LG LCD monitor flickering fix

by Avi SchneorUpdated: Jun 12, 2023diy-miscellaneous6 comments

How did I fixed LG-1970HR/HQ LG-1770HR/HQ LG-L1780U/UN LCD flickering monitor?

DISCLAIMER – Important!

My LG-1970HR monitor started to flicker on a random basis.
Searching for a fix I have learned that this fault is well known and can be linked to any of the following:
1. Power supply/adapter
2. Inverter PCB
3. LCD lamp

This monitor power supply is an external component and it is the easiest one to start with. In this guide I’ll show you how to fix the power supply that is the common cause of the flickering fault.

This is the model of the power supply this fix is dealing with.
My LG-1970HR monitor and probably other models as well, uses 42W 12V 3.5A power adapter model DSA-0421S-12 which is an external unit.

In order to fix this power supply we need to open it, replace some components and do some soldering work.
First check that you have unplugged the power adapter from the mains and that you have removed the AC power cord from it.
Note: this unit has capacitors in it so be very careful not to touch it to avoid getting electric shock.

1. Take the 2 rubber feet off and unscrew the 2 screws found under the feet.

2. Open the power adapter case in a diagonal movement.
First lift the edge where the 2 screws were located and then with a help of screwdriver and some pressure
release the 2 snaps that hold the other side.

3. This is how the snap looks like

4. Remove the cover and observe the condition of the components, especially capacitors.
In my case it was obvious that 2 capacitors were bulged/blown, a residue transfer was also found on the top cover which helped confirming this diagnosis.
These capacitors are identical – 1000µF 16V.

5. In order to replace the capacitors take out (lift) the electronics block and turn it upside down.
Unsolder the shield PCB on one side to gain access to the capacitors soldering points.

6. Now you have access to the PCB print side. Remove some of the thermal glue that hides one of the capacitor legs.

Capacitors location on the PCB print side

7. Unsolder and remove the defective capacitors.
Replace the 2 capacitors with same type.
Pay attention to polarity! Capacitor has polarity and you should replace each one to same position on the PCB keeping same polarity. Both capacitors minus (-) pole are facing the inside of the PCB as seen on photo.

8. When done soldering the new capacitors, cut excess legs and start assemble the power supply.

Assembly – assemble all parts in reverse order to what is listed above.

A. Return the shield PCB and solder its wire.
B. Assemble the electronics block and close the case. Start with the side with the snaps.
C. Reconnect the power cable and connect the DC connector to the monitor

Voila – start using your monitor. You have fixed your monitor’s flickering fault.
Have fun and enjoy your LCD monitor, Avi

For more How-To guides by Avi, Visit the main DIY page

You might find there useful guides such as :

Fixing Grohe flush system
12V Burnt LED bulb fix
How to repair LG refrigerator water leakage?

and more…

Comments, remarks and updates are welcome.
Some will be published, with hidden sender's details.

SEND your comment

Did you find this article helpful?
Did it save you time and trouble?
If yes, please consider donating some $$$ to help me cover the hosting cost involved. Thanks

To make a donation, please click the following PayPal button:

6 Comments

Lukas on March 18, 2022 at 10:38

AWESOME! This post saved my monitor!

I was about to throw it away as I was suspecting the actual backlight to be broken and had no time to investigate, but after seeing the 2 caps blown up in the psu I was super happy to be able to fix it that easy

Thanks for spreading this!
Reply
- Avi Schneor on March 18, 2022 at 10:55
  
  Thank you Lukas
  I’m glad my post helped you fix your monitor
  have fun
  Reply
Martin on November 7, 2021 at 18:45

I have a flickering LG L1960TQ monitor that I was about to throw away. It uses the same power supply. I replaced the two capacitors according to your tutorial and the monitor is working again. Thank you! It feels great to fix things yourself!
Reply
- Avi Schneor on November 7, 2021 at 19:20
  
  Hello Martin
  This is great news and I’m glad you saved your monitor from going into the trash.
  Thank you for the input
  Reply
Michael on May 10, 2020 at 20:32

Hello Avi, great tutorial! I own the exact same power supply however i stumbled upon a different issue. One of the smd resistors burned, it’s marked as R7-1 and it’s located right under a metal heatsink with one screw. Are you able to help me find a suitable replacement? Also, can i use 1600uf instead of 1000uf?
Reply
- Avi Schneor on May 12, 2020 at 10:03
  
  Thanks Michael
  As for the resistor, I reviewed the original images of 6. and 7. in my post and R7-1 resistor is marked “100”. Search Google for “SMD resistor code” I believe you’ll find your answer there.
  As for the capacitors, I strongly suggest using the same value in order to keep its functionality.
  Goof luck
  Reply