Dell Optiplex 760, error code 3-4

[tmcw]

Have a Dell Optiplex 760 that is giving a 3-4 error code.

The manual for the 760 lists the error codes, but for the 3-4 error code, it would be accompanied by a steady green or steady amber power light. When 3-4 is flashing on mine, the power light is off.

Both 3-4 errors relate to the RAM modules, but I've tested mine (and others) and they're all ok, but the 760 still won't boot.

The PC did boot up yesterday morning, I had the OS (XP) and the acquisition software running (it's connected to a fermenter system), but when I came back to it to start the acquisition, the PC was off. I had a spare 760 that I was able to swap in to get me going, and since then have tried lots of things to get the faulty one going again, RAM modules, disconnecting drives/cards/peripherals, differnet power supply, but still get the 3-4 error.

Any ideas?

[SMDFlea]

Re: Dell Optiplex 760, error code 3-4

Is there any caps that look bulged or domed on top

.

[tmcw]

Re: Dell Optiplex 760, error code 3-4

No, they look ok. The majority are KZG, and a few polymers, but they all look ok, all over the board.

[tmcw]

Re: Dell Optiplex 760, error code 3-4

I finally got a chance to take the processor cooler off, and found a melted component under it. How can I find out the specs on it, and will it likely be the only component that failed, or did something else take it out?

There was some dust in that area too, wish I'd taken a snap before I blew it away, but it wasn't too dramatic. Could the dust have caused a short to blow the component?

[dicky96]

Re: Dell Optiplex 760, error code 3-4

That's a MLCC capacitor - remove it. Does it read short at the moment?

You may as well check the MOSFETs her as well

The looks like a VRM (one phase) if there are more phases the same you should be able to find the value of the capacitor by looking at another phase

[tmcw]

Re: Dell Optiplex 760, error code 3-4

Yes, it reads open. And there are similar phases in the area, so it should be easy enough to determine the value.

I'll take the board out of the box, clean it up, and see how it looks after that. Even though I have another backup 760 (in addition to the backup now in use), and since it looks like I can use other Dell boxes with the hard drive easily enough (tested a 620 and a 755 and with some relevant XP Dell drivers added), I'm not sure I'd trust the repaired 760 if I do manage it.