LG LCD power supply

[budm]

Re: LG LCD power supply

5V shorted to GND without any other boards connected to the power supply board? How low is the resistance?

[vinceroger69]

Re: LG LCD power supply

dead short budm like shorting leads together .000 no other boards are connected at all just power lead and you can hear a tick tick nosie

[vinceroger69]

Re: LG LCD power supply

just found d200 reads shorted in circuit across all three pins just removing to re check.

[vinceroger69]

Re: LG LCD power supply

edit the above tests ok out of circuit.

[budm]

Re: LG LCD power supply

OK, let me find good clear pictures of the top and bottom side of the board, I hop shojimmy will have them.

[budm]

Re: LG LCD power supply

Do you know which revision so the power supply 6709900016 is? Per SJ there are A~E.

[vinceroger69]

Re: LG LCD power supply

6709900016 B many thanks budm being in the uk cant use there site.

[budm]

Re: LG LCD power supply

OK, SJ only has the picture of the top side of the board, so you will have to take really good pictures of the bottom side of the board for us.
Picture provided by shopjimmy.
LG 6709900016B (6709D0006B, 6709C0006B) PS

[vinceroger69]

Re: LG LCD power supply

OK, SJ only has the picture of the top side of the board, so you will have to take really good pictures of the bottom side of the board for us.
Picture provided by shopjimmy.
LG 6709900016B (6709D0006B, 6709C0006B) PS

budm the light here isnt very good today ive took the best i can at the minute i hope these will help for now.

[budm]

Re: LG LCD power supply

So it is the ST5V pin that shows as shorts?

[vinceroger69]

Re: LG LCD power supply

budm just a update i have just found a parts board ive tested the 5vst too earth and it also reads .000 so maybe this isnt the fault causing the clicking relay.

[budm]

Re: LG LCD power supply

I would not expect the 5VST to show 0 Ohm like that.

[vinceroger69]

Re: LG LCD power supply

on one of the pictures ive uploaded on the edge of the board theres two small capacitors that go across the 5v st and gnd pins these do read short on both boards sixth picture.

[budm]

Re: LG LCD power supply

I see two filter MLC CAPS on the 5VST pins, they may be shorted out.

[vinceroger69]

Re: LG LCD power supply

on both boards they all read shorted seems odd?

[budm]

Re: LG LCD power supply

They are basically connected in parallel because they are connected to the 5VST pins. I would remove one at a time to see if the shorts will go away otherwise will have to trace that 5VST connections to see where else it goes to. These MLCC they tend to fail as shorts circuit.

[vinceroger69]

Re: LG LCD power supply

They are basically connected in parallel because they are connected to the 5VST pins. I would remove on at a time to see if the shorts will go away. These MLCC they tend to fail as shorts circuit.

ok will do give me a few minutes.

[vinceroger69]

Re: LG LCD power supply

removed both of both good and parts board sill reads the same 0.00

[vinceroger69]

Re: LG LCD power supply

could bad capacitors cause the clicking? i could remove all and test esr etc as soon as you plug it into the mains it starts clicking the relay if you then remove all leads and just have the power lead in you can hear the psu ticking so im sure its a psu fault.

[budm]

Re: LG LCD power supply

We need to find out first as to why you are getting such low resistance on that 5VSTY output, we will have to trace out and see if that 5VST also used to feed other circuit on the board.