Dell 2007FPb - No power at all

[slawson2000]

Re: Dell 2007FPb - No power at all

Well, apparently I can. I thought it may have been a burn or something indicative of a bad board.

Anyone else have any ideas?

[budm]

Re: Dell 2007FPb - No power at all

That looks like stain, can you clean it off with alcohol?

[slawson2000]

Re: Dell 2007FPb - No power at all

Could this be it? See the brown area toward the top.

[budm]

Re: Dell 2007FPb - No power at all

I do not have any more idea, I cannot find the spare board.

[slawson2000]

Re: Dell 2007FPb - No power at all

Should I get a replacement board? Anything left to test?

[slawson2000]

Re: Dell 2007FPb - No power at all

Next step?

[slawson2000]

Re: Dell 2007FPb - No power at all

FD3 to FD8 all read around 90 Ohms with leads in one direction, open with the leads switched.

[budm]

Re: Dell 2007FPb - No power at all

You will test for short /or low Ohm resistance reading in both direction on its 2 legs which will indicate bad diode. you can set to 200 Ohm scale on the meter.
You can see what the diode looks like in the pictures of that link.

[slawson2000]

Re: Dell 2007FPb - No power at all

I have not, what exactly am I testing? I see the diagrams, but not sure what side or how to test.

[budm]

Re: Dell 2007FPb - No power at all

No luck finding the board at the recycle place, but did you check these diodes as shown in the diagram? FD3~FD8.
https://www.badcaps.net/forum/showth...highlight=2007

https://www.badcaps.net/forum/showth...highlight=2007

[slawson2000]

Re: Dell 2007FPb - No power at all

Thanks, post it up when you can...

[budm]

Re: Dell 2007FPb - No power at all

Sorry, I have been busy. I will see if I can find the the USB/sub-power supply board (I have the main power supply and the Inverter board) so I can give you the test points, most of the time the two diode that are connected in parallel failed.

[slawson2000]

Re: Dell 2007FPb - No power at all

Anyone? Is this a lost cause?

[slawson2000]

Re: Dell 2007FPb - No power at all

Next step?

[slawson2000]

Re: Dell 2007FPb - No power at all

Not sure if I did this right, but was checking voltage two ways, between the two leads of the capacitors and also by one lead of the capacitor to the ground.

C44 and C60 - no voltage.
Could not find a C58, but C50 - no voltage.
U2, U5, U13 - no voltage.
J4/J9 pin 8 had no voltage.

However, the 19v from power supply is making it across to the logic (?) board and then across pin 11/12 to the USB/power supply board and then across the 3A fuse.

[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

[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

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

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

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.