Mintek DVD Power Supply Problem

Before i encounter this problem i am a new learner in this field of repairing electronics. The problem is when you turn on or press the button switch of this dvd the LED(light emitting diode) will lit and in a few second the led turn off. So usually the technician would go to the power supply section. Most of power supply of dvd has another pcb(printed circuit board) it is excluded from the main pcb. If you follow the ac plug going into the dvd that's the power supply section.. So i test all the components in the power supply section and it's all okay. So i decided to change the ic(intergrated circuit) UC3842 and nothing happened. When i saw the site of jestine yong which is expert in electronics the electronicrepairguide.com. I ask him what could be the possible problem. He said that to lit the led the output of the switch mode power supply should right. He said i should test the voltage regulator which is  cw7812 (note: and not 7809 and 7805). So i test the output of regulator and the output  is not correct . I desoldered out the regulator and supply it with my power supply which has a setting of 3 volts and up. So i set the power supply to 14 volt the positive aligator put in the input of a regulator which is the first pin and negative to ground which is middle pin of regulator and the third pin is the output. Look always for the datasheet in the internet. When i measured the output it has a correct voltage which is 11.95 volts. The measure you will get depend on the accuracy of tester. So i ask jestine again. Look for the near component that goes in the pin of that regulator, and i saw a common diode 1n4007. I measured and it is ok.This is the only pin going thru the pin of regulator and a electrolytic capacitor. So he advised me to move a little each components if its body touch the other components and i did these suggestions. When it came to moving the body of the diode the led lit and in a few second it turn off again. I measured it again with my tester which in a diode range and it is okay.(Note: be sure the dvd is unplug in outlet before measuring the diode) So i decided to replaced the said diode  and the power comes back. A few days past i measured again that diode which i replaced and you know what, it is open.And the dvd now still working and i enjoyed every movie i play in that dvd.