New caps, but still no power (Dell 3007wfp)

[ped90]

Hi all

I seem to have a bit of a stubborn monitor that doesn't want to fix. I'd love some help if anyone can provide it.

I'll start with the symptoms - plug in but no power LED or anything.
Opened up, caps looked fine but I thought I'd replace them anyway. I didn't bother with the big'un or the four little'uns near the centre of the power board (see video / should I have?)
Video:
http://1drv.ms/1MKb9Qu

Basically, after doing so, nothing has changed. I still get a noise when I plug the mains in (you can hear it in the video) and still no power LED or picture.

Can anyone advise on my next step? I'm no pro at all with this, so you may need to speak slowly
I've also 'checked' the fuse by just passing through it with a wire, but as there's that noise while the mains is plugged in, I guess the fuse is fine?

Thanks in advance!
Ped

[stj]

Re: New caps, but still no power (Dell 3007wfp)

small capacitors are the most important,
they start the supply and smooth the feedback to keep the output stable.

those are the first things i would have changed.

[ped90]

Re: New caps, but still no power (Dell 3007wfp)

small capacitors are the most important,
they start the supply and smooth the feedback to keep the output stable.

those are the first things i would have changed.

Ha, well there you go. Thanks, I'll do that when I get home from work and report back...

[budm]

Re: New caps, but still no power (Dell 3007wfp)

What DCV do you have on that big main filter cap (measure between the two legs of the cap)? >360VDC? The power supply board has PFC Voltage booster.
Also, is there something leaking from the legs of the main filter cap?

[ped90]

Re: New caps, but still no power (Dell 3007wfp)

What DCV do you have on that big main filter cap (measure between the two legs of the cap)? >360VDC? The power supply board has PFC Voltage booster.
Also, is there something leaking from the legs of the main filter cap?

I didn't ever see any leaks from anywhere on the board. Will have a double check there when I get back tonight though.
I currently don't have any measuring devices to check the main cap. I think it's time to invest! Can I get away with getting any old cheap meter or is there something specific I should look out for/get?

Cheers the for replies so far,
Ped

[ped90]

Re: New caps, but still no power (Dell 3007wfp)

Right, so I replaced the 4 small caps and now when I power on (not plugged into PC yet) the screen flashes red, blue, green, white... I think this is normal for when DVI isn't in. So I'm guessing that it's now fixed Thanks for the help, stj!

Budm, I checked the DCV on the filter cap. It fluctuated a little at the start of the reading, then levelled out at 374V. Is this ok?

[ped90]

Re: New caps, but still no power (Dell 3007wfp)

It works
Thanks for the help. Let's see how long it lasts :P