Acer VN7-591G-70RT Display Flickering

[Jaysean]

Hello Badcaps coummunity hope you all are having a bless day,

Hope I didn't post it wrong kinda new at forum site rules and tradition

So I'm dealing with screen flickering problem on my laptop.

I'm not quite sure if it's the display cable or the screen itself that's causing the issue,

so I'm turning to you all wonderful expert on Badcaps for some guidance. Your help is much appreciated!

[Screen Flickering](https://i.imgur.com/xK9vHqc.mp4)
[HDMI port to external display seem to work be working](https://i.imgur.com/snSC24e.mp4)

Hardware Info

• Laptop: Acer Aspire VN7-591G
• Display: LG LP156WF6-SPB1
• OS: Windows 10 LTSC 2021
• CPU: Intel Core i7-4720HQ
• Chipset: Intel HM86 (Lynx Point)
• Integrated Graphics: Intel Haswell-MB GT2 (Intel HD Graphics 4600)
• Dedicated Graphics: NVIDIA GeForce GTX 960M
• Display Settings: Default at 60Hz, as per the model specs
• Mboard: Hades HBS 14206-1
• Display eDP cable: WISTRON Hades HBS EDP Cable 860 450.02W02.0001 (Not sure if this is correct I just wrote down what on the labels)

What I've gather so far

• External Display Works: I've tested with an external display connected via HDMI, and it works just fine. So, it seems like the laptop's GPU is in the clear.
  
• Cold Temperature made it worse:This screen flickering has been a problem for years now but it got worse recently.
  Usually when the room gets cold it will starts with a slow flicker then goes faster and can last for about 5 - 10 minutes.
  The workaround I found is to cranking up the screen brightness to the max and set the background pure white and clear
  or minimize any darker color icons/element helped reduce the flickering and stabilize the display after a minute or so.
  
• Battery dead: My laptop battery is toast it won't hold any charge so it always plugged in when used. That might be playing a part as well.
  
• Cable and Physical Condition: I opened up the case and checked the cable connecting the main board to the screen (Haven't try unplug and reconnect in yet);
  it seems secure on both ends but don't know how to test. No drops or spills near the laptop, so there's no physical damage or cracks from the outside.

Looking for more Information

I would like to ask where I can find compatible display panel datasheets for this laptop. I'd like to check out the prices for possible replacement in advance and see if there are cheaper or possible upgrade out there.

Any recommendations for forums or websites where I can ask these kind of questions would be super helpful. Thanks you all in advance~!

The only site I search so far is this one:
https://www.panelook.com/index.php [But I'm not sure how to check if possible upgrade is compatible or not the eDP (2 Lanes) , HBR1 (2.7G/lane) version confuse me]

[Jaysean]

Re: Acer VN7-591G-70RT Display Flickering

So I been reading and researching as complete beginner. but I'm currently stuck and would like to seeking further guidance.

I've measured the voltage on both ends of the eDP cable. The side connecting to the mainboard shows 19V on all four power pins, but on the other end, 1 of the 4 power pins doesn't seem to have 19V. Could this be indicative of a damaged cable and cause the flickering?, or should I explore other potential issues on the inverter board?

Additionally, I'm curious if it's possible to obtain the schematic for the LP156WF6-SPB1 Display LCD. I'm struggling to identify what is what and finding out the first un-power pin on inverter board lead to, and I'm wondering if taking a picture of the interface could assist in troubleshooting?

Schematic Acer Aspire VN7-591G_14206-1_boardview from https://www.badcaps.net/forum/showpo...80&postcount=2

[mcplslg123]

Re: Acer VN7-591G-70RT Display Flickering

Connect the edp cable on both sides.All power source removed.Put meter in diode mode.Now put one probe of multimeter on 19V pin of edp connector and check with each pin on screen connector. It should buzz on couple of pins.If it buzzes,then you may be having difficulty in locating the pins on screen side and 19V is indeed reaching the screen.

[Jaysean]

Re: Acer VN7-591G-70RT Display Flickering

Thank you very much Mcplslg123 for your suggestion. I followed your advice and disconnecting all power sources then measuring the pin in diode mode

It appears that I initially misunderstood the labeling of the eDP 30 pin and LVDS 34 pins and assume it laid out the same way. The 19V_DCBATOUT_LCD appears to be correctly linked to the backlight power, with all four pins (25-29), while the last pin seem to (30) not connect by default.

I'm not certain if this is due to a short circuit in the inverter, causing it to affect other pins or the damage cables.

However, there seems to be an issue with the 3D3V_LCDVDD_PWR pin and some other. That seem to buzz (shows voltage) on all the pins on the screen side. I'm uncertain if this is caused by a short circuit within the inverter, or due to damaged cables.

Here's a list of LVDS:Edp pins that I measured that seem to have issue: EDP_BLCTRL_CON, 3D3V_CAMERA_PWR, 3D3V_LCDVDD_PWR, and three of the EDP_AUX_CON pairs. It's possible that I may have missed some labels some, as my eyes started to become blurry after awhile.

Additionally, I've attached an Excel spreadsheet and images that highlight the pins with voltage issues and those that normal complete a circuit. I've also included pictures of the inverter board for reference. Apology for any blurry images

Could you please recommend the next course of action? Would it be possible to pull out the cable and check it without attach to anything just to be sure, or should I focus on the inverter board component next? Thanks you in advance and have a good day.

[mcplslg123]

Re: Acer VN7-591G-70RT Display Flickering

Its difficult to say anything going by the images. To me,mb seems ok-its either the edp cable or the screen itself. My bet is the screen is faulty. Try replacing that coil marked "100" on the screen with exact same markings. this works in some asus-not sure about Acer.

[reformatt]

Re: Acer VN7-591G-70RT Display Flickering

I'd say damaged LCD if it came across my bench.