Fixing my 19" Samsung LCD monitor

Posted on 2012-11-30 09:57

Recently one of my monitors at work was refusing to go on in the morning. I've got two: a Samsung SyncMaster 940T and an HP L1950. Its sort of a wierd setup in that the (now quite old) PC I'm using came with a single VGA output, so I ended up buying an add-on DVI card, but I usually end up with whatever parts are left over after deploying stuff and I could only scam one DVI screen so I've got one VGA and one DVI screen hooked up. The problem was that every morning the screen was blank but the power light was blinking in a sort of double flash pattern. There was no message on screen for "No Signal", and I know now that the blue light means that I was getting signal, but the monitor couldn't display it.

I'm currently running Ubuntu 12.04, and of course I thought it was something wrong with my configuration or that a recent update had broken my video config and I spent undue time trying to correct it, failing, and eventually breaking my system. After fixing what I broke, yesterday morning when it happened again I started to realize it must be a hardware problem in the monitor. Once booted up, the machine acted like the monitor was working, the mouse would disappear as I moved the pointer to the other monitor, xrandr showed both monitors detected, the display settings looked fine. It seemed like either the LCD was dead (or the light behind it) or something driving the light was blown.

This page describes the possible repair. Getting online I found this seems to be a common issue in Samsungs: that the capacitors in the power supply blow out. Normally I would probably have given up at that point, but I still don't have a spare DVI monitor lying around and I couldn't bear the thought of going back to just one if only for as long as it would take for one to come in so I opened it up, removed the power supply and brought it over to a friend in electrical engineering who quickly identified two blown capacitors. We desoldered the bad ones, replaced them with two identical value caps (we had one of our assemblers do the soldering since I would probably be fumbling with it for a half hour and ruining the board while she had it done in under a minute). I reassembled and its been working fine since!

addendum: I just looked it up and we bought the Samsung on Sept 2, 2005 (for $319) so we've gotten a pretty good run out of it!

The real reason I like the Samsung.