Does this description make sense?
 

I'm writing a novel about a teevee repairman circa 1961. You guys have been so helpful so far and I've stored away info you've already given me. Anyway, I wanted to include a routine color teevee repair job and stole some stuff I found on the web and tried to match it with some stuff I found in the vintage teevee repair books I bought. Does the following sound realistic? My main character is repairing Mrs. Amato's teevee in his shop.
:scratch2:
The color set was a '58 RCA Anderson with a CTC-7C chassis, a heavy beast. It drew 380 watts of power and had over 22 kilovolts of zapping power. He had to be careful and couldn't tinker with it while Mrs. Amato tried to shove cookies and tea down his throat, so he brought it to the shop.

A few years earlier, she blew almost eight hundred bucks of her late husband's insurance on the new set and complained when all her shows weren't in color. He explained most shows weren't broadcast in color and she should save her money and return it for a nice black and white set. Nope. She wanted to be ready for the color revolution. She'd read in Life it was coming.

The problem was the image, though centered, was very small. As usual, he wore his sneakers and kept one hand in his pocket as he worked. He started by testing the tubes--twenty-eight of them!--and found a short in a filter capacitor. That blew one of the 5U4 rectifiers. After replacing the bad parts, the set worked good as new and he lived to talk about it.
:sigh:
Thanks for any advice.

He was looking for a power supply problem and tested the 5U4s last...?

This is why I depend on you guys. For a run of the mill issue with this set, what should the problem be and what should his testing order be? Thanks!!!

You could write that he was so annoyed by the owner or the children, that he elected to take it to the shop and do the repair there (for a higher fee), in spite of already knowing the simple fix needed for the set.

Mrs. Amato could also possibly degauss the picture tube with the vacuum cleaner running nearby, creating a swirling rainbow mess on the screen as she moved the sweeper back and forth.

Just a couple of ideas, hopefully helpful.

He tested all the tubes first, and found a shorted cap? I would not have spent time testing tubes that could not cause the problem. That would have been a waste of time as far as trouble shooting a power supply issue such as a small raster. He also would not have found a shorted cap by testing the tubes. The cap probably would not have been shorted, but leaky. This would load down the power supply and cause low B+ voltage. This would cause a small picture. A dead 5U4 would cause a dead set.

Thanks, but Mrs. Amato doesn't have children and I wanted it to be a real repair. I do like the swirling rainbow mess, but he would be able to see the interference on the spot if that were the case and he wouldn't bring the set in to the shop.

Damn, I wish I knew how to translate what you're telling me into prose.

So if Mrs. Amato had a dead set, does that mean the power wouldn't come on? Or does it mean it clicks on but there's a black screen?

If there was no power (or is it low power?), would he take it into the shop? If so, what would he test/look at first? The 5U4? Thanks.

When the picture is very small on the screen does that mean there's a power supply problem?

Actually, with the vacuum cleaner scenario, the picture could remain discolored after she ran the vacuum cleaner. I don't think the CTC-7 had a degausser circuit, so the image would be stained with poor purity until it was properly degaussed by a tv repairman.

A dead set would act the same as an unpluged set. A shrunken raster can be caused by a power supply issue, and in some sets by horizontal issues (the horizontal output in addition to horizontally sweeping the CRT it also generates the 20KV HV, and a boosted B+ supply that is often used for part of the supply of the vertical, and sometimes other circuits).
So partial failure of either could drop the raster size down to the point of being objectionable to the owner.

Once one knows what to look, listen and smell for one becomes able to isolate the problem to 1 to 6 tubes and the parts arround them (in most cases) without takeing the back off. From experience I can say that this skill is a double edged sword allowing me to find and fix fault fast (when I'm thinking clearly), but it also makes it hard to watch TV as I end up constantly scrutinizing the most piciune details of the image constantly gauging the preformance of the circuits (unless I'm super lost in a good program).

I wish I could hand you a scenario that would require benching a set, but I've never worked on other people's sets before so I don't have a good idea of what jobs could be done in home easily.

No way a Tech would test all the tubes first thing, he'd have a pretty good idea what section the problem was in and start there.
As David mentioned the 5U4's would be the first on the list to test in this case, also a shorted filter would most likely take out the Heater in a 5U4 making it very obvious at a glance that it was bad.

Ah, I see now. That's pretty cool. But he wouldn't bring it back to the shop, would he? Could he degauss it there? Of course, he might want to bring it back to the shop to see what's inside because he's not all that familiar with color sets. I've been flipping through my old teevee repair manuals and can't find this problem (or it's staring me in the face and I can't recognize it). How does he fix the poor purity problem? Thanks!

Unfortunately, I'm a moron when it comes to this and I need specifics for my character so that he'll sound like a repairman. (The story is from his POV.) Let's see if I understand what you're saying.

Problem: Tiny picture aka shrunken raster.
Cause 1: Power supply issue
or
Cause 2: Horizontal output "sweeps the CRT?" and generates the 20KV HV (high voltage?) and B+ supply used for vertical (and other circuits)
Task 1: Identify where the power problem is occurring.
or
Task 2: Identify the tube/s making the horizontal output sweep the CRT

I told you I was a moron at this. Thanks.

Thanks, Eric. Heater is a new term for me.

Actually, I found something on the web and took pieces from that.
http://www.vintagetvsets.com/ctc7.htm
It said:
My first attempts to check the chassis led to the destruction of one of the 5U4 rectifiers due to a short in one of the filter capacitiors, fortunately nothing else (like the power transformer) was damaged.

So in one of my repair books, it connected a too small picture with the 5U4. That's why I wrote the scenario as I did. But I'd already mentioned he'd brought the set to the shop, so I figured he'd need to test the tubes in the shop (you guys are always testing tubes and I thought that was the first step).

Sorry that this is such a foreign language to me. I appreciate your help.

:DTThat sounds like a few of the old biddies i ran into during my years as a road techie (as well as an in-shop techie).
Well, first off i never knew a road techie who 'wore sneakers' specifically for electrical safety or kept one hand in pocket while working on a set in-home. I never knew one to routinely carry a tube tester into the home either. The test for a given symptom is to substitute the suspected tube(s).
But to address your specific scenario of a shrunken raster on the CTC-7, the very first thing the techie would know to do is substitute the 5U4s. But since there's no improvement, this indicates the 5U4s are not the problem. However the shrunken raster exhibits a hum bar, that is, a dark band that slowly scrolls vertically through the picture, accompanied by an S-bend in the sides of the raster that scrolls with it. This is the classic symptom of the main filter capacitor gone bad. The set would have to be shopped for this repair.
But note that the raster could not be "very small" and still display a picture. It would be pulled in maybe an inch or two from the sides along with the telltale hum bar.