Repairing Computer Monitors That Won’t Turn On

Ever had a computer monitor that worked one day on not the next?  At my old IT job in College I replaced at least a monitor every week that had this issue.  Either the green light would come on and go away, flash, even sometimes make a buzzing noise. We just surplussed the broken monitors and put new ones in.  At my the job I have been at now for the past 3 years we were doing the same.  The issue was just as common here.  I now work at a manufacturing plant, it gets hot and there isn’t AC out there.  Monitors fail after a little while.

I finally popped one open and this is what I found.  I actually repaired the Dell monitors before taking pictures.  These pictures are of a HannsG Monitor that went bad.

Board XAD819AR EA02819X

Opening up any monitor seems to be the same process although just a bit different for each model and takes about 5 minutes.

  • Remove screws from back of monitor
  • Pry of screen bezel using a flathead screwdriver (Do the button area last)
  • Place back of screen aside
  • Remove cable that runs to the buttons on the front screen bezel
  • Place Bevel off to side
  • Remove 4 screws from metal shroud
  • Undo ribbon cable to monitor from the circuit board to back of LCD
  • Remove Power cables for what I am guessing are the backlights (Take a picture they need to go back exactly the same)
  • Remove LCD, set aside
  • Remove screws for circuit boards and pull the board(s) out, May have to remove screws from connectors on outside too.

At this point I look for bad capacitors.  So far this has always been the issue on the 10+ monitors and after replacement has fixed the problem 100% of the time.  To tell just by sight if a capacitor is good or bad is easy, this is not 100% accurate but has worked for me without fail so far.  If the capacitor is bulged on top at all, meaning not perfectly flat or concave, replace it.  Also if you see black rubber type stuff exploding out of the bottom, replace it.  Here are some examples of popped capacitors in the monitor I was fixing.

Leaky Capacitors Leaky Capacitors

Leaky CapacitorsOn this particular picture the two large green ones are definitely bulging, the single green on the right was questionable.  I did it anyway, by not replacing a capacitor that may be bad it could put undue stress on the others causing them to fail as well.  So if it is questionable just replace it!  Looking at this board it is unlikely 7 capacitors failed at a single time, it was most likely a chain reaction after one failed.  The two on the left (green arrows) looked completely fine, so I left them.  If you are worried just replace them all, it is your choice.

Now the replacement.  You will need a soldering iron and solder.  You will also need the replacement capacitors.  You can sometime find display specific kits.  I bought a generic pack of capacitors from amazon that covered about 10 monitors. The kit would cover more replacements, but some types were too commonly used.  Some of the capacitors I will have to special order the capacitors.  The place for those is digikey.com.

Watch this video to learn a little about capacitors and the dangers of doing this incorrectly.

Important Takeaways:

  • Take note of the capacitor orientation when replacing
  • Make sure the capacitance number matches exactly(uF)
  • Voltage needs to be the same or higher than the capacitor you are replacing.

This is another video I found walking you through the replacement of the capacitors on a dell 1905fpv.

So at this point you basically take your soldering iron and heat the backside of a capacitor lead and rock it back and forth as you heat the solder in the two pins.  Do take note of which side of the capacitor has the white lead, if you put it on backwards it will explode like seen in the first video.  Now you just put the replacement capacitor in and solder the capacitor on.  At this point, it is time to reassemble and test.

Capacitors Replaced

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