This is what I made for the ballast. I didn't mount the CL90 at the top like Bob did but it does match his hand drawn schematic

Well I’ll tell ya that sucker gets really hot

I actually considered installing a small fan on the chassis. Maybe I'll do that anyway.

Tim is having issues with posting so he sent me this...one of the coils in the video circuit. There are 2 in the detector and 2 after the video amp tube so I'm not sure which one this is. I checked continuity on the 2 outside the detector can and they ohmed out good but...that's why I shipped it to him!!!

One of the coils in the detector can! That's where video was getting stopped!

You definitely should not be needing to install a fan. The whole TV only consumes 100 watts. The diode ballast should be less warm than one of the 25L6s in the TV.

In other words, if implemented correctly, using the ballast that Bandersen designed in a healthy Moto VT-71, it should NOT be getting volcano level hot unless there is something really wrong?

Got a whole lot going on with this moto. Going over the vertical because it appears the picture is being torn from the side and it’s very unstable looks like it’s fighting against vertical and horizontal.

Or, perhaps there is a bias / power supply problem, that may or may not be directly related to the ballast, IE, if main power was low or unstable, then vertical and horizontal sweep would be at odds with each other for consumption of what little stable power IS available, just a guess.

The schematic shows it should be 300 volts but there is around 280v seems it’s enough or the vertical depending on the problem I guess it could drag it down alittle bit.

Looking at Bobs schematic for the ballast and pictures of what I built I made a single change. The thermistor was installed between pin 5 (due to the pin switch for this chassis) and the intersection solder point at the top for the resistors. I did this because my chassis had the older version of the ballast installed originally and that made the pin setup different… a switch from pin 6 to pin 5 for one side of the AC line. Maybe I made a mistake somewhere? I don’t remember it getting to the realm of too hot to touch but I’ve made so many errors on this tv it’s hard to imagine what state of mind I was in when I did it!

Even after about 5-7 minutes checking voltages you cannot touch it it’s hot but I feel the voltages are in the right area. If a mistake was made on the ballast then there should be several discrepancies in the voltages. So if later on I find that there is infact a problem with the ballast I’ll just put one together with resistors.

That's what I have been trying to get at, from the info that Bob gave, it should NOT be getting that hot, if it is, that is a sign of a problem with the ballast itself or related to it, OR something loading way down to the point that there is dirty power from the voltage doubler.

what ever the problem is, you will have to be VERY meticulous and go over every part from the AC plug onward to find what is wrong.

This ts4h is full of surprises while the schematic shows 2 caps on a given tube pin the chassis actually only has 1 maybe this chassis was a production change because 2 other schematics 4d and 4j show the same as the 4h but this chassis is clearly different and these locations were factory never touched and including some capacitors have a different value.

We’ll…maybe I’m starting to feel not too bad about my failed efforts. Just want to publicly thank Tim for taking this on. He has been so generous with his skills and time. I know I have made numerous mistakes working on this piece but it appears it is a challenge and not the 1-2-3 get it going/works fine project. It’s in great hands and being worked on by someone who can actually check, test and problem solve in response to the expert suggestions given here. My most heartfelt thanks to Tim and everyone interested in this project’s success!

've restored a couple TS-4H and took a bunch of reference photos. Which tube and which pin are you referring to?