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T7400 Won't power on
Here's a weird one:
This has happened before but it's been so long since it last did this - years - I don't remember how I've fixed it. This T7400/Win 7 works fine as long as power is never interrupted but my UPS battery failed which killed power to the machine. As has happened in the past, now, it won't power up:
- No front status lights work so no diagnostics
- The amber motherboard light works when power is connected
- Power Supply BIST switch works like charm. Yes, I've tried powering on while alternately pressing the bist
- Tried the power button (everything disconnected) reset method several times
- Tried disconnecting all installed devices including RAM, plugging and unplugging the machine
- Replaced CMOS battery which was overdue anyway
- System doesn't do the typical fan startup/power supplied thing when being plugged and unplugged which is a telltale sign of some kind (idk what though)
- Yes I considered replacing the power switch assembly but ...
The last time this identical problem occurred it turned out the PSA was fine. In looking at this list of symptoms, none of them seem related to how I normally get it running. It's got data onboard I need - no can't just yank the drives, it's 4 hds, RAID 10.
Thanks for any useful ideas!
bradthetechnut
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March 15th, 2020 15:00
Bad PSU or MB, more likely the PSU. Not unusual for idiosyncrasies to start before the PSU finally goes.
NeuroToxicHobo
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May 30th, 2020 13:00
I have a similar issue. If the power is interrupted, the machine will start up... fans go to high for a second, and then it shuts down. I have tried every diagnostic step and check possible but the only thing that works for me is to unplug it... sit it in the corner for a few days and then check it a few days later and it will again work until the power is interrupted.
Hope this helps, as I have found nothing else that will fix the problem instantly in that moment.
bradthetechnut
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May 30th, 2020 15:00
Hi @NeuroToxicHobo,
You said it works again until power is interrupted. Are you having power outages?
Either way, it sounds like a PSU on it's way out. PSU's on the way out can fool people temporarily by working for a while, and then it's hard starting. Get out the jumper cables.
The machine temporarily running the fans when plugged in is normal, I'm not sure about on full blast though.
Since a low battery can cause all sorts of bizarre problems, and the PSU is controlled by the MB, I'd try replacing the size 2032 CMOS battery to make sure that's not it. Cheap fix even if by chance is doesn't work. They last around 5 yrs. T7400 goes back to 2008.
effu
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May 30th, 2020 16:00
HI and THANKS for the input,
So, as I described from past problems, the T7400 IS running again. I got it running by cycling multiple times with pressing the power button and plugging/unplugging the power.
I DID change the CMOS battery but it had no effect on powering prior to the above. Yes, we do occasionally have power outages and normally this PC is on an APC UPS however, it isn't possible to get replacement batteries due to shipping batteries, even though all other batteries, ARE air shipped in many instances ... go figure.
I don't think there is anything wrong with the power supply because EVERY instance where I press the test button, the system powers up in the test mode.
Very strange problem. I was using it as a file server but due to reliability, I've moved everything over to an R510.
But any further ideas are appreciated. Thanks again!
W
bradthetechnut
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May 30th, 2020 16:00
If you have to push the test button to show initial power, or keep it pressed so that the PC boots, that's still the PSU. If it were something else, chances are PC would not boot at all but give you error codes instead.
I don't know why some PSU's go out like that, but it's happened before in this forum.
I had a PSU do computer restarts. Didn't seem like PSU. That can be a sign of a virus instead. But eventually it died.
speedstep
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June 7th, 2021 19:00
Its a failing power supply. Given the age of this unit this is not surprising.
This is not uncommon to be intermittent.
When the failing component gets to hot it shuts off.
effu
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June 7th, 2021 19:00
Sorry Guys,
But as I said, after leaving it plugged in to power and cycling the front power button while plugging and unplugging the power cable, it eventually came back up, functioning perfectly. It's happened a couple more times since and the fix was the same. It's obviously NOT neither the power button assy or the power supply or it wouldn't work as I've described. It's almost as if something on the mother board needs to build up or see a certain charge/voltage before the system will power up - my half-fast idea.
Thanks!