This CRT tv is
dead set, no reaction when the power button is pressed(
no standby led light). I've open the back panel and check the faulty parts.
As you can see the
fuse was badly burnt-out indication of excessive current due to short circuit.
I've checked the parts feeding the
AC line to the power supply board (Power cord, VDR, Ceramic capacitor, Coil, Posistor, Degaussing coil) one by one and I've found out that
one of the four
rectifier diode has a
leak which caused the glass fuse burnt-out.
Here's how to test the rectifier diode.
Good Diode
Note : Forward and reverse bias depend on what type of ohmmeter are you using, here I'm using a
Japan Standard(Sanwa Brand).
Using an
ohmmeter set it to
X10 to see much
easier the leak from the diode in
reverse bias.
Forward Bias : test the diode by connecting the red test prod of the tester to anode and then the black test prod to cathode of diode. You will see the pointer will
reads a faily low resistance(above picture).
Reverse Bias : test the diode by connecting the red test prod of the tester to cathode and then the black test prod to anode of diode. You will see at the picture(above) that the pointer didn't react (
remains in infinity). This is a
good diode.
Bad(leaky) Diode
Forward Bias will reads fairly low resistance.
Reverse bias
unlike the good diode the pointer will
also reads a fairly low resistance.After confirming that the diode caused the fuse from blowing I've decided to replaced all four diodes since I have a lots in my stocks.
Remember that when you installing the new diode on the board, make sure that you will make it in the
right polarity.
This steps is also applicable in the DVD Player,Flat panel, Projection, LCD TV, you have to disregard only the posistor and degaussing coil.
Have a nice day!
Thanks for using
Fixya.Jdvillanueva
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