Another Dell with backlight/inverter probs

[bob12345]

Hi,

My other Dell monitor a 1704FPTt is also faulty, when I connect it to the mains and press the power on button, everything operates as normal - power light turns green, Dell logo appears, but the backlight will light up then go out after a second or two. The desktop/standard no signal image can be seen if I shine a light at the panel.

Tests so far:
Swapped the panel + ccfls with another but same occurs. Tried only connecting 1 ccfl plug (out of the 4) at a time, but neither has worked.

Replacements so far:
Suspected from reading on here that the 4 inverter transistors were dead or at least one was playing up so replaced all of them (AOU402) with new ones.
Tested again same problem occurs.

Replaced the inverter IC - OZ9930G on the track side of the power PCB with another new one. Still no luck

All capacitors look to be in fine condition with no leaks or bulges. Could this be a transformer problem - I hope not as that probably means a junked board!

Anyone got any ideas?

Thanks

[PlainBill]

Re: Another Dell with backlight/inverter probs

Hi,

My other Dell monitor a 1704FPTt is also faulty, when I connect it to the mains and press the power on button, everything operates as normal - power light turns green, Dell logo appears, but the backlight will light up then go out after a second or two. The desktop/standard no signal image can be seen if I shine a light at the panel.

Tests so far:
Swapped the panel + ccfls with another but same occurs. Tried only connecting 1 ccfl plug (out of the 4) at a time, but neither has worked.

Replacements so far:
Suspected from reading on here that the 4 inverter transistors were dead or at least one was playing up so replaced all of them (AOU402) with new ones.
Tested again same problem occurs.

Replaced the inverter IC - OZ9930G on the track side of the power PCB with another new one. Still no luck

All capacitors look to be in fine condition with no leaks or bulges. Could this be a transformer problem - I hope not as that probably means a junked board!

Anyone got any ideas?

Thanks

Classic 'two seconds to black' problem. It could be a transformer, or it could be something else. I'll gladly walk you through the troubleshooting steps, but would appreciate a better (larger) picture of the back side of the inverter.

PlainBill

[bob12345]

Re: Another Dell with backlight/inverter probs

Thanks Bill,

Attached is a better pic - let me know if its ok.

Note that at Q106 - the transistor at the top right of the cluster, the solder from its bottom leg got stuck to another square pad directly below it, but i figured the tracks were connected together anyways so no big deal... hopefully!