I’m dating myself:
I replaced the picture tube in a 21" B&W TV because it was dark and fuzzy; it had been “rejuvenated” (anyone out there remember that technology?) a couple of times in the past.
The customer complained she could see raster lines.
I explained that’s because the trace is now in focus. She wasn’t totally happy but accepted the repair.
IIRC it was a Zenith with the unique hand wired chassis, those things held up very well.
Yes @circuitsmith, I remember as a kid once in a while the tv would get blurry, my parents would make a phone call and a tv technician would drive to our house in his big white van with the words “TV REPAIR” written on the side, and come inside with his equipment in tow and rejuvenate our TV’s picture tube. It seemed liked it helped the picture, but only for a sort while.
Speaking of elderly electronics, I have one of those old bakelite AM radios from the 1930’s that I’m trying to get working again. I think all it needs is one of the tubes needs to be replaced. But I can’t find a tube tester machine. Back in the days when the tv repairman would come to your house, what the usual course of action was in our house when the tv broke, we being on the lower income side of things, my dad would remove all the tubes from the chassis, put them in a paper sack, and take them to Safeway, where he’d test them one by one on their in-store tube tester. One would always be bad, but good old Safeway, they had the replacement tubes there on the shelf by the tube tester too! Living here in silicon valley you’d think it would be easy to find a tube tester so I could fix my radio, but so far I’ve come up short. Someone told me to go to a place that sells electric guitars, they might have one since guitar player sometimes prefer tube amplifiers, sounds better for some reason on electric guitars.
I still have a tube tester, but I don’t know the way to San Jose.