CIBOX C1905 Mod.: LW1922C dead

[Chyenne]

Hi all, I got hold of a 2006 CIBOX C1905 Model LW1922C to play with. No reaction at all when turning on.
After opening it I found F801 blown. With my untrained eye I cannot find anything obviously bad except maybe the discoloration underneath T502.
Caps are from Su`scon and TEAPO and look fine top and bottom. C803 (above F801) is a TEAPO XG-HS.

There is another thread here that dealt with this model very shortly but unfortunately died.
https://www.badcaps.net/forum/showth...hlight=LW1922C

Please disregard the staining around F801.
It is the result of a little ... mishap, when I was trying something that involved a small smd fuse and a few beers.
It didn't work.

Since I only have a multimeter to test components and no idea of what the next step should be, I thought I would ask you wizards, who helped me revive a few LCDs already by just monitoring this board.

Thanks

[retiredcaps]

Re: CIBOX C1905 Mod.: LW1922C dead

Since I only have a multimeter to test components and no idea of what the next step should be, I thought I would ask you wizards, who helped me revive a few LCDs already by just monitoring this board.

Good clear focused pics. It helps a lot.

I would check the bridge rectifier just underneath the largest cap for shorts. You can test pins 1-2, 1-3, 1-4, 2-3, 2-4, 3-4 "in circuit". Any resistance reading under 30 ohms suggests a short and warrants removing the bridge rectifier to retest "out of circuit".

[Chyenne]

Re: CIBOX C1905 Mod.: LW1922C dead

OK, I removed the bridge rectifier and pins 3-4 (if counting from - to +) read 0.5 ohm.

Would replacing this and the fuse be the first things to do?
Is it more likely that the component failed by itself or that it was shorted by another faulty component?
Would you recommend replacing the caps anyway? (Since they are on your bad capacitor list.)

Thank you

[retiredcaps]

Re: CIBOX C1905 Mod.: LW1922C dead

OK, I removed the bridge rectifier and pins 3-4 (if counting from - to +) read 0.5 ohm.

That is shorted and will have to be replaced.

Would replacing this and the fuse be the first things to do?
Is it more likely that the component failed by itself or that it was shorted by another faulty component?

You can also check Q804 (the power mosfet?) for shorts. Test pin 1-2, 1-3, and 2-3 for resistance readings. Again anything under 30 ohms suggests it is shorted. You can test it "in circuit" first (without removing it). If you get a reading under 30 ohms, then remove it and retest.

Would you recommend replacing the caps anyway? (Since they are on your bad capacitor list.)

I would change the fuse and bridge rectifier first. If it works, then change the caps.

[Rtech]

Re: CIBOX C1905 Mod.: LW1922C dead

If the mosfet is blown, then I would also check all resistors and Diodes around the Mosfet and Transformer, as there is usually a low value resistor in the Mosfet circuitry,and if the Mosfet has gone short cct, then the chance are that resistor is also blown.

[Chyenne]

Re: CIBOX C1905 Mod.: LW1922C dead

Another one fixed.
The mosfet checked out fine. Replaced the bridge rectifier and fuse and it has been working for a few hours now. Will replace the caps when I'm bored.

Thank you two for the fast and clear advice. I love this board.