Just to give a background to the question:
A few days ago I got a nasty shock from a output of a 12V power supply adapter (SMPS) . when I checked resistance between a mains supply pin and output pin, the resistance read about... hmmm not sure the exact values, but it was in the kilo ohm range. So I opened up the unit and checked the isolation stage. The resistance between the capacitor connecting the primary and secondary stages (where the so called Y capacitor, blue color normally), read about 12 kohms.
The capacitor was removed and checked and it read 12 kOhms. So the problem was indeed the capacitor. Later I replaced it with a similar capacitor and now things are back to working condition with isolation from mains.
My question is, why did the manufacturer use a class Y capacitor for the isolation stage. Class Y capacitors conduct at failure, this is a safety issue. Dont you think a class X capacitor should have been used so that the user would be protected in case of a failure?
A few days ago I got a nasty shock from a output of a 12V power supply adapter (SMPS) . when I checked resistance between a mains supply pin and output pin, the resistance read about... hmmm not sure the exact values, but it was in the kilo ohm range. So I opened up the unit and checked the isolation stage. The resistance between the capacitor connecting the primary and secondary stages (where the so called Y capacitor, blue color normally), read about 12 kohms.
The capacitor was removed and checked and it read 12 kOhms. So the problem was indeed the capacitor. Later I replaced it with a similar capacitor and now things are back to working condition with isolation from mains.
My question is, why did the manufacturer use a class Y capacitor for the isolation stage. Class Y capacitors conduct at failure, this is a safety issue. Dont you think a class X capacitor should have been used so that the user would be protected in case of a failure?