lg 50ps3000 no picture

[thuss]

Hi

My 50ps3000 has got no picture. the led flashes blue approximately 6 times then stays on for about 20 seconds and then turns to red again.

I have opened the back and checked the voltages (va vs)and there is seems to be no voltages going to the y sus and the z sus.

The voltages going to the av board from the power supply are not what they should be.

all the fuses seem fine and all the caps seem fine, The power supply part number is EAY60716801

One fuse near the large filter caps takes a while to beep but when I turn the range up on the multimeter I do get a reading I assume its due to the 450v filter capacitors next to it?

Any help would be appreciated- thanks

[tom66]

Re: lg 50ps3000 no picture

Pull Z-sustain power and see if you get a dim red picture.

[martino]

Re: lg 50ps3000 no picture

One fuse near main caps takes a while to beep on your meter? That doesn't sound right.
Can you recheck that fuse? Should read the same as if you hold probes from meter together on 200ohm scale. Like 0.2 or 0.3. If its reading some higher and slowly dropping, that means fuse is bad and all you are measuring is a cap in the circuit.
Unless its not a fuse your measuring?

Definitely follow Tom66 instructions,you got a skilled member on your side with him ,just thought the fuse reading was strange...

[thuss]

Re: lg 50ps3000 no picture

Unfortunately there was no difference when I disconnected one board at a time.

So I removed the fuse in question (f801) and you were right it was blown plus a couple of mosfets and diodes were also blown all the resistors seem fine.

So I looked on the internet for a repair kit which includes replacing a ic- do you think I would need to change the ic( I cant tell if its blown or not)?

Thanks for your help

[martino]

Re: lg 50ps3000 no picture

That ic is a driver for or of the mosfets. You probably will have to change that yes.
I wouldn't know how to test it, you can try and find the specs of that IC and measure from the ground pin to the drain and vcc to make sure.
Any numbers on that ic?

[thuss]

Re: lg 50ps3000 no picture

the ic has the following numbers on it l6599D, 900D925 I will have a look at the datasheet and see if I can measure from the ground pin to drain thanks

[thuss]

Re: lg 50ps3000 no picture

had a look at the datasheet would pin 9 the pfc+stop be the drain?

[martino]

Re: lg 50ps3000 no picture

Don't have the data sheet here,can you post it?

[thuss]

Re: lg 50ps3000 no picture

sorry about the late response -it was the ic so thanks for your help