LG Flatron LCD Monitor dead

[tech2014]

Hi folks. I have an LG monitor that is dead. I found 5 bulging caps on the board, so I replaced them. Still no power. I checked the fuse and it is blown. Would bad capacitors cause the fuse to blow or not. i can t find any shorts anywhere.

Also, to test the power supply, I am going to use a bulb. Its 72W. I took a pic of the setup because I want to make sure I am doing this right. I removed the fuse and put one wire of the bulb on one side, and the other wire on the other end(series). I then have the power cord plugged into the board and into the outlet.

See pic below

[dick_barton]

Re: LG Flatron LCD Monitor dead

If I remember correctly didn't ReeceyBurger123 have a similar problem on a power supply that turned out to be the 450V capacitor. I see they are Samxon which the forum always says. Replace them they are trouble.
I would check the capacitance and ESR of the large capacitors.

[tech2014]

Re: LG Flatron LCD Monitor dead

I checked the ESR and it was good on both.

[dick_barton]

Re: LG Flatron LCD Monitor dead

Then your ready to go. Good luck.

[tech2014]

Re: LG Flatron LCD Monitor dead

so in the picture, is the setup right for checking to see if there is still a short somewhere.

[dick_barton]

Re: LG Flatron LCD Monitor dead

I can't really tell. You say you have a lamp in place of the fuse. Well that should limit the maximum current from the mains and give you a visual on the current flowing.
I don't know if it also needs a small load on the DC supply. This used to be the case when checking PC power supplies. You needed a small (0.5Amp) load on the 5V supply to allow the supply to run up.

[tech2014]

Re: LG Flatron LCD Monitor dead

Thanks, I just wanted to use the bulb across the fuse to prevent blowing the fuse in case I missed something.

[dick_barton]

Re: LG Flatron LCD Monitor dead

What rating fuse was in circuit. Is that a traditional glass bulb or an electronic one? 72W @120V so 600mA current flow.

[tech2014]

Re: LG Flatron LCD Monitor dead

3.15A 250V fuse. I power up with fuse across and when I powered up, the bulb didnt come on at all. I did get my 165V across the filter cap, so I assume the board is good.

[budm]

Re: LG Flatron LCD Monitor dead

3.15A 250V fuse. I power up with fuse across and when I powered up, the bulb didnt come on at all. I did get my 165V across the filter cap, so I assume the board is good.

So you have a good fuse (or you mean fuse is removed) in place and then you also have the lamp connected in parallel with the good fuse in place?
Right now the inverter circuit is not activated yet, so you need to supply BL-ON signal to the board to see what you get, the inverter circuit is the one that uses lots of power.

[dick_barton]

Re: LG Flatron LCD Monitor dead

I hope he meant that the fuse was in series with the lamp.

[tech2014]

Re: LG Flatron LCD Monitor dead

oops I meant lamp across not fuse lol.

[dick_barton]

Re: LG Flatron LCD Monitor dead

So has the power supply burst back into life?

[tech2014]

Re: LG Flatron LCD Monitor dead

yes. I tested the voltages and they are there, albeit jumping around because not enough of a load.

[dick_barton]

Re: LG Flatron LCD Monitor dead

Good

[tech2014]

Re: LG Flatron LCD Monitor dead

Put the monitor back together and it works. Thanks for the input guys.

[budm]

Re: LG Flatron LCD Monitor dead

Good.