Hello community. I've got an ASUS VA27EHE with a Panda LC270lf1l01 panel that started to behave strangely. A bit of intro:
If you power on the monitor without any inputs it turns on, displays the ASUS logo, shows no signal and goes into standby normally. When you plug it via HDMI sometimes and more recently, most of the times, it distorts the bios logo with horizontal lines, then when loading into windows 50-50 the windows emblem also is in horizontal lines. And after the system loads it almost always works properly, lol. On some rare occasions a part in the top of the monitor is being distorted (if we divide in 5 parts, it'd be the 2nd part from the top, not the topmost). Most notably though, if I switch refresh rate to 75hz the monitor goes bananas and three fifths turn off while the topmost part is displayed properly and the one below is horizontal lined.
So I disassembled the thing thinking it's most probably a short on the CKV or something, but no. Checked the voltages on power board and panel board. On power board's high voltage cap the voltage seems a bit low (68u450v) at only 283v instead of like 300-320. Outputs are 17v to main board and 53v for backlight, caps on outputs were desoldered and tested, ESR and capacity were okay.
The panel board though, you can forget about getting a schematic for these Pandas since I saw 3 of those and funnily they all use same chips on different msi/asus/philips 24-27", but anyway, all the voltages besides Avdd seemed okay with Avdd being 10v (in all other boards with same dc-dc chip it was 13.5v).
VGH 23.3v
Avdd 10v
VGL -7.5v
Vcc 4.7v
Vic 3.1v
The CKV lines that are mostly causing the horizontal lines issues by being shorted aren't (at least in this case), between the lines there's a resistance in the megaohms.
The chip responsible for data between tcon and panel is a Novatek nt71263fg-720, it seems okay too, the outputs aren't shorted.
Did perhaps anyone have something similar in behaviour? I still didn't check the voltages on the main PCB, so I'll probably do that later. It bugs me that it's not a permanent issue, meaning it could potentially still be solved, unlike when the CKV is already shorted and burned inside the panel itself.
If you power on the monitor without any inputs it turns on, displays the ASUS logo, shows no signal and goes into standby normally. When you plug it via HDMI sometimes and more recently, most of the times, it distorts the bios logo with horizontal lines, then when loading into windows 50-50 the windows emblem also is in horizontal lines. And after the system loads it almost always works properly, lol. On some rare occasions a part in the top of the monitor is being distorted (if we divide in 5 parts, it'd be the 2nd part from the top, not the topmost). Most notably though, if I switch refresh rate to 75hz the monitor goes bananas and three fifths turn off while the topmost part is displayed properly and the one below is horizontal lined.
So I disassembled the thing thinking it's most probably a short on the CKV or something, but no. Checked the voltages on power board and panel board. On power board's high voltage cap the voltage seems a bit low (68u450v) at only 283v instead of like 300-320. Outputs are 17v to main board and 53v for backlight, caps on outputs were desoldered and tested, ESR and capacity were okay.
The panel board though, you can forget about getting a schematic for these Pandas since I saw 3 of those and funnily they all use same chips on different msi/asus/philips 24-27", but anyway, all the voltages besides Avdd seemed okay with Avdd being 10v (in all other boards with same dc-dc chip it was 13.5v).
VGH 23.3v
Avdd 10v
VGL -7.5v
Vcc 4.7v
Vic 3.1v
The CKV lines that are mostly causing the horizontal lines issues by being shorted aren't (at least in this case), between the lines there's a resistance in the megaohms.
The chip responsible for data between tcon and panel is a Novatek nt71263fg-720, it seems okay too, the outputs aren't shorted.
Did perhaps anyone have something similar in behaviour? I still didn't check the voltages on the main PCB, so I'll probably do that later. It bugs me that it's not a permanent issue, meaning it could potentially still be solved, unlike when the CKV is already shorted and burned inside the panel itself.