Motorola ts907 low hv

[timmy]

Flyback should be ok because it is making 640v and 770v so where is something crossed. Omg this set wow.

[timmy]

Without warm up just when screen lights up the 640v is 605v and the 770v is 760v didn’t check ohms yet but this looks ok I tested at the 10k and 47k.

[timmy]

Could the horizontal frequency be off in such a way that it would generate higher voltages and still be able to lock into video.

[Yamamaya42]

Not likely, if the horizontal frequency was off, then there would be no video lock, horizontal AFC and sync control will bring it into range for it to lock into the incoming video, but it has to be within the right frequency range in the first place to do so.

Something else is going on here, at this point, you may try to unhook one side of C96 to see if that has any change on the heating of the coil.
Can't think of anything else right now. :O

[timmy]

None of this makes sense one leg off c96 coil gets hot I don’t know where this coil could be getting a ground to heat up like this. It can’t possibly be designed this way that it would get this hot and I believe this may have something to do with the video in some way or another.

[Yamamaya42]

if you have not already, make sure R145 is still = 100K OHMS.

[timmy]

Originally Posted by Yamamaya42

if you have not already, make sure R145 is still = 100K OHMS.

Yes checked r145 it’s still good so I’m thinking maybe overall this coil is supposed to get hot can’t see any other reason it’s getting hot it’s hard to believe that the coil stayed in it’s holder all these years with some kind of antique glue they used and now it’s falling out. I’m probably going to remove it and use hi temp silicone maybe it will stay in this time. If it burns well then i know that it’s 35ohms and 3600uh and hope I could find another if I need it.

[timmy]

This is L42 the coil itself is big compared to others in this tv.

[Yamamaya42]

The coils still look OK.

This is a bit costly, but should work.

Find a ceramic heat sink NOT metal, that can be glued to the coil, big enough to do it some good, small enough to fit under the chassis, use thermal conductive epoxy to stick it together, making sure the epoxy touches both the coil and heat sink.

Once cured, it should run cooler.
https://www.amazon.com/MG-Chemicals-...Q%3D%3D&sr=8-3

example
https://www.walmart.com/ip/Whigetiy-...erId=101180981

[timmy]

There is absolutely no room for anything other then the coil lol �� I have 500 degree silicone.

[Yamamaya42]

Originally Posted by timmy

There is absolutely no room for anything other then the coil lol �� I have 500 degree silicone.

you can get a small ceramic heat sink

[timmy]

Problem now is the coil measures 55ohms it’s not 35 ohms anymore so I guess it’s not supposed to get this hot more heat more ohms.

[timmy]

I have a Motorola book with a schematic note the500vpp pulse negative and positive where do these come and go.

[timmy]

Better picture. I had taken the focus coil out to change the horizontal centering pot but I took a picture of the coil so I wouldn’t put it back wrong so I know by the color of the wires it’s right. I can’t for the life of me find C3-C power supply cap I’m just checking if I maybe hooked it to the wrong source.

[Yamamaya42]

https://www.amazon.com/Ceramic-Cooli.../dp/B07VH3F9SQ 1/2 inch in size should fit nicely any replacement coil will be unobtainium, protect what you have while it still works, put a ceramic heat sink on it.