computer smps problem

Hewlett-packard Compaq presario cq5320f...
August 11, 2010 at 02:37:47
Specs: Windows XP
When I turn on the power (wall socket) and the UPS, the SMPS 'ON' indicator (green LED) at the back of the CPU glows. But it goes off the moment I press the CPU power button and computer doesn't start. CPU is dead with no fan or indicator working. How to solve it?

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#1
August 11, 2010 at 03:17:23
However, after repeated trials to start the computer by turning off and turning on the power mains, the computer starts normally once in a while but suddenly the power goes off and computer restarts and power goes off again repeatedly. Turning off the power mains and the same problem as I mentioned in the first line. I opened CPU, air clened it and there is no apparent loose connection. Please help.

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#2
August 11, 2010 at 04:57:19
Will the computer boot and run normally if you connect it directly to the AC mains bypassing the UPS? If so, then the conclusion would be your UPS is defective. Perhaps the battery is worn out.

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#3
August 11, 2010 at 10:33:45
No, I tried to run it directly from the power socket bypassing the UPS but the problem is there.

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Related Solutions

#4
August 11, 2010 at 10:40:30
What do you mean the problem is there? Do you mean you get the same results with or without the UPS?

The light at the back you mention is probably the network card indicator light.

Even when your computer is turned off there is some power going to parts of it.

Did this same setup previously work? What happened just before things quit working?


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#5
August 12, 2010 at 08:40:51
Yes, I mean there is no difference if I use the UPS or connect it directly to the AC mains. The green LED at the back is not the LAN indicator but the one coming out of the PSU. So far I know, this LED should glow as long as AC mains is present to the PSU. Please help as I badly need it.

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#6
August 12, 2010 at 08:49:33
The same setup worked earlier and still working sometimes. But after I shut it down, I cannot turn on the power. Say I couldnot turn on the power in the morning, but surprisingly, in the evening it started normally and worked fine. Then the system is dead again in the next morning. A queer problem. ICan it be due to some dry solder? But i cannot guess whether it is in the PSU or mobo, if at all it is there. Any idea will be of utmost help.

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#7
August 12, 2010 at 09:04:03
normally you would start by replacing the power supply.

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#8
August 12, 2010 at 09:30:23
If the motherboard were faulty I would think it wouldn't run at all. It is possible to have a cold solder joint that could act as your computer does. That said, I would suspect the PSU first too.

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#9
August 12, 2010 at 09:41:19
agreed re' the psu (power supply)...

Typically if a device appears not to work initially but then does after being re-powered once or twice - or more - it can indicate dodgy electoryltic capacitors in the psu. These items "can" leak after a fashion; and a brief (initial) surge of power can seal the leak - for a while; and then the system will work OK - possibly until powered down and one starts the whole sequence again...

Likewise occasionally the scr/s (the rectifer/s which produce the dc volts from ac volts in) in a psu can go leaky too - although usually they just fail; as can a voltage stabiliser go intermittend/leaky - but again usually fails...

Overall I'd be inclined to either test/check volts out of the psu (with decent voltmeter; and presuming you are happy, and know where to look, and what to look for). Test/check psu volts with no load - nothing connected to it first; then connect to motherboard and recheck volts etc...Otherwise test system boot up etc. with a know good psu?

If the test psu fails to resolve it.. then problem is logically elsewhere?


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#10
August 12, 2010 at 22:36:52
Thank you friends. As suggested by u, I will try measuring the voltage at the PSU output leads one by one. I've got the ideal voltages through google. As I cannot test the PSU by swapping with another & have to buy one, I first try to locate the fault and replace if needed. Anyway, I'll inform u about the developments. More suggestions are welcome.

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#11
August 13, 2010 at 02:45:41
mmm in thd days of Compu$a... one could buy one and return it (having tested system with it) if not required (within a few days and in effectively good condition...?

Possibly BestBuy/Frys etc. may allow similar?


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