1.8V Voltage Regulator IC Problem In LED Monitor
The complaint was no power. This LED Monitor uses an external power adapter and the output voltage was tested good (19 volt DC).
Since the power adapter was tested good, I had to open it up and check on the mainboard.
If you take a look at the photos below, this Monitor consisted only three circuit boards- the mainboard, LED backlight driver board and LED controller board.
Since this is a LED Monitor so you would not find an inverter board. Inverter board is for LCD Monitor.
Once the metal cover of the mainboard was removed the first thing I do was to check for the SMD voltage regulator ICs. I saw two ICs ie; 1117-3.3 (output 3.3 volt) and 1117-1.8 (output 1.8 volt).
I began to test on these two ICs and found the 1117-3.3 was good but 1117-1.8 IC does not produce any output voltage. It has 3 volt input but no output. Both ICs datasheet you can find it from the internet. This was a good sign because if there was no output from this IC means the MCU IC would not work. If the MCU IC doesn’t work means it will not generate any signal to the power LED light.
Before I replace the faulty 1117-1.8 IC I measured between the ground and the IC output (pin 2) with an Analogue meter set to x 1 Ohm. It gave a high and a low reading which was good. If I get two similar low Ohms reading this means there could be something shorted that had caused the 1117-1.8 IC to stop producing output voltage.
It was easy to replace this small SMD IC and after replacement was done and powered On, I could see the blue power LED light.
When I measured the voltage it showed 1.837.
If you want to become an expert in LCD/LED Monitor repair you can check out my ebooks below:
Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
P.S- If you enjoyed reading this, click here to subscribe to my blog (free subscription). That way, you’ll never miss a post. You can also forward this website link to your friends and colleagues-thanks!