help with son's pc

[Carbon Dudeoxide]

   Too many self proclaimed computer *experts* have zero electrical knowledge.  Routinely recommend replacing parts on wild speculation because shotgunning only what they understand.

We're not electrical engineers, and nor are the people we're trying to help.

You demonstrate no electrical knowledge.

You demonstrate ignorance.

[westom]

(If you have more than one RAM stick, switch them around and try different slots on the motherboard)

Replacing RAM will report nothing useful.  If one RAM is defective, system will simply ignore it at the start.  And BIOS would report the defect on video.  System does not even look at RAM until after messages are put on video.  Your system does not even do that much.

  Removing RAM is another example of 'try this and try that'. Analysis by wild speculation. Removal can only report something if the motherboard speaker beeps.  Based upon a previous post, you are not even getting beeps.  That means the CPU never even looks at memory.  Maybe because the CPU is not getting permission to start?  CPU cannot start until given permission to do so.  Again, another unknown also answered quickly by 30 seconds with that meter.

[westom]

We're not electrical engineers, and nor are the people we're trying to help.

Nobody who used the multimeter need be an engineer.  Even first year auto mechanics use the meter.  A tool about as complex as a hammer.  And a tool used by anyone who knows how computer work.

  You again demonstrate fear.  Fear directly traceable to minimal if any technical knowledge.  With minimal knowledge, you would know memory has nothing to do with the OPs computer failure.

  OP has defined a classic problem where the CPU is not even permitted to operate.  Memory is not even involved.  So, tell us the many things that can halt a CPU?  You don't even know that.

Meter can identify what causes a CPU to remain halted - in 30 seconds.  Removing memory does not.

[svscofield2]

When I tried to check the pc, I did switch the position of the 2 ram chips.  I didn't have the mouse or keyboard plugged in.  I don't know enough to unplug the dvd-rom.  I moved it to another room and plugged it in.  I had the same results as before.  I am not confident enough to buy and use a multimeter.

[westom]

I am not confident enough to buy and use a multimeter.

I cannot be blunter about this.  If the meter scares you, then far more dangerous and complex is jump starting a car.  If you fear the meter, then never replace an AC plug - which is far more dangerous.

  Good reasons for multimeters even sold in K-mart.  Meters are so complex that only K-mart geniuses can use them.  Again, I am not kidding.  A meter is about as complex as a hammer.  Set it to the range (20 VDC).  Touch leads to anything inside the computer.  Read number.   You don't even need band aids for a smashed finger.

  RAM is completely irrelevant to your problem.  You have two choices. 1) Get the meter to have an immediate answer.  2) Or just keep buying and replacing parts until something works.

  The first solution means replies will also teach how computers really work - how simple some of that stuff really is.  The latter will costs big bucks and teach you nothing.  Do you entertain foolish fears?  Or fix it fast and the first time ... and learn something?

  Meter is sold even in Wal-Mart for less than $18.

[Carbon Dudeoxide]

Jesus Westom, the OP doesn't want to try it. I don't blame him/her. Deal with it.

Svscofield2, when you press the power button, what happens on the screen?

Also, how old is this computer? Is it a pre-built computer? (from the store?)

[luck of the irish]

OK,

First of all Westom, what if the user accidently touches an electro-lytic capacitor with the negative leg touching the positive cable of the DMM, that could cause the capacitor to blow, causing the MoBo to malfunction. To me, it sounds like a faulty hdd, did you disconnect harddrive? leaving in graphics card?

[camerongray]

I do remember seeing in the manual for an old (486, Windows 3.1, 1992) computer that unplugging the PS2 (Round Plug) Keyboard and Mouse could "cause serious damage to the PC."

Was the PC on when the mouse was being replaced?

Not sure if modern PCs are immune to this problem though.

[svscofield2]

This is an older pc from around 2004.  The case has no name on it (husband thought it was a vcr from a distance).  The pc was on when son unplugged the mouse.  As to what happens on the screen when pressign the button:  there is nothing at all on the screen, just pitch black.

[svscofield2]

here some numbers I managed to find on this pc
sink fan:  avc model c4010t12h
larger chip:  VIA VT 8231  0306cd  13h011200

case:  p/n 91.96320.hol  s/n 31224655 lp aa

power supply also has the case number plus p/n04300.h22 s/n 30900160 lw r01

also found EPEA REV.D on the motherboard

[svscofield2]

make that epia not epea...sorry

[svscofield2]

apparently it is an epia mini itx motherboard

[westom]

As to what happens on the screen when pressign the button:  there is nothing at all on the screen, just pitch black.

 So memory, another mouse, and all those other 'try this and try that' ideas will not help.  Are completely irrelevant to your symptoms. Either get the meter to do what a junior high school science student can do.  Or take it to a computer repairman who will do the same thing.

  Age of the PC, those part numbers, etc report little that is useful.  What is problematic and what the meter will report is essentially same on any Pentium computer (with minor detail differences that are irrelevant here).  All you need do is take measurements.30 seconds of labor with zero risks. Then the few who actually have advanced knowledge will reply accordingly.

  If you fear using a meter, then you have no business swapping memory or doing other things that are potentially more dangerous.  For example, when you removed memory, did you first disconnect the AC plug?  If not, you have put hardware at risk.  Why?  Those meter numbers would make that obvious.  Potential hardware damage and other complications is why to probe with a meter long before swapping or shotgunning anything.

  If you fear using the meter, you have no business trying something more dangerous to the machine.  Take it to the shop.  If you want to fix it and learn, get the meter.

[BC_Programmer]

OK,

First of all Westom, what if the user accidently touches an electro-lytic capacitor with the negative leg touching the positive cable of the DMM, that could cause the capacitor to blow, causing the MoBo to malfunction. To me, it sounds like a faulty hdd, did you disconnect harddrive? leaving in graphics card?

And what if somebody accidentally spills a orange soda onto the motherboard? And how does a HD defect cause a capacitor on the video card to blow?

I'd say test the PSU output. This is a safe procedure; quite well documented in several PC repair books; if I may quote:

1.Check the AC power input. Make sure the cord is firmly seated in the wall socket and in the power supply socket. Try a different cord.

2.Check the DC power connections. Make sure the motherboard and disk drive power connectors are firmly seated and making good contact. Check for loose screws.

3.Check the DC power output. Use a digital multimeter to check for proper voltages. If it's below spec, replace the power supply.

4.Check the installed peripherals. Remove all boards and drives and retest the system. If it works, add items back in one at a time until the system fails again. The last item added before the failure returns is likely defective.

I think we've eliminated the other issues- and why would it be in a PC repair textbook if it was dangerous/unsafe, anyway?


Not sure of this was outlined anywhere but it goes on to specify what should be measured and how to go about it (backprobing).

To measure voltages on a system that is operating, you must use a technique called back probing on the connectors You can't disconnect any of the connectors while the system is running, so you must measure with everything connected. Nearly all the connectors you need to probe have openings in the back where the wires enter the connector. The meter probes are narrow enough to fit into the connector alongside the wire and make contact with the metal terminal inside. The technique is called back probing because you are probing the connector from the back. You must use this back-probing technique to perform virtually all the following measurements.


To test a power supply for proper output, check the voltage at the Power_Good pin (P8-1 on AT, Baby-AT, and LPX supplies; pin 8 on the ATX-type connector) for +3V to +6V of power. If the measurement is not within this range, the system never sees the Power_Good signal and therefore does not start or run properly. In most cases, the power supply is bad and must be replaced.

Continue by measuring the voltage ranges of the pins on the motherboard and drive power connectors. If you are measuring voltages for testing purposes, any reading within 10% of the specified voltage is considered acceptable, although most manufacturers of high-quality power supplies specify a tighter 5% tolerance. For ATX power supplies, the specification requires that voltages must be within 5% of the rating, except for the 3.3V current, which must be within 4%. The following table shows the voltage ranges within these tolerances.


To test a power supply for proper output, check the voltage at the Power_Good pin (P8-1 on AT, Baby-AT, and LPX supplies; pin 8 on the ATX-type connector) for +3V to +6V of power. If the measurement is not within this range, the system never sees the Power_Good signal and therefore does not start or run properly. In most cases, the power supply is bad and must be replaced.

Continue by measuring the voltage ranges of the pins on the motherboard and drive power connectors. If you are measuring voltages for testing purposes, any reading within 10% of the specified voltage is considered acceptable, although most manufacturers of high-quality power supplies specify a tighter 5% tolerance. For ATX power supplies, the specification requires that voltages must be within 5% of the rating, except for the 3.3V current, which must be within 4%. The following table shows the voltage ranges within these tolerances.

Code: [Select]

              Loose Tolerance Tight Tolerance
Desired Voltage Min. (–10%) Max. (+8%) Min. (–5%) Max. (+5%)
+3.3V         2.97V         3.63V         3.135V         3.465V
+/–5.0V 4.5V 5.4V 4.75V 5.25V
+/–12.0V 10.8V 12.9V 11.4V 12.6V

The Power_Good signal has tolerances that are different from the other voltages, although it is nominally +5V in most systems. The trigger point for Power_Good is about +2.4V, but most systems require the signal voltage to be within the 3.0V to 6.0V.

 Replace the power supply if the voltages you measure are out of these ranges. Again, it is worth noting that any and all power supply tests and measurements must be made with the power supply properly loaded, which usually means it must be installed in a system and the system must be running.

[svscofield2]

When I did the ram swap  not only was the pc not connected to an outlet, it didn't even have a power cord attatched.  When I was in high school, science was an elective so I actually did not take any classes.  We didn't even have computers for our typing/business/keyboarding classes--we used IBM selectic typewriters.  In college I had basic science classes, still nothing related to electronics or computers.  I don't even own any computer repair books.  I look up the information on line or save the money  so that I can take my computer to a repair technician. 

Westrom, can I ask a personal question:  am I being too sensitive when I feel as if you are ridiculing me for not being comfortable using a multimeter?  I used something similar, I suspect, when I hooked up my cb radio back in the 1980's.  I came to this site looking for assistance, not ridicule or insults.  I am genuinely looking for help here.  This computer is what I use to ease the stress my son is feeling with school being out for the summer.  He is severe ADHD and the disruption to his "normal" schedule has him rattled. I need to get it up and running ASAP.