Dell 2007FPb - No power at all

[slawson2000]

I have a Dell 2007FPb. Plugged in there is no power what so ever. It was working. Then it would turn on, then after 20 seconds it would shut off, then would try to come on. Now, nothing.

I pulled it apart. There is a fuse looking think behind the place where the power cord plugs in. It seems to be okay.

Looking at the power / inverter(?) board it appears everything looks oaky with the exception of the C605 capacitor (the big one - 450v 180uF). One wire coming out seems to be corroded at the base of the capacitor.

Could this be my problem? What else should I be looking for?

The pics are not mine, but my panels look the same.

Thanks in advance.

[Lumberjack777]

Re: Dell 2007FPb - No power at all

If the primary filter capacitor (the big one) has corrosion; that could definitely cause the problems you are experiencing.
You can test it with a DMM and it should show around 170v DC when plugged in. (always use caution on the primary side)
Or you can simply replace it because of the corroded lead. It'll need to be replaced anyways.

[slawson2000]

Re: Dell 2007FPb - No power at all

I will plan on replacing it (if I can find something similar), but would like to test it anyway. 170v That is between what? Both side the of the capacitor? The positive side to ground? I can test, just not sure where to stick the leads.

Also, how much of all these parts needs to be connected to test? Can I just check that board with nothing else attached to it?

Side note, if I get this this working again. Can I remove the 1.5" x 2" usb board on the back of the metal case and just leave it off? I do not know if it will effect the operation of the monitor at all.

[Lumberjack777]

Re: Dell 2007FPb - No power at all

You should be able to test the primary capacitor without anything else connected. Plug in to the power board and test the two leads coming from the capacitor. Either on top or bottom. By then the AC current will be rectified and it should show around 170v DC. I like to put by elbows on the bench to make sure I have steady hands when testing.

Regarding the usb board. I'm not sure. I suppose you could try it without the board and see if it works.

You might get lucky and this will just be a replacement of that big capacitor.

[slawson2000]

Re: Dell 2007FPb - No power at all

Measures up at 166V from the bottom, everything plugged in but the screen... What next?

[selldoor]

Re: Dell 2007FPb - No power at all

I think on this model you may need the usb connected at all times as the standby voltage is routed through it?
Test the voltages on the connector from the power supply to the main board.

Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed

https://www.badcaps.net/forum/attach...7&d=1280167246

https://www.badcaps.net/forum/attach...6&d=1280167246

https://www.badcaps.net/forum/attach...4&d=1280167246

[slawson2000]

Re: Dell 2007FPb - No power at all

I will have to work on pictures. I simply do not have the equipment to get good close up pics (yet).

To test the power to the main board. All I see is the multiwire connection. Which one(s) are power? What should it be reading?

[slawson2000]

Re: Dell 2007FPb - No power at all

Anyone? Where to check voltage into the main board?

[budm]

Re: Dell 2007FPb - No power at all

This may help:
https://www.badcaps.net/forum/showth...007#post335335

[slawson2000]

Re: Dell 2007FPb - No power at all

Thanks, I will get through this at some point. But I fear alot of it is over my head.

[slawson2000]

Re: Dell 2007FPb - No power at all

Okay, I am going to need some help here. I read through the links, and I understand a bit (at least the overall concept - not clue on the details), but I have no idea where/what to test on the board. I have it apart, I have a cheap multi-meter.

Is the 166v enough? The primary filter capacitor (the big one) is the one that looks questionable. Should I replace it first or keep testing?

Currently the monitor is totally dead.

[slawson2000]

Re: Dell 2007FPb - No power at all

I managed to borrow a camera. Attached are photos of front and back. The third is a picture of the only bad cap I can find. I have a replacement, but have not put it in yet. It looks like it is leaking, but still tests as 166v as above.

Does this help? What should be my next step? Right now it is totally dead.

Thanks.

[budm]

Re: Dell 2007FPb - No power at all

I would replace the bad cap first since we can see that it is leaking liquid, if you tug on that lead, it may just come right off.
There is 8-pin SMD SMPS IC for driving the Gate of the main MOSFET for the main power supply. Can you read the P/N on it?

[slawson2000]

Re: Dell 2007FPb - No power at all

Replaced the cap. No effect.
Be more than happy to supply numbers... If I knew what a "SMD SMPS IC for driving the Gate of the main MOSFET for the main power supply" was. I am good with the tools, but not so much with the lingo or acronyms. Can you maybe describe more what I am looking for?

[slawson2000]

Re: Dell 2007FPb - No power at all

Okay I am guessing, I may be way off. On the board that is shaped like an upside down L, there is one thing I can see that has eight pins located more or less near the center. It is at location JR6 and the number son top are 200A6 - PYHW.

I found a picture of something I think is close online an attached it below. About the only difference is the last four letters. Does this help? Is this it?

[budm]

Re: Dell 2007FPb - No power at all

OK, this is the spec sheet.
Check Source resistor R615 (looks like 0.18 Ohms) to make sure it is not open.
Try heating the start up caps C606, C611 to see if you will get an out put on the DC output connector. You can test this power supply board by itself without having ant thing else hooked up to it.

[slawson2000]

Re: Dell 2007FPb - No power at all

Tested R615. It read 1.3 to 1.4 Ohms. But the meter also reads 1.2 Ohms with the leads connected. So I think it is close (1.4-1.2=0.2). Best I can do - cheap meter.

As I mentioned above, not sure where to test the DC output connector. I see the wires (all 9). Which ones do I test?

While I am thinking about it, heat up the caps with what? Candle? I just do not know. How hot?

Also I see the spec sheet, just not sure what to do with it.

Your help is truly appreciated, however I fear my ignorance is hindering the process.

[budm]

Re: Dell 2007FPb - No power at all

There are 2 test points at the bottom side of the board, TP711 (+), and TP712 (-).
just put your DC meter probes on those two points. Just do not touch anything in the hot side of the board (heat sink, traces, etc.)

[slawson2000]

Re: Dell 2007FPb - No power at all

Looks like I am getting 19.0v across TP711 and TP712
Next step?

[budm]

Re: Dell 2007FPb - No power at all

Your power supply is OK.
I believe the problem in on the USB/power supply board.
If you look post 2 where I made the diagrams, check those Diode in my drawing.
https://www.badcaps.net/forum/showth...07fpb+teardown