HP w2007 white screen problem

[pcjiet]

Re: HP w2007 white screen problem

I replaced those 3 caps, they are 100uF 16v each, but the multimeter read the same voltage 6.3 v. What could it be? or may be this is the correct voltage?

sorry, the caps are 1000uF 16v not 100uF

[momaka]

Re: HP w2007 white screen problem

If one of the caps is shorted, how did you determine the value for the replacement? Most of the SMD ceramic caps are unmarked. Did you just use the datasheet for the AAT1164C as a reference?

No, unfortunately, I wasn't able to determine the value of the shorted ceramic cap, so I just replaced it with one of the same dimensions that I cannibalized off of a dead video card. I know that's not exactly the best approach about fixing things, but I figured putting in any ceramic cap in there should be better than leaving the spot unpopulated. I did this with two monitors, one of which I've tested for a couple of days and it's been working fine.

My guess is that you can use the AAT1164C datasheet (if you understand it). There is a section on page 16 of the datasheet that talks about the output capacitor, but unfortunately I'm not that advanced in electronics to understand it. However, the datasheet does give a typical application circuit on page 14, which calls for a total output capacitance of 47uF (C3) when the main boosted output voltage (Vout1) is 13.3v @ 300mA, and the inductor is 6.8uH. I'll speculate that as long as you stay somewhat close to this capacitance, that circuit should work. Since there are 4 ceramic caps on the main boosted voltage rail of your monitor, that gives you about 13uF per cap more or less. So look for a10-15uF multi-layer ceramic cap with the same dimensions.

Of course don't change those ceramic caps unless you've found that one of them is shorted.

[jetadm123]

Re: HP w2007 white screen problem

No, unfortunately, I wasn't able to determine the value of the shorted ceramic cap, so I just replaced it with one of the same dimensions that I cannibalized off of a dead video card. I know that's not exactly the best approach about fixing things, but I figured putting in any ceramic cap in there should be better than leaving the spot unpopulated. I did this with two monitors, one of which I've tested for a couple of days and it's been working fine.

My guess is that you can use the AAT1164C datasheet (if you understand it). There is a section on page 16 of the datasheet that talks about the output capacitor, but unfortunately I'm not that advanced in electronics to understand it. However, the datasheet does give a typical application circuit on page 14, which calls for a total output capacitance of 47uF (C3) when the main boosted output voltage (Vout1) is 13.3v @ 300mA, and the inductor is 6.8uH. I'll speculate that as long as you stay somewhat close to this capacitance, that circuit should work. Since there are 4 ceramic caps on the main boosted voltage rail of your monitor, that gives you about 13uF per cap more or less. So look for a10-15uF multi-layer ceramic cap with the same dimensions.

Of course don't change those ceramic caps unless you've found that one of them is shorted.

Thanks for the explanation. It's about all you can do since there are no schematics and the components are either unmarked or have a factory code on them.