There was a Monitor that came in with no display but with high voltage. The heater was only 2 volt, by right it should be 6.3 vdc. The filter cap checked to be okay with ESR meter and left only the output diode. The output diode was tested with analog meter with the X1 and X10 K ohm range and found it to be good. As usual, if could not find the bad component, the next step was to direct replace the component and retest to see if there is any component that breakdowb when under load. Guess what i found, the output diode broke down when under load.
So, i retest again with my analog meter (set to X1 Ohm) to see if there is any erratic movement in the pointer. At first glance, you thought the output diode was good, but when i applied a little bit pressure on the diode with the help of the probes while still testing the diode, i saw that the pointer have erratic movement. That was the cause of the problem! In future, if you would like to test any diode, i suggest that you apply a little bit of pressure from the test probes and slowly see the result. Don’t test it fast as you may miss a bad diode. Hope this helps!