Crt tv vertical bands when RGB enabled.

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Rade
Posts: 3
Joined: Fri Jul 10, 2020 11:10 am

Crt tv vertical bands when RGB enabled.

Post by Rade »

Hi! my samsung crt tv CR-21N112Z has vertical white bands more visible on one side of the screen.
This occurs only when RGB mode is activated, composite video and OSD menu are not affected.
There are 3 film caps on the rgb lines that i've disoldered and checked, they were all within excpected capacitance.
I also removed the 3 film caps on the rgb lines and connected directly the lines, result was no vertical bands but the colors where not right,
i managed to mess up my ic chip in the process and had it replaced by a new one but vertical lines are still there.
I've already recaped some of the bigger capacitors (11 capacitors) but with no effect.
Anyways since there is a problem only when using rgb input i don't think it comes from those caps.
Tried with different cables and machines, but the bands are still visible.

Here is what it looks like, brightness is set to max so you can see it better:

Image


https://postimg.cc/XGVLspVD


Can someone help me fix this problem ?
Thanks.
Taiyaki
Posts: 1052
Joined: Fri Apr 04, 2014 11:31 pm

Re: Crt tv vertical bands when RGB enabled.

Post by Taiyaki »

Is that picture taken with a very high level of picture aka brightness or luminosity?

It could be an anomaly of that model, the best way to find that out is to try on a second CR-21N112Z but I hope it's fixable cause that looks very distracting.
Rade
Posts: 3
Joined: Fri Jul 10, 2020 11:10 am

Re: Crt tv vertical bands when RGB enabled.

Post by Rade »

Taiyaki wrote:Is that picture taken with a very high level of picture aka brightness or luminosity?

It could be an anomaly of that model, the best way to find that out is to try on a second CR-21N112Z but I hope it's fixable cause that looks very distracting.

Yes brightness is set to maximum, if i lover it it's less distracting but still visible on some scenes/colors, especially when screen is scrolling.
It's impossible to find an another CR-21N112Z, so i cannot check if it's design flaw unfortunately.
kamiboy
Posts: 1982
Joined: Sat Sep 04, 2010 4:40 pm
Location: Denmark

Re: Crt tv vertical bands when RGB enabled.

Post by kamiboy »

This looks like interference in the source. Like badly shielded SCART cables. Does it do the same for all RGB sources? Try a different system to isolate the fault to either the source of destination.
Rade
Posts: 3
Joined: Fri Jul 10, 2020 11:10 am

Re: Crt tv vertical bands when RGB enabled.

Post by Rade »

kamiboy wrote:This looks like interference in the source. Like badly shielded SCART cables. Does it do the same for all RGB sources? Try a different system to isolate the fault to either the source of destination.
Yes i've tested with other cables and sources, it's something with the tv itself.
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