Dead Dell All-In-One PS

[GoneGault]

I have a Dell All-In-One with no signs of life. I have 120ac coming into the power supply, with no dc volts coming out. It has a proprietary 18pin atx connection, and a replacement ps costs more than the computer is worth. I see no obvious bloated caps or burn spots on the power supply board. Space is tight and power supply appears to be harder than average to work on. Output voltages are marked on the power supply board.
Question: as long as I match up the voltages and jerry-rig a connector, can I use a regular atx power supply to test the computer?
2nd Question: I have repaired a decent number of power supplies, lcd tv's and monitors. Should I attempt to repair the power supply?

[budm]

Re: Dead Dell All-In-One PS

Are you getting 120VAC on the two inner pins of the bridge rectifier?

[stj]

Re: Dead Dell All-In-One PS

under the chip in the upper left corner, someone has made a mess of the soldering.

an atx supply should be o.k. - compare the pinout - you may be able to just plug it in with the side of the connector overhanging.
check the pinout first though.

other than that, get datasheets for the chips - look for startup capacitors and change them.
and see what's hiding under the heatsink.

[GoneGault]

Re: Dead Dell All-In-One PS

Budm, if the bridge rectifier is in red in this picture, the two inside pins have 0 voltage.

[budm]

Re: Dead Dell All-In-One PS

Sounds like you have blown main fuse.
At the AC inlet, the center pin is Ground, the other 2 pins when you use Ohm meter between one of the inner pins of the bridge and one of the pin of the AC inlet, it should show <1 Ohm, do the same test on the other pin of the inlet, it should also show <1 Ohm. Basically each of the AC inlet pins (Hot and Neutral) should have continuity to the two inner pins (AC1, AC2) of the bridge.
The fuse may be cover with black shrink tubing.

[GoneGault]

Re: Dead Dell All-In-One PS

Budm, you are right...the main fuse is blown. I have order replacements and will report results when they arrive.

[GoneGault]

Re: Dead Dell All-In-One PS

I replaced the main fuse; it immediately blew again. I then used a fuse with a higher amperage and it also blew.

[c_hegge]

Re: Dead Dell All-In-One PS

^
That always happens. Fuses never blow without something else causing it to blow. Sounds like you might have a shorted PFC transistor and/or coil.