Hi, My first post here, so hopefully i will get it at least sort of right!
I have had some experience in the past of repairing flat screen monitors, i have one of those ultra unreliable 19" Proview monitors, and in it's time i have changed it's lamps, replaced some bad cap's, and replaced the logic board when that gave up the ghost. So i am up for the challenge of fixing my current problem on the HP.
The monitor in question is a HP W2007v. The problem, like the thread title says, it's turning on, but the back lights go out after a couple of seconds. The picture is visable when viewed with a strong light and appears normal.
Looking at the inverter/power board, all looks ok, no obvious signs of overheating on the board, and no obviously bad caps. So my attention turned to the lamps. I do not have any spare ccfl's to hand that i could substitute in order to try and identify a dodgy lamp, neither do i have the correct value resistor, so i moved straight onto the panel dismantling stage.
Once the lamp assemblies were removed from the panel i inspected them visually for signs of trouble, bad connections, signs of burning or arching etc. All looked very good.
With the tubes still in their holders (two tubes in the top assembly, two in the bottom) i plugged them back into the inverter/power board. I then turned the unit back on (minus the lcd panel) to see if any tube was showing signs of problems within that 2 seconds.
Now we get to the interesting point. upon powering up, the bottom pair of ccfl's lit up instantly and evenly. The top pair however did not even manage to fully light up in the couple of seconds before the board shut off the power. Both tubes in that pair started to light from one end, flickered a bit with the light managing to reach about 3/4 of the way along both tubes before power was cut.
My first assumption was that both tubes in that pair were faulty, either that or that there was a short between the pair of them in the wiring. But, to double check i then swapped the lamp assemblies over - plugged the good bottom set into the top sets power source, and plugged the suspect top pair of lamps into the bottom power source. I then powered up. Now plugged into the other half of the inverter the suspect lamps performed perfectly, came straight on in an even manner. But on the other half of the inverter, the lamps that had been good before were now failing to fully light in the 2 seconds.
So i am guessing this narrows the problem down to just one half of the inverter/power board? If so, what are going to be the likely suspects? I have my trusty digital multimeter and soldering iron. But what do you guys think i should be checking first, any likely suspects you think i should look at in particular? I am ok with diode checks and resistance and voltage readings, but much above that i will need advice. Apologies for the long post, but i hope it gives the needed information.
This is the board in question, a 6832177300P02 PTB - 1773 The suspect side of the inverter is on the top right in the first picture, or bottom right in second picture.
I have had some experience in the past of repairing flat screen monitors, i have one of those ultra unreliable 19" Proview monitors, and in it's time i have changed it's lamps, replaced some bad cap's, and replaced the logic board when that gave up the ghost. So i am up for the challenge of fixing my current problem on the HP.
The monitor in question is a HP W2007v. The problem, like the thread title says, it's turning on, but the back lights go out after a couple of seconds. The picture is visable when viewed with a strong light and appears normal.
Looking at the inverter/power board, all looks ok, no obvious signs of overheating on the board, and no obviously bad caps. So my attention turned to the lamps. I do not have any spare ccfl's to hand that i could substitute in order to try and identify a dodgy lamp, neither do i have the correct value resistor, so i moved straight onto the panel dismantling stage.
Once the lamp assemblies were removed from the panel i inspected them visually for signs of trouble, bad connections, signs of burning or arching etc. All looked very good.
With the tubes still in their holders (two tubes in the top assembly, two in the bottom) i plugged them back into the inverter/power board. I then turned the unit back on (minus the lcd panel) to see if any tube was showing signs of problems within that 2 seconds.
Now we get to the interesting point. upon powering up, the bottom pair of ccfl's lit up instantly and evenly. The top pair however did not even manage to fully light up in the couple of seconds before the board shut off the power. Both tubes in that pair started to light from one end, flickered a bit with the light managing to reach about 3/4 of the way along both tubes before power was cut.
My first assumption was that both tubes in that pair were faulty, either that or that there was a short between the pair of them in the wiring. But, to double check i then swapped the lamp assemblies over - plugged the good bottom set into the top sets power source, and plugged the suspect top pair of lamps into the bottom power source. I then powered up. Now plugged into the other half of the inverter the suspect lamps performed perfectly, came straight on in an even manner. But on the other half of the inverter, the lamps that had been good before were now failing to fully light in the 2 seconds.
So i am guessing this narrows the problem down to just one half of the inverter/power board? If so, what are going to be the likely suspects? I have my trusty digital multimeter and soldering iron. But what do you guys think i should be checking first, any likely suspects you think i should look at in particular? I am ok with diode checks and resistance and voltage readings, but much above that i will need advice. Apologies for the long post, but i hope it gives the needed information.
This is the board in question, a 6832177300P02 PTB - 1773 The suspect side of the inverter is on the top right in the first picture, or bottom right in second picture.
Attached Files
Open circuit on the secondary of the suspect side of the transformer. I am guessing that where the lamps were trying to light it was because the transformer windings were arching.
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