Need help diagnose Acer LCD monitor

[mikey5791]

Hi,

Recently found from storage a 17" Acer LCD monitor which I remembered was kept as
spare. The model is AL1717 and I try to connect this monitor to a working CPU.
Upon switching the monitor power button, the monitor display yellow standby light. Then after switching on the CPU power, the monitor briefly display about 2 second of Asrock logo (this is the CPU motherboard I am using); after that the monitor just shows blank black screen. By tilting a bit of my view, I can manage to see some gray shadow of Windows 98 screen (the OS I am testing).

Later I shut off all the equipment and changed to another same model monitor which fully displayed Windows 98 screen properly. Any help to diagnose the earlier 17" Acer AL1717 blank monitor is appreciated. I have some experience doing some testing using digital multimeter and capacitor meter with basic soldering skill.

 

[(*steve*)]

The first thing I suspect will be failed capacitors in the power supply.

The first thing to do is open up the monitor. If this is like most, it is a case of undoing a stack of catches around the bezel. I do this by getting some plastic (I cut up a plastic milk bottle, soft drink bottle etc) and wedging them into the join between the two halves then sliding them along. The first one is always the hardest and I have used up to 6 pieces of plastic to stop the catches from doing themselves back up. Once you have a side and a corner done it gets pretty easy.

Then it's a case of removing a metal cover, detaching some connectors (sometimes before, sometimes after, and removing the power supply board. (Easily identified, it has the mains power connector on it).

You will be rewarded with a board that most likely has four or more swollen capacitors.

You need to get good quality low ESR replacement capacitors and once fitted your monitor should be as good as new.

 

[mikey5791]

Hi Steve,

Thanks for the prompt reply. I managed to find some free time on weekend to open up the Acer monitor by sliding a few plastic ruler on four sides after prying carefully with a thin screwdriver. This really tested my patience as I do not want to create any major markings.

Then, I removed a numbers of screws,unplug video cable from video board and also unplug 2 sets of inverter cable (I think). Finally the power board (image 0410) revealed but did not see any swollen (bulging) caps. Even though they are not swollen, I decided to desolder & remove all the big size caps (image 0427 marked red) at position C818 (470UF 35V),C813 (1000UF 25V, and the four 680UF 25V caps at C134,C135,C123 & C122. My attached image 0429 shows all the 6 removed caps, brand is Capxon. I have read that this brand is not quality caps, so I will replace with some new caps I bought earlier. Image 0422 shows on bottom row the 6 old caps while the new 5 caps on top row, short of 1 caps which I reused a piece of Capxon 680UF 25V. I tested all the 6 old caps with a capacitor meter and the reading is within 10% spec. Should I keep the old Capxon caps for spare ?

After I soldered all the new caps and checking no dry joints (image 0432), I put back all the cable and screws and connect the monitor to my CPU. Wow, my Windows screen appears (image 0433) , switch on for an hour and it is still working now ! It is indeed excited to successfully rescue an item and have a spare working monitor.

Thank you for the good advice and help.