Hello Dear Reader
I'm currently working on this Switch Mode Power Supply that is used in a Satellite Receiver.
It was working fine till the day I decided to clean the dust around my TV set. In order to make life easier, I unplugged all the devices, including the receiver. After the cleaning was done, and hooked up the satellite receiver properly, the receiver never turned on again.
However I must admit I wasn't sure if the cable went into the socket all the way (in the back of the unit), so I unplugged it and plugged it back again, doing this couple of times. And I also think the cable was plugged into the 110V so it was live, I would assume this ON and OFF, ON and OFF is what caused the damage, since there is no separate switch on the back of the unit like more expensive ones would have.
Next step I took the metal cover off, looked inside. I can't see any fried components, nor any smell; However, I could hear a hardly audible clicking noise, not sure where it's coming from (maybe the transformer), that clicking sound would continue for couple of seconds even after I unplugged the unit from the 110V Ac. The sound was actually a little louder after unplugging the unit, like a spark plug noise on a lawnmower while testing.
I started with the diodes, some I had to remove from the circuits some were fine inside the circuit. Diodes are OK. I checked the resistors those are also good. I checked the capacitors especially the 64uF 400V giant CAP, that is good too.
Checked the continuity on the Coil and the Transformer (it has 4 legs on one side 5 on the other).
I even removed the power MOSFET (IRF830) from the heatsink. I tested that with a voltmeter. Put the black lead to Source, red lead to drain, it was OL. Left the black lead on source, touched the Gate with the red lead quickly, then went back to drain with red lead, I saw some numbers on the voltmeter like 1200, 1489, 1800, then OL. So it was weird, numbers going up instead of going down.
I reversed the leads, I put the red lead on the Source, black on the Drain, voltmeter read from 420 to 580, I would assume .420 and .580 Volt (this would be the voltage that makes the MOSFET work?).
I did not do any live testing with the power supply plugged in, because I would need some advise what is that I should do next.
NOTE: The bottom side of the circuit board is flipped over for easier component trace. Under the black box is a card reader for certain paid channels. (one diode was removed while the photo was taken)
If needed I can post more pictures.
Thank you for helping me out.
I'm currently working on this Switch Mode Power Supply that is used in a Satellite Receiver.
It was working fine till the day I decided to clean the dust around my TV set. In order to make life easier, I unplugged all the devices, including the receiver. After the cleaning was done, and hooked up the satellite receiver properly, the receiver never turned on again.
However I must admit I wasn't sure if the cable went into the socket all the way (in the back of the unit), so I unplugged it and plugged it back again, doing this couple of times. And I also think the cable was plugged into the 110V so it was live, I would assume this ON and OFF, ON and OFF is what caused the damage, since there is no separate switch on the back of the unit like more expensive ones would have.
Next step I took the metal cover off, looked inside. I can't see any fried components, nor any smell; However, I could hear a hardly audible clicking noise, not sure where it's coming from (maybe the transformer), that clicking sound would continue for couple of seconds even after I unplugged the unit from the 110V Ac. The sound was actually a little louder after unplugging the unit, like a spark plug noise on a lawnmower while testing.
I started with the diodes, some I had to remove from the circuits some were fine inside the circuit. Diodes are OK. I checked the resistors those are also good. I checked the capacitors especially the 64uF 400V giant CAP, that is good too.
Checked the continuity on the Coil and the Transformer (it has 4 legs on one side 5 on the other).
I even removed the power MOSFET (IRF830) from the heatsink. I tested that with a voltmeter. Put the black lead to Source, red lead to drain, it was OL. Left the black lead on source, touched the Gate with the red lead quickly, then went back to drain with red lead, I saw some numbers on the voltmeter like 1200, 1489, 1800, then OL. So it was weird, numbers going up instead of going down.
I reversed the leads, I put the red lead on the Source, black on the Drain, voltmeter read from 420 to 580, I would assume .420 and .580 Volt (this would be the voltage that makes the MOSFET work?).
I did not do any live testing with the power supply plugged in, because I would need some advise what is that I should do next.
NOTE: The bottom side of the circuit board is flipped over for easier component trace. Under the black box is a card reader for certain paid channels. (one diode was removed while the photo was taken)
If needed I can post more pictures.
Thank you for helping me out.
