Power problem, or MB problem?

[sunspore]

Hi,
I'm working on an HP Pavilion 7960, trying to determine what the problem is. Here are the facts:

1)When the computer is turned on, the monitor does not respond at all. It's as if it's not hooked up to anything. I know the monitor is good because it works fine on another computer.

2)I have a mouse that lights up when it has power going to it from the MB on another machine, but when hooked up to the USB port on this machine, no lights.

3)The same problem exists with the USB keyboard: no lights when on this machine, whereas it has the typical keyboard lights when plugged into another machine.

4)At first I figured this was a problem with the power connection on the MB, as the video card and USB ports weren't getting the power to run their respective components. But then I noticed that the power light for the computer was on, and the system fan and CPU fan were running. All three of those things are plugged into the MB, and use power from the MB.

5)I believe the devices that plug directly into the power supply are working fine, as I can hear the hard drive spinning.

So in a nutshell, I've got some devices getting the power they need from the MB (power light, fans), and some not (USB ports, AGP video card). Could this be a problem with the MB not being able to pass power to certain devices, or what? What is the suggested remedy, or further diagnostic tests? Thanks for any help!

Drew

 

[edfair]

Sounds like the processor isn't running. USB would be a device turned on during post.
CPU or M/B likely causes. Would need a logic probe to see if address lines or data lines are active.

Ed Fair
Any advice I give is my best judgement based on my interpretation of the facts you supply. Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[sunspore]

thanks ed,

What is a logic probe, and how can I use one?

Drew

 

[edfair]

Test device you hook up to +5 and 0 on the M/B and touch a logic line. LED lights. Normal green +5, red 0, and switching back and forth for pulsing. You need to know what to expect to take advantage of all the capabilities, but just looking at a couple of bios lines should tell you whether the processor is clocking.

Ed Fair
Any advice I give is my best judgement based on my interpretation of the facts you supply. Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[jfryer]

Is it possible that both the USB and Video have been turned off in the BIOS?

I know that you can turn the USB off in most BIOSs and if you are using a AGP you can disable it, or perhaps you have onboard graphics and it has been disabled?

Problem here is how do you get into your BIOS to change something if you cannot SEE the BIOS!?! That I cannot help you with.

Its funny that most of your computer seems to be working but not the USB and video.

If your keyboard is not working you SHOULD be getting POST errors (all those beeps when the comp starts up)
in short
1 beep = good
2+ beeps = bad

How many beeps are you getting?

Another possibility (I'm just brain storming here) is that a jumper has been knocked loose from the motherboard. Some boards need a jumper set to enable/disable graphics (more specifically onboard graphics) and to enable/disable USB. have a look at your manual for the MB and see if such jumpers exsist for you, if they do I would advise that you check them.

hope it helps.

Let us know if you solve it.

-------------------------------------------
There is no magic, only onions
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[Eskimo69]

Well first check your power supply. Like switch your board to a different case leaving most periferals not conected or disconect devices and try a known good power supply. (This is what I do). Hold your finger on the processor and see if it is getting hot, (don't mistake hot for warm when it's getting juice you'll know it). Alot of older boards are toast with no visual burn marks or anything. Just shot. The setting to disable your USB and others is stored in CMOS which can be reset usually with a jumper but if worst comes to worst simply pull the battery.

 

[Eskimo69]

I thnk I have some sharts of post beep errors. I could scan and send to you. Well I guess it wouldn't matter because it sounds like to me nothings working. (I've got and Idea, How about your fans are they turning on you might have one inside the case, You'll have one on the Chip and one in your power supply.) another good Question is did you get the power cables backwards.(I've done that,lol) the black wires should be on the inside of the connector.

 

[sunspore]

Yes, Eskimo, all the fans are working. Also, the CPU is getting hot. I don't get any beeps at all. It's a very confusing problem. Obviously, the MB isn't completely dead, but it seems that it is having some problems. I don't know what else it could be. I'm currently looking into diagnostic tools that could tell me definitively whether it's the motherboard or not. Any ideas? The connector is ATX, so it's just one piece, and it's been connected to the board since I got it.

 

[Eskimo69]

Jumpers maybe then. I know it's a pain but I end up doing it everytime I work on something I just search for the mobo specifically by manufacterer and model #, Not the computer like HP. and then I get the manual besides getting it to run. Things seem to run alot smoother if the jumper settings are exactly correct for what you have. Usually on power supplies you either have no power or power and if your fans are comeing on you have power, right? Here in a minute I'm going to look up the mobo I'm workeing on so I can figure out this ps2 problem.

 

[fin33]

I have one(9 in the house all together- 8 working) PC with USB mouse and keyboard -they will sometimes just stop working and I was restarting the computer to get them back then I found where they had broken connection on the motherboard that would make contact most of the time but not all the time. Long time ago had one that the power supply had broken stranded wires inside - it would lock up or stop working and sometimes come on and work fine. I love PC probs don't you???? Yeah right!!

 

[BadBigBen]

Hola, let me drop a few ideas into the fray...

1.) if the mobo has a jumpered FSB setting check it if it is set correctly for the CPU in use...

2.) try another PSU, PSU could be shot, ergo 12v and 5v lines working and the 3v line not...

3.) reseat RAM, loose RAM sticks can cause the symptoms you describe, better yet try another good working mem stick...

4.) unplug (from mobo) all IDE devices, power the PC on, does it POST? if yes, replace the IDE cable, double check if all IDE devices are jumpered correctly, before reinstalling...

5.) check if the CPU/Heatsink fan is functioning correctly, is plugged in correctly, some mobos will not power up without a proper CPU fan installed...

Ben

 

[bkd]

I had a similar problem when I updated the motherboard and CPU from PII 200 MHz to Athlon XP 2400+. The PSU was 250 watt, and fans and everything else seemed to work OK, but no POST. Changed to a high spec. ThermalTake 420 Watt PSU and now works OK.

 

[crazy888s]

I also had a similar problem where some devices would kick on but the computer wouldnt POST. I thought it was the processor, like edfair said, so i tried a new one and got the same results. In the end, my problem was my 300w power supply! I now run a 500 watt piece with no troubles...

 

[ceh4702]

I have seen with some video cards that there is sometimes Black background and black text at the same time. Windows comes on and the windows sound plays and you just cant see anything. But usually when this happens you can see the BIOS Boot screen then everything turns black. The solution is to go into safe mode by pressing F8 during boot.

Try removing the video card and reinserting it, and then plug the monitor back in. Might try the other cables and the RAM also. Sometimes you can get a slightly disconnected Data Cable on a hard drive or something like that. Rounded cable can be bad for this if you have 2 drives on the same cable and they are too close.

If you do not like my post feel free to point out your opinion or my errors.