Main > Monitor/Video Forum
Zenith CRT TV - black horizontal bars
romshark:
I had gone with the LCR Research Pro1 unit. It got pretty good reviews, so hopefully it'll work for me, and it's in a neat "tweezers" form factor, and do more than just ESR measurement. It wasn't exactly cheap though, but it's already shipped.
I did try putting everything back together and testing it out, to see if there was a loose connector. Same exact problem with the picture. So I'll let it sit and discharge it next weekend, and go from there.
Zebidee:
That LCR Pro1 unit looks like a nice bit of kit with a lot of useful functions.
Remember to discharge capacitors before testing (put screwdriver/pliers across terminals), although this is really only an issue for the bigger caps and they usually discharge by themselves within a few hours. It is more of a danger to your equipment than to yourself, though some caps can give a nasty jolt. Essentially they are just like the CRT and can hold a charge for a while (another way to look at it is CRTs are basically big capacitors).
pbj:
Well, if you’re lucky Ken Layton will notice this thread.
Doesn’t look like a geometry issue to me, but I’ll defer to the expert.
Zeniths, at least in the USA, were not a particularly good brand of television when new.
Zebidee:
--- Quote from: pbj on July 12, 2020, 10:57:25 pm ---Well, if you’re lucky Ken Layton will notice this thread.
--- End quote ---
We're all lucky that Ken hangs out here and pokes his head in from time to time :cheers:
--- Quote ---Doesn’t look like a geometry issue to me, but I’ll defer to the expert.
--- End quote ---
Nobody here talking about geometry... :dunno
--- Quote ---Zeniths, at least in the USA, were not a particularly good brand of television when new.
--- End quote ---
That's because they're a US company (Illinois).
romshark:
I got my meter on Thursday, and played around with it after work that night (measuring components on other boards laying around, and on some loose capacitors and other components I had). Works nicely, as far as I can tell. This one directly shows the correct units on the display (looking at other meters, I think they give readings that have to be cross-referenced on a chart to get the correct number?)
Discharged the TV again this morning and pulled it all apart again. I checked some of the capacitors, but I'm not sure what I'm looking for. Am I looking for significantly lower values than what's marked on it? Significantly higher? Or maybe it's bad either way.
For example, one capacitor I tested on the TV PCB:
1000 uF Listed.
890 uF measured in circuit.
898 uF measured after desoldering and testing loose.
I'm also still getting used to interference from other components. Another capacitor:
2200 uF Listed.
3128 uF measured in circuit.
2111 uF measured after desoldering and testing loose.
What's the threshold for a "bad" capacitor? That first one is off by 10.2%, and the second by 4% (if I'm doing the math right). Or am I looking at this wrong?
Also, the empty spot where that second capacitor was reads 626 uH, so there's a choke or something in that circuit (I wish I had a schematic to find out.) The meter should automatically determine series or parallel circuits, but I may try manually selecting the circuit type and see if that helps.
Sorry for the probably rather basic questions, but I want to make sure I know what I'm doing with this ESR meter. Even if I end up just replacing all the caps on the TV, I should learn to use the ESR meter for other projects and repair jobs.