Samsung LE32B530P7WXXU No Power

[Easky15]

Hi all, I have here a 32 inch samsung tv which is showing no red standby led when power cord is connected, I tested the connector which supplies power to the main board and getting no voltage on any pin, both fuses on power board tested ok, i am geting 233.2 ACV at the first fuse and 130 ACV at the second fuse, I have tested all mosfets and diodes using atlas dca55, all caps on cold side of the board are also good. Only problem i can see is a small crack on the power board near one of the transformers but it does not pass through any traces, Not sure what else to test now.... Any help would be great. Thanks in advance.

[Easky15]

Re: Samsung LE32B530P7WXXU No Power

Anyone know what might cause this?

[nomoresonys]

Re: Samsung LE32B530P7WXXU No Power

are all the voltages on power supply correct?, caution HIGH VOLTAGE.

[Easky15]

Re: Samsung LE32B530P7WXXU No Power

no voltages on DC side of power board, I am getting 240 and 130v on the AC side of the board at both fuses

[selldoor]

Re: Samsung LE32B530P7WXXU No Power

Do you get HIGH voltage DC on the BIG CAP and if not have you tested
the bridge rectifier

[freakaftr8]

Re: Samsung LE32B530P7WXXU No Power

Yes you could have a problem with the bridge rectifier you need to test at the main caps. if you have voltage is the main caps I would start checking the 5 volt standby supply rail

[Easky15]

Re: Samsung LE32B530P7WXXU No Power

yes i have 329VDC at the 450v main cap.... how do i test the bridge rectifier?

[selldoor]

Re: Samsung LE32B530P7WXXU No Power

how do i test the bridge rectifier?

You dont need to - voltage from the bridge goes straight to the BIG CAP so it must be ok.

[Easky15]

Re: Samsung LE32B530P7WXXU No Power

how do i test the 5v standby supply rail?

[CapLeaker]

Re: Samsung LE32B530P7WXXU No Power

Here is a schematic for that power supply!

[Easky15]

Re: Samsung LE32B530P7WXXU No Power

Here is a schematic for that power supply!

Thank you..

[Easky15]

Re: Samsung LE32B530P7WXXU No Power

What do i need to check next?? Sorry im no expert at this...

[nomoresonys]

Re: Samsung LE32B530P7WXXU No Power

is there voltages marked on power supply at the connectors?, which are the cables going out from the power supply.

[nomoresonys]

Re: Samsung LE32B530P7WXXU No Power

keep in mind only touch what your testing cuz of high voltage on primary side.

[CapLeaker]

Re: Samsung LE32B530P7WXXU No Power

test both fuses again with the TV unplugged, DMM in the ohm scale. I just find it kind of fishy having 130V on that other fuse that feeds the PFC, but that depends on where the ground lead was. Check diodes and fets for shorts with DMM in diode mode.

[budm]

Re: Samsung LE32B530P7WXXU No Power

Please provide good clear pictures of the whole bottom side of this power supply board.

[budm]

Re: Samsung LE32B530P7WXXU No Power

test both fuses again with the TV unplugged, DMM in the ohm scale. I just find it kind of fishy having 130V on that other fuse that feeds the PFC, but that depends on where the ground lead was. Check diodes and fets for shorts with DMM in diode mode.

That is because he is not using the correct GND point for measuring the Voltages on the primary side, that second fuse is for B+ feeding the main transformer.
There is label for the connector on the bottom left of the board where he should list the Voltage readings of each pins for us to know what he is getting, the SCH also shows the pinouts.

[Easky15]

Re: Samsung LE32B530P7WXXU No Power

Please provide good clear pictures of the whole bottom side of this power supply board.

Hope this helps,

[selldoor]

Re: Samsung LE32B530P7WXXU No Power

Its not really clear enough - can you retake it - get it near a window for more natural light
and no flash.(adjust the camera for low light?) If you cant do the full board better try for the top right across to where is says "COLD" that will give us the connector and the labelling.

[nomoresonys]

Re: Samsung LE32B530P7WXXU No Power

try unplugging the cable from the power supply to the main board, see if the backlights come on, not sure if you described weather they come on or not.