Sonata III case prob, or something else?

[astevens0691]

Sigh. I was a superpc graduate for a whole five days.

Last night, turned off the working pc, disconnected external stuff, and moved pc and peripherals to another room. Reconnected everything, turned the electricity back on, and tried to turn the pc on. Nothing. Dead as a door nail.

The monitor is receiving power, the speakers are receiving power, the surge protector says it is good to go.

Plugged the pc power cord into different outlets on the surge protector. Think I tried every outlet. Monitor, speakers, and surge protector indicate they are getting power. The pc, nada. No fans, no lights, no post. Took a second pc power cord from a working pc, and retried all the outlets in the surge protector. Repeated, turning the power supply on and off from the back of the case for each attempt. Nothing.

Next opened the pc case, moved the hd so I could jiggle the wires from the power and reset buttons. Reconnected the 24-pin cord from the power supply to the mobo. Pushed in all the other connections. Nothing disconnected.

Turned on electricity again. This time, when the power supply is turned on from the back, the case fan turns. The cpu cooler fan does not run. Tried pushing the power button and reset button on the front of the case while the case fan was running to see if it would turn off. It did not turn off. It remained running until I turned of the power at the back of the power supply.

So, what could cause this? Power and reset button problems, power supply problems, or a newly fried motherboard?

This pc was built with the following specs:

Antec Sonata III case
Antec Earthwatts model EA-500D, switchable, 500 watts maximum

GA-G41M-ES2L motherboard with boxed Intel pentium dual-core processor chip and cpu fan
4mb Kingston ram, speed compatible with motherboard and processor
Western Digital Caviar Green sata 640gb hard drive
Liteon dvd/cd combo r/w sata drive, used atapi
Windows XP home with service pack 2 in retail box-- comes on a cd

Arrgh.

[rexh]

Make sure that you don't have an extra mobo stand-off shorting out 24 volt supply under the mother board. Moving it may have gigled the mother board just enough to make contact. I had a similar no post issue when I built a system with a Sonata III case, I went back and found that I had left an unused stand-off in place and it was shorting out the mother board and power supply.

[astevens0691]

Thank you for this idea. This had never occurred to me, so it is a really valuable suggestion!

[zburns]

You would think that the ATX specification is very tight in the sense that an ATX mobo and an ATX case would only have matching holes for mounting, standoffs, etc.; however, after reading or rather "scanning quickly" the ATX development history (wikipedia) that may not be reality.

However, if you have an ATX mobo, and the only standoffs you have in the case are the ones that line up with the mobo mounting holes, then you do not have a "short" possibility from standoffs because the mobo mounting holes will have plenty of "clearance" from hot voltages.

If you have one or two extra standoffs in addition to the "matching" mobo mounting holes and their respective case standoffs, then a short would be possible. I am probably saying the same thing Rexh has said in his post.

Suggestions: 1. Using your mobo book and the Antec pamplet, disconnect the small plugs "on the mobo coming from" the Antec front panel. If you have a continuity meter, check the plug from the momentary on/off push button to see if the front panel wiring and push button are ok. Assuming all this is ok, do the following in the next para. --step 2. Note the late edit in quotes "on the mobo coming from".

2. With all wiring/plugs from the front panel to the mobo disconnected, you should know by now which two pins on the mobo are for the front panel on/off switch. Take a jumper, hook one end of the jumper to either of the two pins, then momentarily touch the other jumper end to the other pin. This action simulates your pushing the on/off button.

If everything works under this condition, your front panel is the problem. If the problems remain the same, then you have mobo or PSU problems.

When you do the above, it would be best to have everything disconnected from PSU except mobo, PSU, HD and one stick of RAM. Disconnect video card, DVD, etc.. Also, make sure that the PSU plugs on the items remaining in circuit are firmly pushed together. Any plugs into mobo should be firmly in place. Probably you should remove the video card from the mobo. (edit)

Warning: In step 2, for example, unless you are absolutely sure which mobo pins are the on/off pins, do not do what I say. First use your mobo book and antec pamplet to make this determination; if you cannot do this for whatever reason, call Antec tech service and ask about the case on/off switch, how many wires, which ones, etc.

I apologize for "lecturing" but the only way to troubleshoot is one step at a time and "only if" you are certain of what you are doing! This is just "natural caution". It takes much less time in the end to double and triple check always!

[astevens0691]

Thank you very much for your wonderfully clear suggestions. I appreciate them very much, and will try them as soon as possible. The budget just 'busted', so it may be a while before I get to spend money on this pc again. Sigh.