Power issues

When I tried to turn my computer on this morning, it came on for a few seconds, and then shut itself back off. It would not come back on until I unplugged it and replugged it back in. This is not the first time this has happened. The computer is an IBm netvista 6790 21u, 1.8 ghz running windows xp professional edition. The only recent changes to the system is a memory upgrade from 256 to 512 mb, But the power issue has happened before the memory upgrade. How do I find out if this is a failing power supply or something else?

The power issue is not happening every time the computer is powered on just sometimes. Any suggestions would be greatly appreciated.

 

Hi,

First thing I would do is replace the CMOS battery. You say it starts, then shuts down. The BIOS may be losing it's settings or making the wrong the settings and it shuts down becuase they are wrong.

You could be right about the power supply. If you have USB or other equipment connected, try removing/disconnecting them, if it is a little more reliable that could mean a failing power supply. I just borrow a power supply from a similar computer to try, but that may not be very easy for you. If it is the power supply, check it's dimensions and if you might need to order one from IBM.

1.8Ghz is getting a little old now. Rather than buy new parts for something that era, I think I would save towards a new machine or look for a similar one and see if I could make something even better (additional RAM, or a second HDD maybe). My 1.8Ghz had 256MB of RAM to start with, it now has 768MB, has had two or three different power supplies, runs 2 HDDs , a CD-RW and CD-ROM, just from broken or redundant machines I have come across (if I can't fix it, it gets assimilated )

There may be voltage readouts in the BIOS/Startup settings. Everest in my signature may be able to read them.

Check fans are spinning freely (including the one in the power supply). Do you clean the dust out of the case regularly?

I work on some older IBMs and they still run well. IBM have an excellent knowledgebase, so look up your model at their website and look through the FAQs. You might find a lot of other interesting facts about your computer.

Matt

 

If this is the Mini Tower Case I had one of them and I could not find a replacement PSU as they are a very small unit not a standard size at all I have 2 with blown caps and changed the mobo to upgrade but the PSU could not handle it.

 

It is not a tower, it is a desktop case. I cleaned out the dust when I added memory. The fans seem to be spinning properly. (TinyTuba's mom here, resident computer geek, but still learning some of the hardware related problems)

Will try the cmos and see if that helps. I have never changed a power supply before so may have to do a little reading on that. will try Everest to see if that gives a few answers or just more questions,lol.
If it was the cmos battery wouldn't it be losing other information like the date, time etc?

 

Hi mva5493,

Changing the CMOS battery is somewhat of a "maybe ". It may be at a stage where it is low, but not completely dead. A new battery is only a few dollars and I would prefer, although maybe not likely, but if it was a cause, I had not spent a large amount of time checking other areas. It is something I rule out when there are startup problems.

It does actually start and I expect it is the BIOS that finds that something is wrong and shuts the computer down (the motherboard/BIOS should control startup and shutdown). It could well be a motherboard problem. hawk22 traced his problems to the motherboard ( "caps" are the capacitors and they are the cylindrical components that stand up off the motherboard, check them for swelling or leakage).

Watch the drive LEDs, if you see them flash, it could be a problem with a drive.

The computer turns itself off, which is different to just stopping with the power on and a blank screen. It does not shut-down or give any problems during full operation? I don't think I would suspect the power supply first, but I would not rule it out.

Matt
PS In Everest, look under Computer/Motherboard for Sensor. Take it as a guide, because there are many factors that could be involved. The fact that the computer is OEM (IBM) is one of them.

 

Hi Matt,
have been away from both machines a bit sorry for the delay in responding. Holiday you know....I have changed the cmos battery and did install everest Under the motherboard/sensor the cpu temp is 25c (77f) and the ibm ic35l040avva07-0 is 46c (115f) Also under dmi, don't know if it means anything or not but it says boot up state is safe, power supply is safe, and thermal state is safe. Not noticing any immediate changes since changing the battery but will continue to monitor and report back anything that comes up. Also checked the motherboard for leaking or bulging caps, didn't see anything out of the ordinary. No leds flashing other than during the bootup sequence. No post beeps either. The only other issue noticed is that she cannot automatically update windows using ms update, has to be done manually. And symantec will not automatically run scheduled system scans, she has to do those manually as well and also noticed that under the windows security center symantec is disabled. I don't think that the symantec issues are a hardware problem, but I am reporting just what she is telling me. I think more information is better than not enough.

 

That's a good update You are looking past the initial symptoms. [Trust your holidays are going well ]

The temperature readouts appear good. The identification of the second sensor (ibm ic35l040avva07-0) is a little...errm, so definite conclusions may not be able to be drawn. 46*C is not bad. Check it again after the system does some "work ". That sensor appears to be the system temperature, it will relate to a general "throughput" of air in the case. Just check that air intakes at the front of the case are clear of blockage (even the keyboard being pushed up against the case).

Not a big deal. More than one beep would be something to worry about. I am hoping the change of CMOS battery may return things to normal.

During the normal startup sequence? The test will be when it has an abnormal startup sequence. Do the LEDs flash then and does one happen to stay on?

Any happenings in Windows will not affect the system/computer startup. Windows is not loaded at that stage (before you see any sign of the Windows loading screen).

If you hear that it is "doing it again ", try starting it yourself and watch what is happening. Second-hand (or third-hand) descriptions may confuse all of us. Go through the startup sequence with TinyTuba822 when it might happen. Point out to each other the areas of note. TinyTuba822 seems to be a very fine apprentice "resident geek ".

Matt

 

I guess we will have to wait and see what happens, everything in my last two posts have been things I have observed myself, but the computer appears to be running as it should for now, I guess I will monitor it during the next couple of weeks (TinyTuba is home on break, she is a college student so her computer is only here during spring, summer, thanksgiving and xmas breaks) With my own experiences with computers, I don't think we will get lucky enough for it to just be a cmos battery change, but we can always hope. Thanks for the advice and long distance diagnostics.