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.
: Forward and reverse bias depend on what type of ohmmeter are you using, here I'm using a Japan Standard
Using an ohmmeter
set it to X10
to see much easier the leak
from the diode in reverse 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.
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!
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