.

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I do know what a line output transformer is, and most places *and functions ) where they may be used: 1) audio work - mostly Public Address (PA) systems; 2) the term sometimes is loosely used in RF power and/or distribution amplifiers; 3) again more loosely used for transformers in Ethernet and similar communications work. However, of the many hundreds of computer monitors i have seen, *NOT ONE* had any such thing and none of them could possibly use such a thing. Perhaps you are referring to either (1) the power transformer (from the incoming power line) - if it had one of them at all; OR (2) the

*flyback* transformer.

And, like i said, it costs $60 or more, just to "bench" them; and a replacement would not cost a lot more...

In article , Robert Baer writes

Line Output Transformer, pronounced "loptie".

It's what monitor techies in the UK call a flyback transformer. Strictly speaking, I think the word 'flyback' is more correct, since these transformers operate on the flyback principle.

The term 'Line output' comes from the earlier days of TV sets, when a conventional transformer was used to boost the horiz pulse to about 9kV, which was then amplified by a tripler module to produce the final anode voltage.

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