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  #31  
Old 02-02-2018, 07:34 AM
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zeno zeno is offline
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Quote:
Originally Posted by jr_tech View Post
Perhaps try the set at a different location... perhaps the interference is local to your house or neighborhood.

jr
Ditto Exactly what I was just thinkin. In todays world almost anything
that plugs in or even on batteries can cause subtle problems like this.
Basically they are all little interference transmitters due to cheap design,
quality, & failures. It can get into the set via the line, antenna or directly
into the chassis. 3 case histories ...........

1) When I sent CW it would turn one of my Zeniths on & off.
A better ground for the transceiver fixed that.

2) Brand new Zenith had lines on all low channels not on old set.
(It actually did but wasnt sharp enuf to see them much) It was the
only set on ears. Cure was a calculator was upstairs recharging.

3) Just had a planned black out. What to do ? Listen to AM radio !
Almost every channel had a listenable signal as far as 300 miles
daytime. When the power came back it went back to just a few powerful
locals & lots of garbage.

enuf fer now
73 Zeno
LFOD !
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  #32  
Old 02-04-2018, 12:17 PM
Outland Outland is offline
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Out of genuine interest, I picked up another Trinitron (for free), a 1992 KV-20TS27.

It has exactly the same flickering issue! It must be something in the power, and the Tripp Lite isn’t catching it. Any suggestions for a better unit?

What’s also interesting is that the ‘92 Trinitron is much fuzzier, even the OSD. I wonder if the set was always like this or it’s age-related.
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  #33  
Old 02-04-2018, 07:00 PM
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zeno zeno is offline
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A cheap set may actually work better BUT I got a feelin you will see
it on anything since you know about it.
You could try tracking down the source. Turn off all house breakers
except the one the TV is on. If it goes away turn them on one at a
time til it comes back. Then you know the line & can unplug things.
If you cant get rid if it turn the breakers back off & walk around with
an AM radio listening for hot spots. Remember it can be something on batteries
causing it. OH watch for loose cables on other things in the house.

good luck Zeno
LFOD !
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  #34  
Old 02-04-2018, 11:03 PM
Outland Outland is offline
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Sounds good! Maybe I’ll try another power conditioner.

By the way, my ‘94 Panasonic (RF-only cheap set) is immune.
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  #35  
Old 02-05-2018, 10:16 AM
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I got it. Putting everything else on the Tripp Lite, and connecting the Trinitron directly to the wall removes the lines completely.

Too bad the second Trinitron's tube is completely worn out, it is nice.

The '89 KV-20TS20 Trinitron has an interesting picture. The white sections are very bright, even with picture low, and the picture is very sharp, but it seems like dark details (such as shadows) have very little detail, even with brightness calibrated. The problem is very similar to the one described here.

I don't know if it is simply the decoder or something with the tube or circuitry. It does make some scenes appear very dim.
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  #36  
Old 02-05-2018, 04:03 PM
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Screen shot time !
The whole screen from a DVD or VCR not a game or cartoon.
Sounds like a common problem, gotta see it 1st.


73 Zeno
LFOD !
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  #37  
Old 02-05-2018, 08:29 PM
Outland Outland is offline
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Here is a photo from the show Becker. The first is the Trinitron, and the other is a screenshot from the DVD. My '94 RF-only Panasonic displays something far closer to the screenshot.





Look at his tie, her hair, and the sign in the background. Picture is at 25%. If the brightness is turned up further, the blacks become gray.
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  #38  
Old 02-05-2018, 09:03 PM
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Is the Sony being fed the same RF signal as the Panasonic that doesn't have the problem, or are you using a composite input on the Sony? Whatever is the cause, blacks are being clipped before the signal gets to the brightness control, if turning up the brightness just makes them gray.
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  #39  
Old 02-05-2018, 09:07 PM
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Quote:
Originally Posted by Outland View Post
I got it. Putting everything else on the Tripp Lite, and connecting the Trinitron directly to the wall removes the lines completely.
Well, now you could find out what's causing it by unplugging one thing at a time from the Tripp Lite and plugging it directly onto the line with the TV.
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  #40  
Old 02-05-2018, 09:26 PM
Outland Outland is offline
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Quote:
Originally Posted by old_tv_nut View Post
Is the Sony being fed the same RF signal as the Panasonic that doesn't have the problem, or are you using a composite input on the Sony? Whatever is the cause, blacks are being clipped before the signal gets to the brightness control, if turning up the brightness just makes them gray.
The photo is of composite, but I tried RF and it looks the same.

Here is a photo of the Panasonic showing the same scene.



There's a book in my university library covering CRT repair from 1989, it might be a useful resource for me.
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  #41  
Old 02-05-2018, 11:51 PM
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It looks like a bias problem, either in the CRT setup or the video circuits.
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