Motorola ts907 low hv

[Electronic M]

Originally Posted by Yamamaya42

I would be happy with any type of Electrostatic deflection type TV to play with, however, the pilot TV 37 is a bit small, it does not stop some putz from asking $1000 for one on greed bay.

I almost never buy from eBay because they're almost always overpriced by stupid amounts.
I've had 2 TV-37 and I think the most expensive cost me $125. Look for them at radio swapmeets they almost never exceed $300 there even when they're mint and have all the accessories.

[timmy]

What exactly is the video peaking pot for in the rear of the set I don’t see any change in the video when turned

[Yamamaya42]

To quote Electronic M, it acts like a tone control for video, and has a very subtle effect on the picture, you won't see it unless you have everything working well and clear and correctly adjusted.

[timmy]

Well now the original flyback is bad started blooming and a smell and the donut is so hot can’t touch it. One thing after another

[Yamamaya42]

That makes little sense, as it seems to have been OK for quite some time, something has to have triggered it like a failed HV rectifier/ regulator or related circuitry, gonna have to wait for the FBT to cool all the way down, and do a full resistance check... yet again on it before you condemn it.

[timmy]

I bought the last flyback for this tv that I know of and it is new but so old all the wax that coats the donut came completely off clean I’m wondering if I should coat it with silicone.

[Yamamaya42]

IF the FBT is OK to start with, then something like. MG Chemicals 4228-55ML Red Insulating Varnish. very messy, but works.

http://suzaku.live-evil.org/0716221404.jpg

http://suzaku.live-evil.org/0717222342.jpg
http://suzaku.live-evil.org/0719221857.jpg

how i saved the FBT on my Coffman colorcaster .

[timmy]

This flyback is new never used but may have been stored in sunlight heat the donut has nothing on it the wax got hard and peeled right off. Silicone is messy as well but it should protect it.

[Yamamaya42]

Corona dope has a very high dielectric factor, and can easily get into the deeper layers as it's a liquid, and can be put on in layers. it was made for HV applications.

[timmy]

Looks like there’s a short in the donut checked the rectifier hv regulator both ok and brightness down set to 24 kv brightness up hv drops to 20 kv and donut gets hot so it’s done. This flyback is 57 years old and besides they usually don’t let you low there are going bad afterall they can just short and that’s it.

[Yamamaya42]

Well, if you don't get about 600 ohms from the caps of the horizontal output tubes to the cap of the HV regulator tube, then that is a sign it's toast, otherwise, it may be something else if it is 600.

[timmy]

Well it measured well below 600 IIRC it was around 580

[Electronic M]

Originally Posted by timmy

Well it measured well below 600 IIRC it was around 580

That's within 4% which I consider to be within a reasonable margin of error for a part to be considered good.

You really need to do a ring test to find shorted turns when it's that close.

[timmy]

Originally Posted by Electronic M

That's within 4% which I consider to be within a reasonable margin of error for a part to be considered good.

You really need to do a ring test to find shorted turns when it's that close.

It’s got to be shorted because it gets hot rather quickly and if I lower brightness alittle the hv comes up

[Yamamaya42]

It could be regulator failure, or like what I had, burned out to ground heater windings to the HV rectifier.

Found it by pulling the cap off the rectifier, and saw I had a strong AC arc to ground, that was lost when plugged onto the rectifier tube, at any rate, what we are getting at, it's a bit too soon to say the FBT is bad yet.