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  1. #1
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    Dell Optiplex GX620 ultra-small form factor does nothing

    Is someone a bit familiar with the Dell optiplex GX620 ultra small form factor PC?
    When I push the power button it does nothing: no LEDs, no fans, just total silence.
    The external power supply (brick) looks OK; the green light is on and it works with another Dell.
    Is there anything in the internal power circuit that can stop everything like a thermal break, fuse or something silly like the micro-switch behind the power button gone bad?
    How does that micro switch kick everything on? Is there a relay or some solid-state switch?
    Thanks for any good ideas.

  2. #2
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    ATX motherboards have the power supply connected to them and the On|Off switch, when pressed, tells the motherboard to get things started. The motherboard has power on continuously even when off which is shown by the small LED on the motherboard when viewing with the side of the case off. Most OTC/Over The Counter or aftermarket replacement power supplies I've worked with had an On|Off switch on them near the cord socket and fan, OEM computers usually don't have that. I've had some success with older computers in unplugging the 20/24 pin power cord from the motherboard [with the AC power disconnected of course] then putting it back, sometimes the problem never comes back.

  3. #3
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    Hi Berton, In the Dell case, the brick has 8 pins that mate to the connecter in the back of the case. That connector has its back pins soldered to the motherboard. The only connectors on the motherboard are 2 that feed 4 wires to each of the 2 fans and the SATA connections. Any thoughts on the possibility of a bad on/off switch? It looks like it's a pain to get behind it and jump his pins manually. It would be nice if these pins appear somewhere on top of the motherboard.

  4. #4
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    It could be a bad switch and sounds like it may have all the wires for the front of the case going to a single connector. That Optiplex sounds like a hermaphrodite, a mix of technologies between an SFF like the Inspiron 530S & 531S I have and a Notebook. My 530S and 531S use a standard power cord.

    Inspiron 530S
    Inspiron530S.png
    Optiplex GX620 - is that what you are working with, on the right?
    OptiplexGX620.jpg
    These images are from the Dell support site.

  5. #5
    Super Moderator BATcher's Avatar
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    It's probably no comfort but I was warned off the Dell USFF format because our technical support firm said at the time that their experience was that USFF system units were prone to power-supply problems. So we bought SFFs!
    BATcher

    Time prevents everything happening all at once...

  6. #6
    Super Moderator jwitalka's Avatar
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    Try removing the power supply and then push and hold the power button for 10 seconds or more. Reconnect the power brick and try to start the PC.

    Jerry

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    Yes, Berton. It is the small box on the right. The brick puts out 12VDC and the motherboard must convert to the other DC voltages. Anybody knows if there are test points on the board for the voltages? I suspect that BATcher may be right and some voltage converter died. I tried Jerry's trick holding the on switch pushed--nothing. There is an amber LED at a corner of the motherboard marked AUX-LED. It can only be seen if you take the box cover off. It is not on. Is that LED supposed to be ON even when the computer is off?. That may be another indicator that the DC power is hosed.

  8. #8
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    Voltage regulators have failed on the motherboard. One thing to look for is if the capacitors are swollen or leaking. This was a common problem with a run of 620's. Dell had a swap out program way back with replacement motherboards. One big problem the USFF had was that after a power surge the brick would be dead. Also those little boxes had heat problems in enclosed areas. One of my departments got into them heavily and suffered. I replaced them with SFF and SDT because the P/S was inside the case and was more tolerant then the bricks (and not a nuisance). Back to you though....you have a dead motherboard...fixing it or replacing it would not be cost effective IMHO. You can find a nice Opti 960 for around $150 on eBay that has a dual core for more performance than your 620. I have one 620 tower left (personally) that soon will be donated to our local Boys and Girls club to help them.

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    Thanks, garthbock. I did check the caps, at least the big ones, and they all look good. But I agree that something in the DC power on the motherboard failed even though nothing is apparent. The brick is good because it works with other 620 units. Can you figure out what the amber LED that is located on the motherboard in the front left corner near a large cap and marked AUX-LED is suppose to indicate?

  10. #10
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    Quote Originally Posted by j-norton View Post
    Thanks, garthbock. I did check the caps, at least the big ones, and they all look good. But I agree that something in the DC power on the motherboard failed even though nothing is apparent. The brick is good because it works with other 620 units. Can you figure out what the amber LED that is located on the motherboard in the front left corner near a large cap and marked AUX-LED is suppose to indicate?
    The AUX-LED is the 'standby power LED'. If it's not lit, the motherboard is not receiving any power at all. The problem is most likely that the power inverter has failed. Some of the smaller caps on those motherboards (there were 3 or 4 different motherboards for the GX620 USFF) are only rated at 85 degrees (oops!). Those caps would heat up (too much) over time and dry out. There wouldn't be any signs of bulging or leaking caps.
    Those motherboards were made by various companies to Dell/Intel specifications, and were branded as Dell's.

  11. The Following User Says Thank You to sirpaul1 For This Useful Post:

    CLiNT (2015-01-28)

  12. #11
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    Right on sirpaul1

    I think that you are right on, serpaul1. When I first opened the case, it was chuck full of dust so it must have run hot. Attached is a photo of the motherboard and a close up of what I think may be the inverter that you mention (the thing with the spiky heat exchanger). There are 11 large caps around it. I would like your thought on the viability of replacing the caps to try to bring this machine to life.
    Attached Images Attached Images

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    Thanks to all of you for your help and advice. I shipped the motherboard to Chris at badcaps.net and he replaced about a dozen of the large caps. The PC is up and running again ready for a second chance at life.

  14. #13
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    What sort of cost? Is it worthwhile given the cost of secondhand hardware?

    cheers, Paul

  15. #14
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    The charge was $85 which I think is reasonable. It breaks down roughly, $30 for parts, $30 for labor and $25 for shipping. I prefer repairing to buying used hardware because this baby has been with me from birth. I know where it has been for the past 9 years and it is configured exactly the way I like it.

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