A friend gave me a defective KDS K717 monitor. It would "blip
out" after a while. Of course, the one year warranty had just
expired, and getting it repaired would cost about as much as buying a
new one. I tested the monitor, it worked fine for about an hour
and a half, then it did indeed turn itself off. I noticed that
like other LCD monitors it puts off quite a bit of heat, and it has a
convective cooling system--as the electronics heat up, the heated air
rises out the vent holes on top, and cool air comes in from the vent
holes on the bottom. Unfortunately this results in a rather high
operating temperature, and is probably why something in the circuitry
failed prematurely. could I get it to run at a lower temperature?
First I disassembled it, and discovered that the cover of the power
supply case could be left off. I reassembled the monitor without
the internal cover (which is used for electrical noise shielding), and
ran the monitor for a day....it worked fine, so I gave it to my son to
use. After a few weeks he said it started to turn itself off
again, so we had to do something more drastic. I had one of those
$2 80mm cooling fans leftover from the last parts order, so we decided
to install it on the monitor in hopes of making it last a bit
longer.
The first step was to take the monitor apart. There are four
screws on the bottom edge, I removed those and pushed the bezel towards
the top of the monitor a little bit, and then lifted the bezel
off. Next I removed the six screws along both sides of the
display panel, and lifted it partway off, so I could unplug the wire
bundle connector from the power supply case, then unplug the four
pink/white backlight cables from the psu. After removing the
screw and the pedestal from the hinge, I removed the screws around the
psu case, lifted off the cover, and then unplugged the control board
cable and the video input cable, and removed the psu from the monitor
housing.
There are cooling holes in the back of the psu case, which dictated the
location of the fan. I set the fan inside the plastic housing and
drilled thru the fan's mounting holes to make the holes in the housing,
then drilled them out 1/32" bigger to clear the fan mounting
screws.
A 3" hole saw makes quick work of the big round hole in the
center. I pulled the wires from their slot and ran them inside
the housing before screwing the fan on. The housing is curved, so
two of the screws can't be tightened all the way without distorting
things. Since the screws go into the plastic fan with a rather
tight fit, I doubt they'll loosen up, although I suppose I could have
put some glue on them to be sure.
This is what the business side of the psu board looks like. The
outputs are on the connector on the lower right corner, and are plainly
marked.
I found the 12v and ground connections.
After replacing the board and the psu into the monitor housing, I
soldered the fan power wires to the psu board. I also trimmed the
cover to clear the wires.
It almost looks like it was made that way....but not quite. I did
file the hole to remove any burrs, but it would be nice to have a
grommet of some sort.
We've run the monitor for several hours, and so far it works ok.
Cool air blows out the top and bottom, so the temerature
should stay much lower than it did with the original design.
update: the monitor has been running for about a month, with no problems...the cooling fan did the trick!
