How to measure High tension of a FBT. . .

You could build a voltage divider, but to do it safely it would require more effort and cost than the probe.

Used units are out there ... ebay?

I think...

27KV requires a good isolation...

Uhmm...only the high voltage probe...very difficult to find for my Protek

608... I can search, probably, a full meter ...but I use it only this time.. probably, the cheapest solution is to ask help to an alectric laboratory.. I think that probably is the better solution, finally....

Starflex: Gosh.... I would forget about a dedicated, add on, HV probe for your Protek.... instead, get a stand alone high voltage probe with meter and ground clip... brand new around $60 - $70 from MCM and used ones are VERY very much cheaper on Ebay.... it appears that you have not tried an Ebay search yet??? .... or a google search yet???? .... Lots of stuff to look at regarding HV probes. And, as a very FIRST resort since you are on the SCI.ELECTRONICS.REPAIR newsgroup you should have FIRST gone to the REPAIRFAQS that discuss HV probes... safety, design and so on.... there is even a sample circuit there. I found this article in just a minute or two. Go to this link:

and the following two Ebay items in less than a minute: (I searched for "high voltage probe" ..... obviously)

If you can pick up a used Ebay HV Probe for just a few bucks it would most likely be much cheaper and much safer that building your own.

Best Regards,

Daniel Sofie Electronics Supply & Repair

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Go to the website for this newsgroup at

there, with a little search time you will find what you are looking for.

Also there are alot of cheap used high voltage probes on ebay all the time, many of them do not require a meter or scope to hook up to, they have their own meter built in, much handier and safer?

electricitym

Let's see... a piece of plastic pipe about two feet long... a hundred 1 meg resistors soldered in series... 100 megohms... one end connected to ground, the other to 27 kV... that's a current draw of only 270 microamps... and the voltage across the resistor connected to ground will be only 270 volts.

I found a probe on ebay, but in a pinch you can build one out of a bunch of 10 meg resistors in a piece of 1/2" PVC pipe filled with mineral oil. Shouldn't cost you more than 10 bucks to make.

Another option is to measure one of the other voltages produced by the flyback, usually there's several and they follow the HV pretty closely.

You need an HV probe or a stand alone HV meter for testing CRT high tension. You will not easily or feasibly be able to build your own. There are some very serious safety issues involved if you were to try to build your own. If you are going to be in the business of servicing TV sets and monitors, then you will have to buy the necessary tools to do the job.

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JANA _____

I would be very leery about the accuracy of a probe bought on Ebay. The voltage divider resistors in these probes are very fragile, sort of a glasslike construction. If the probe gets dropped, or banged the resistors can get hairline cracks, and the readings will be way off.

spam wrote in news: snipped-for-privacy@corp.supernews.com:

Too much load. The Fluke HV probe is 1000 Megohms,rated to 50KV,IIRC.

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Jim Yanik
jyanik
at
kua.net

Sofie wrote: [snip]

Hi Sofie, and many thanks for your reply. Before searching in Google, I prefer to ask to a "real man" if it is safety or not: this is "my first monitor" and I'm not very sure of what I can do or not. I have already search on Ebay about High Voltage meter, about two weeks ago... Yes, the price that I can find -especially for used item- is very low...but I live in Italy..and there is the shipping cost!! :-) Consider that, if i choose an economical shipping, it cost about 20 dollars..and it requires VERY OFTEN three months (!!). In the better chance, it arrive in "only" 8 weeks. If I choose, instead, a faster shipping, the cost is higher...40 dollars. So, the total cost is quite high, for a item that probably I'll use once in my life..! I'm not a "repair man", I don't work in a laburatory: I'm only a student, of course, with the passion for those things..but only a passion...and the CRT's monitor are almost dead... Thank you for the link about the FAQ's: I don't know that this newsgroup had the faq's...! So, finally...thank you for your reply, and sorry for the "stupid" question!

...some sellers don't sent to Italy, or the shipping cost is too high, if I want to receive it in a resonable time.... :-(

I had seen many items, but I have a doubt..and I've found a seller that can ship it to Italy for only 25 $, S&H included. I had seen that all the items included the meter (probably, a galvanometer), but it is quite little. I think that is very difficult to read a valour of 27kV, +- 0,1 kv. Is only my imprerssion, or it is really correct..?

It is no harder to read 27 kv on a meter than to read any voltage on any other meter. Usualy around 27 kv would be in the most accurate area of the meter. But, it would be good to test the meter against a known voltage. We used to have 4 or 5 of these, but kept one locked up as a standard to check against.