Motorola ts907 low hv

[Yamamaya42]

Originally Posted by timmy

How can I stop the blue arc that is between the rectifier and the 2 wires for the 3 volt heater

inducted corona, mostly harmless, my hoffman colorcaster did the same thing, just keep the wires as far away from the tube as you can, I did this by cutting the bottom off an old pill bottle and putting it around the tube as a guide/form to keep the wires away from the tube.

[timmy]

Thought it may break the glass on the tube. Smell of corona is not bad it cleans the air.

[Yamamaya42]

Again, don't take the voltages listed in the SAMs as gospel, expect them to differ by some degree.
Your screen showing good video with direct input is a indication that power is stable.

As for the hot diodes, this is not suprising, they are under heavy load, but if there is doubt, replace.

As suggested before, these are cheap and much better than the OEM ones.

https://www.mouser.com/ProductDetail...2B4kkscA%3D%3D

[timmy]

With video injected the horizontal and vertical are good stable picture but I can’t imagine where the stray voltage could be coming from because obviously it’s still pulling the voltage down but it seems not all the time or even where to start to look. There is a 390 ohm resistor to ground I clipped it and it measures 390k the voltages are low in v1 v2 but if I leave the resistor off the voltages jump up.

[Yamamaya42]

My set has a 3A3-C, and the heater wires were getting a bit close and causing a blue glow, all I did was use a plastic spacer around the tube that was about 10-15% larger than it's diameter to keep the wires away, it's working perfectly.

[timmy]

Problem I have is I only have a 360ohm resistor not a 390ohm. I could try it see what happens.

[Yamamaya42]

R47? I guess you missed that when you checked resistors in the area before, but I did mention that the ones off the cathodes are the ones most likely to be bad for some reason.

[timmy]

Yes r47 is it me orange. Blue. Brown is 360 ohm correct? I don’t have a 390 but this meter just yesterday measured 360 ohm and the 390 in the set measured 390k .

[Yamamaya42]

360 is close enough to try, but do take a look at the markings on what is coming out, just to be sure there is not a production change.

[timmy]

390ohm is what’s in there 360ohm made no difference v1 v2 pin8 should be 100v but 60v on v1 and 55v on v2

[Yamamaya42]

the 6EH7s are new? & what was the voltage on pin 7 V 1 & 2 ?

[timmy]

I was thinking Matthew antenna input is not making it to the first IF because of a bad trap it supposed to measure 15k but it’s a 2 connection and to measure it I would think it would have to be turned and if I do that I couldn’t get it back.

[Yamamaya42]

I was thinking of a “worst case scenario”, but not being able to see and test it, there is no way to know.

This may be a case of the dreaded “silver mica disease” bad caps in the coils L4 L5, causing wrong voltages on pins 7 & 8, if true, then hopes of getting it working is very low.

[timmy]

6eh7 all new 2 sets v1 pin 2 7v v2 12v v3 pin 2 0

[Yamamaya42]

Originally Posted by timmy

6eh7 all new 2 sets v1 pin 2 7v v2 12v v3 pin 2 0

the important voltage is pins 7 & 8 on the 6eh7 tubes.