Dell 9020 MT power issues

Question

I have a 2015 9020 MT with power issues. Was using it a few days ago and all of a sudden it just unexpectedly went dark. Nothing special was happening at the time, just using, and not touching anything except the mouse and keyboard. I unplugged it left it for a few minutes, held the power button and then tried it again and the fans came on and cycled up and down in waves, lights flashing etc and then nothing. I opened the case found the button on the back of the PSU and pushed it, all the fans ramped up (CPU, Case and PSU), green light came on and I could smell that burnt electrical smell.

I actually have 3 of these, and so I swapped the PSU from one of the others that is working and no dice, put the PSU from the one that is broken into the one that was working and it works fine, so I know 100% it is not PSU at all.

I also unplugged all the peripherals (graphics card, DVD, wireless card) and nothing.(first thing I did actually)

I also replaced the coin battery and left it out for a few minutes when I did that.

It's dead, no lights on the power switch when I plug it in, so I can't diagnose with the different flashing lights, as there are none. When I do the PSU test with the button, all 3 fans ramp up to wide open and led is green, which according to the help files tells me the PSU and all the peripherals plugged into the board are fine. When I do that the CD/DVD drive led flashes green on the front of the drive 5 times, not sure if that is a code or not.

Does anyone have any idea what the problem is here. I'm thinking power switch maybe, or some type of self protecting mechanism that says something has failed and there is no way we will boot up now. The fact that I get no lights at all after the first time is baffling me. I wish I had known about the flashing lights on the power button right at the beginning as it would have probably told me what was going on, but now that is not an option obviously.

Appreciate any expertise anyone can recommend. Thanks

JOcean · Answer

Pull all the RAM and try to power up. You should get beeps or a diagnostic error code of lights. The power button would be suspect if you press it and get no power indication at all but the fact that you sense a burnt electrical odor starts to sound like a MB issue. If you are ambitious, pull the MB from another system you have and swap it to the problem system.

Dee Blaszman · Answer

Thanks for the suggestion. I forgot to mention in my original post that I did pull all the ram and swapped it with the ram in the system that is working, and again, no lights, no nothing.

I am using the other two systems, so I can not pull the MB from the others.

Was thinking of trying the power switch from one of the other systems so I took a photo of the powerswitch connector on the MB so I could try and figure out how to unplug it from the MB and when I was looking at the photo I saw beside the connector what looks like testing leads, as there are two solder dots inside a painted box and below the box it says 40 OHM +- 15% IMPEDANCE_5 L3-GND.

I assume if I put my ohm meter across those two test leads that might tell me if the switch is any good?

Nothing looks burnt on the MB that I can see, not at least something big enough to cause that burnt electrical smell.

bradthetechnut · Answer

I'm with @JOcean that it's likely an MB issue 9020 MB's are fairly cheap on eBay. As for ohm meter and power switch, I'll have to let someone else answer.

Even if you didn't see anything, burnt capacitor can give off burnt electrical smell. And it doesn't look like any wires or plugs shorted or got hot, right?

bradthetechnut · Answer

@Dee Blaszman - I almost forgot to mention, good troubleshooting by the way.

JOcean · Answer

That does not sound like a power switch test point. The power switch is a momentary switch. That is when you press it the reading across the switch leads should be a dead short (zero OHMs). And momentary because it is only a zero OHMs while pressing it and returns to Infinite OHMs (Open) when you release the switch. That test point sounds more like a PSU voltage test point to the MB.

Dee Blaszman · Answer

Thanks for all who chimed in here. I agree, it's likely a dead short in the MB. That will be the second one out of the three that I bought that has failed (last one presented differently).

My reason for trying so hard to recover it is the Adobe Acrobat XI Pro software that I bought with it will be linked to that service tag and I never captured the licence key for that computer. When you go in with Dell Digital Delivery it looks at the service tag and then tells you the licence key, so if I simply swap HDs I suspect it will give me the licence key for the incorrect one. Since I bought them back in 2015 it doesn't look like I can get them through Dells online portal.

I did a reboot of one of the working Optiplex and I see I can see in the BIOS under Maintenance the service tag, but I can't change it as it is greyed out. I see there is a service jumper on the MB, would I need to jump that before I can change the service tag, or do I need special software? Google didn't help me with that question.

Thanks for all your help!

Optiplex Desktops

Dell 9020 MT power issues

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