Hi all,
A friend of mine came recently to ask for my help to check a HP2009f LCD monitor with no display which I said will try my best. First thing I do is to plug in the power cable and switch on, but no display, not even blue led light on the power switch. I shine a torch light at the screen but also no dim shadow at all.
The next day during my free time, I opened up the case and check for burn mark,any bulging caps on the power board or driver board or any bad solder joint but i was not able to see any burn mark,bulging caps or bad solder. I desoldered one cap at C864 which is a Suscon 560uf 35V electrolytic caps and it read 565 on a capacitor meter. So I just assume the other caps at C862, C40 & C48 which all looks ok should not be the problem here. I use my capacitor meter to check most of the caps and found all reading is within 10% range as printed on the caps.
After that I reflow new solder on cap C864, plug in a power cable and switch on mains, paying extra attention to check DC voltage on the biggest cap at C854 which is a 120uf 450V main cap. My digital multimeter on DC reads 325V which I think is normal. I also use an analog multimeter to check fuse at south of F850,which shows continuity. Is this meaning the power board has all the necessary voltage ?
Now I suspect the backlight lamp could be ruined, so I connect a 12V SLA battery to a CCFL tester (output 900V) and output to one of the lamp cable and found a dim light glowing on screen. The other three lamp cable also tested the same with dim glow. Is this meaning the back light is still good? So I am bit confused now as to where else should I do further testing to trace which part is the culprit. I am familiar with using a soldering iron and owned a digital multimeter and a digital capacitor meter. Any help and suggestions is very much appreciated. Thanking in advance for anyone kind enough to guide me step by step.
A friend of mine came recently to ask for my help to check a HP2009f LCD monitor with no display which I said will try my best. First thing I do is to plug in the power cable and switch on, but no display, not even blue led light on the power switch. I shine a torch light at the screen but also no dim shadow at all.
The next day during my free time, I opened up the case and check for burn mark,any bulging caps on the power board or driver board or any bad solder joint but i was not able to see any burn mark,bulging caps or bad solder. I desoldered one cap at C864 which is a Suscon 560uf 35V electrolytic caps and it read 565 on a capacitor meter. So I just assume the other caps at C862, C40 & C48 which all looks ok should not be the problem here. I use my capacitor meter to check most of the caps and found all reading is within 10% range as printed on the caps.
After that I reflow new solder on cap C864, plug in a power cable and switch on mains, paying extra attention to check DC voltage on the biggest cap at C854 which is a 120uf 450V main cap. My digital multimeter on DC reads 325V which I think is normal. I also use an analog multimeter to check fuse at south of F850,which shows continuity. Is this meaning the power board has all the necessary voltage ?
Now I suspect the backlight lamp could be ruined, so I connect a 12V SLA battery to a CCFL tester (output 900V) and output to one of the lamp cable and found a dim light glowing on screen. The other three lamp cable also tested the same with dim glow. Is this meaning the back light is still good? So I am bit confused now as to where else should I do further testing to trace which part is the culprit. I am familiar with using a soldering iron and owned a digital multimeter and a digital capacitor meter. Any help and suggestions is very much appreciated. Thanking in advance for anyone kind enough to guide me step by step.
