8 June 2015
Symptom
This old 17” monitor gave a blank white screen whenever it started. Switching the main button on and off repeatedly or pulling the plug may reset the monitor but it will go back to white screen on next restart.
What was wrong?
A polyester capacitor labelled as 0.47K275V-X2 (0.47 uf shown as 2101 & 2102 220nf 275V in schematic diagram) has gone bad with only 2nf reading when it was removed for measurement. Though not affecting the monitor screen greatly, it was found that the 82 uf 450V electrolyte capacitor (2016 as shown in schematic diagram) has also gone bad.
How to detect faulty capacitors?
Many capacitors have to be removed first from the circuit board and use a multi-meter such as the following to take a reading.
As this meter of mine has an upper range of 200uf, capacitors higher than 200uf could only be measured by charging/discharging method using ohm meter. A good capacitor will start with very low ohm and slowly increase to about 1000 ohms or thereabout.
Ensure that the capacitor is always discharged before taking any measurement as the multimeter can be damaged easily by any electricity discharge.
Schematic Diagram of Power Board
This schematic diagram can be downloaded from here.
Reference
