Contrast Problem In CRT Monitor
If CRT Monitor have contrast problem, the thing you must do is to adjust from the menu or button. Check the heater voltage make sure it should have about 6.3 Volt dc. Trace also from the contrast pin of video pre-amplifier to the pin of flyback transformer. I encountered Monitors contrast problem was due to a shorted ceramic capacitor along the ABL (automatic blanking limiter) and a resistor truned into high ohm.
There was a common contrast problem in DELL 15″ CRT Monitor. Even though the menu contrast setting already tuned to maximum, the contrast was just not enough. You will be surprised that if i tell you it was the fault of a defective EEprom IC data. After reprogramming, it worked perfectly fine! A bad and old CRT tube may cause dim picture (less contrast) and if you have tested all of the CRT socket point voltages to be okay-suspect a bad or a weak tube. If you have a CRT rejuvenator or a restorer, testing a bad tube only take couples of minutes. Hope in the future any contrast problem you will know where to begin to check. Have a good day!