William’s Workbench

A tutorial from SparkFun.

http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=115

I received a Viewsonic VP140 LCD monitor for free, but it did not work. Pushing the power button resulted in nothing happening. About an hour of tinkering and tracing circuits led me to suspect two electrolytic capacitors on what I will call the switched 12V power circuit. There was a F7304 power mosfet IC that seemed to feed a 12V bus that powered the main part of the circuit. This IC was getting good power and seemed to want to turn on but there was only the briefest flicker of voltage turning on when pushing the power button. There are two caps on the downstream side of this IC, C24 and C110 (I think, need to take pictures for this posting). I unsoldered these two caps and was rewarded with a green power light when pushing the power button. I replaced the two caps, buttoned back up and now have a functioning LCD monitor.

For anyone with a similar monitor be aware that there are several different PCB styles for this monitor. Mine is the 300 series (need picture of PCB here).

Futurlec has some really cheap prices on PCB manufacturing. I might have to try them out for my next project.

Futurlec PCB Service

This guy built his own: http://klabs.org/history/build_agc/