Re: ASUS VH238T blank screen with backlight
EDIT: forget about this post. On closer look I could see it was because of the Microsoft windows wallpaper mosaic thing
It just now started showing a vertical line.
It worked fine for almost 2 days.
Is this likely a tcon issue? Or a panel issue?...
Spoonicks
Member
Last Activity: 07-08-2023, 07:50 PM
Joined: 06-30-2023
Location: Spain
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Last edited by Spoonicks; 07-06-2023, 08:50 AM. -
Re: ASUS VH238T blank screen with backlight
I will look into replacing the caps.
Now that I have the monitor apart, I didn't manage to have the issue come back. Before it would come back consistently, after being on for a while.
Now, it has been 24 hours, and no issues
The only difference with it being apart, aside from being some sort of bad connection that got fixed, is that the chassis ground is interrupted. Since I have the boards out of the metal casing, they are not grounded with that chassis. Don't know if this is important and would indicate...Leave a comment:
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Re: ASUS VH238T blank screen with backlight
The flex is well connected, I managed to remove it, and reconnect it.
Been testing the flex cable, ground pins are: 7, 14, 17, 24.
The ground pins are the same on both boards connect by the flex cable, so I don't see any obvious shorts to ground....Leave a comment:
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Re: ASUS VH238T blank screen with backlight
It's a picture "artifact"
In reality they look normal. Can't spot any bulged caps, or that look like they leaked or vented.
I noticed this flex cable, connects ot the display's PCB. I wanted to make sure it's all the way in, but I am having one of those newbie moments where I don't know how to remove it, and I am scared I will break it.
...Last edited by Spoonicks; 07-04-2023, 04:23 PM.Leave a comment:
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ASUS VH238T blank screen with backlight
Hello,
I am having a problem with a ASUS VH238T.
The monitor started by just going blank, but the integrated speakers, and the backlight worked. The OSD didn't pop up, neither did the messages of DVI No Signal, nor the Asus logo.
Turning off the monitor, and turning it back on made no difference. But leaving the monitor off for a few hours returned the monitor back to normal. The problem will eventually return after a couple of hours.
Today, it started exhibiting another symptom: the display started showing a white image, that didn't take the whole screen.... -
Re: Samsung 2233SN no CFL backlight
I tested the ccfls.
Connected one at a time, one of them didn't emit any sort of visible light, and the transformer made a high pitch noise.
My procedure was to connect one ccfl, power on the display, look for light, power off the display, repeat for all 4 lamps.
Assume CCFL is the problem, it didn't work on any of the connectors.
Probably not worth it to replace the CCFLs. It was fun to attempt to diagnose it though, not something I usually do.
Need to study more about this....Last edited by Spoonicks; 07-01-2023, 08:34 PM.Leave a comment:
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Re: Samsung 2233SN no CFL backlight
I thought it would be AC since there is no retification after the transformer.
Havent tested one lamp at a time yet.Leave a comment:
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Re: Samsung 2233SN no CFL backlight
Yes.
It actually stayed on for 71 seconds atvone time. I measure this:
R76 1.05 V
R78 2.8 V
R71 2.53
R73 1.5 V
I tried to go back and read the valies on R78 and R71, and they came down from the 2V range to 1V. The backlight then failed again. I am not sure what isbthe normal value I should get.
Looking at the schematic I think I measure wrong, I was using DC in my multimeter, and the current is AC.
I will try to repeat the readingsLeave a comment:
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Re: Samsung 2233SN no CFL backlight
Can I test this, even if the lamps don't light up?
EDIT:
Answering my own question, with the backlight failing to work, I got 0 Volts across those resistors....Last edited by Spoonicks; 07-01-2023, 12:57 PM.Leave a comment:
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Re: Samsung 2233SN no CFL backlight
Is there a way to test for that? if I don't have any spare lamps?
If one of the lamps fails, then both of them go out?
Can you help me understand what pins are for the primary winding? I thought it would basically be 2 separate transformers in a single package. So, 8 pins total.Leave a comment:
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Samsung 2233SN no CFL backlight
Hello,
Have a Samsung 2233SN with no CFL backlight. Testing with a flashlight, I can see the image is displayed, but the backlight fails after some seconds.
Sometimes, after being off for a while, the backlight will remain on for a couple minutes, but most of the times it fails immediately.
I tried to follow the guide present in this forum, but so far I haven't de-soldered any components. I need some advice on how to proceed to diagnose this display.
Following the guide I tested the following:
The transformer...Last edited by Spoonicks; 07-01-2023, 11:33 AM. -
Re: New Members - please post your introductions here
Hello all,
Much like everyone else here, I am too trying to get a monitor back to life. Suspecting bad caps. This forum seems has a lot of useful materials.Leave a comment:
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