Before this happened, the picture was slowly starting to shrink from the right.
There was slight foldover on the right edge, and a bright line would appear down the middle of the screen in bright scenes. I was not watching the TV when the circuit breaker tripped. There is now no raster.
Someone (not here) suggested I replace the horizontal output transistor QX202 (Zenith 121-831 or NTE 283) but *first* replace RX224 (1.5 ohms transformer to ground) and CX227 50mf (in parallel). I assume this is the banded carbon resistor that I can just barely see with the chassis tilted out.
Before I go ahead with this, I'd like to have a second opinion as to whether this is the most likely scenario or if there are other likelier ones.
I do have high voltage, BTW.
Can I perform any simple resistance tests (I can't run the set) to corroborate what I have been told?
I do have the Sams schematic.
Your help most appreciated!
Thank you.
Frank

there is a capacitor (oval shaped can) with two leads on it. clip the lead to your right and power up set. i had same problem with a set i picked up on craigslist. pulled in with some a bright line close to the middle. this can is oil filled-look for its shape to be distorted,bulged,dented,etc.clip lead and power up. breaker shouldn t trip and you will have picture,but it will be ow.very small and no color. i have also seen the wrong tripler installed and cause similiar symptoms. i have a complete set like that that i am keeping for parts. if you need anything,let me know.

There's a 1/2-watt resistor, and a small electrolytic (sorry, can't remember the value of either,) that are mounted on the reverse side of the flip-down chassis, on behind the horizontal oscillator (9-90) module, and below the tripler. I wish I could be more specific, but it's been years. That resistor will be burnt and probably will crack in half when you touch it. If that's the case, the small electrolytic right next to it is leaky and caused the resistor to overheat. That's a 98% good guess at your foldover/shrink problem, IF it was intermittent at first.

As far as no raster, but has HV, check your vertical output fuse and the 9-92 or 9-147 vertical module. The fuse, if the G chassis has it, will be right next to the module. There's a beam killer circuit that stops the raster on those sets if the vertical collapses.

Charles

I believe KX250Rider agrees with my other source and is correct. The resistor is a 1.5 ohm and the cap is 50 ohms. Thank you for this corroboration. The resistor did indeed fall apart when touched. The horizontal output transistor finally became shorted collector to base so no raster. I have parts coming and believe this will solve the problem. Will post results.
Thanks to both for your posts.
Frank

I had that happen once. The cap is a 50 uF and the resistor is a 1.5 ohm. The HOT is an NTE238. The Horizontal driver module was also bad in mine.

Also check the 10-ohm 10-watt wirewound ceramic resistor (rectangular white one) on the top of the BOTTOM PART of the chassis... It may be open if the HOT was shorted. Otherwise, the shorted HOT usually just pops the circuit breaker.

Charles

An update: The 50mf/1.5ohm/transistor combo stopped the circuit breaker from tripping but I still have no raster. I replaced the transistor (on advice of my other source) with a Zenith 921-500 (replaces 800-764, 121-1029-01, ECG 165,SK3115,GE-237). I looked at the 10 ohm, 10 watt. I checked end-to-end
with the set off, got about 5W. Each end to ground was about 135V so the 130V source is present. The 10 ohm showed no sign of damage at all- no discoloration.
Are there any "live" measurements I can try?
My sincere thanks for your help.
Frank

Correction: Got about 5 *ohms*

Neglected to mention: I don't seem to have high voltage now as I don't get the
characteristic "crackle" when the set is first turned on. Will check the fuse but it looks OK.

Still no HV could be caused by a bad 9-90 horizontal module, the small horizontal driver transformer, or the tripler. The horizontal driver transformer should read around 96 ohms between the blue and red wire and about .3 ohms between the yellow and black. There should also be around 79 volts DC on the red wire. If this voltage is absent, check RX222 (800 ohm, 10 watt resistor) for an open condition. There should be 21.8 VDC B+ at point U4 on the horizontal module. This can also be measured at R815 (620 ohm, 1 watt) located on the horiz. module. The best thing would be to find a good horiz. driver module and swap it. I don't currently have one; but, I'm sure someone on here does. Like I sais earlier, I remember changing the cap and resistor and also having to change the horiz. module to get HV back.

Usually, when the tripler fails, it either cracks open and burns or shorts and trips the circuit breaker. The best way to check it is to unsolder the black wire coming from the flyback to the tripler. You'll have to remove the RTV that covers the terminal first. With the wire unsoldered and moved out of the way of the chassis or any other parts, turn the set on and see if you can hear a slight sizzle, see a blue spark, or smell ozone. I have also taken a screwdriver and drew an arc from the lead to the screwdriver. If there is HV there, the tripler is bad. I have also seen the triplers short in these sets and take the flyback with it; but, that has always resulted in a tripping circuit breaker and the flyback getting warm, even with the tripler unsoldered.

I believe the blue and red wires define a single coil as do the yellow and black so I would expect the R to be 0 for each of these measurements, which it is. Please tell me what you had in mind here.
I get about 140 volts red wire to ground.
*FLASH* HV back, everything perfect! The Horizontal Board felt a little sloppy when I wiggled it. Got out a pin and bent in the spring tabs on each
board socket. Voila! So it turns out the whole problem was the 50MFD cap/1.5 OHM res problem which originally caused right-side foldover and finally popped the horiz output transistor.
I have used the pin fix method on these modules many times before. Most of the modules eventually got soldered, but in anticipation that the high voltage section would eventually need attention, I didn't do the horiz or vert output ones.
My sincere thanks to all who have helped here, especially KX250rider and radiotvnut.
Frank