PC power supply acting up. - Page 1
Forum section: electronics / projects

author: tubos
author_rank: Contributor
timestamp: September 01, 2013, 03:01:41 pm
content: I'd like to repair this switching power supplythese are the (strange) symptoms.- When i shutdown the computer after powerdown it starts back up and powers down continuously.( from here i flip the main switch to stop this)- When i turn on the computer (with the big switch) it goes to the same stage over again until i pushthe power button at the right time ( took a lot of testing) and then it starts up and works normal .Any ideas on what i should check first?-Some background info :-No extra hardware is added that could overload the powersupply-Age of the computer / supply is 3 years-Once it starts up the power supply can work for hours on end without problems.thank you,

author: Unknown
author_rank: Unknown
timestamp: September 01, 2013, 03:14:49 pm
content: What makes you think this is a power supply problem? Did you get the same symptoms with a different power supply?I would check both the mainboard and power supply for leaking/bulging electrolytics.

author: shailesh3t
author_rank: Regular Contributor
timestamp: September 01, 2013, 03:47:23 pm
content: i think the problem is your operation software not your power supplytry to reinstall your OSregardsshailesh

author: tubos
author_rank: Contributor
timestamp: September 01, 2013, 05:30:37 pm
content: Its certainly not an os problem becausing the restarting occurs before the os has started.I assumed it was a supply problem , i have not tried another supply.I have to time exactly when to push the power button (when i hear a certain plop sound)otherwise it does not startup but stays in the loop.

author: SeanB
author_rank: Super Contributor
timestamp: September 01, 2013, 05:41:03 pm
content: I would open it and check the standby supply inside for bulging caps, as that is likely what is happening. You can replace them all, or replace the supply. Generally you will find a few 1000uF 16V capacitors there that are either bulging or have shrunk the sleeve around them. If that is so then the rest of the capacitors are likely to be on the way out as well, and either you replace them all or buy a new one. New is probably cheaper. Likely to be Capxon or another cheap Chinese brand capacitor there.

author: kizzap
author_rank: Unknown
timestamp: September 01, 2013, 11:16:30 pm
content: First thing I would do is verify that it is indeed a power supply problem as others in this thread have said.Take the power supply out of the PC, then on the large connector, short the green wire to any of the black wires on the connector. This should turn the power supply on. Verify that it is on. Then disconnect the short from the short to see if the power supply turns on and off as you described. If it does, then continue troubleshooting the power supply as intended.However from the description you have given, I would be investigating the on/off switch that you are using for the case, as it sounds like it might not be a momentary switch, and is latching on, which would cause the PC to turn on and off like you describe.-kizzap

author: ben7
author_rank: Contributor
timestamp: September 07, 2013, 07:00:16 pm
content: Bad capacitors. VERY common, and the symptoms are exactly the same as yours.