Electrical storm damage?

[Odyssey]

Following an electrical storm, a computer which was unfortunately plugged in at the time, now doesn't start up. The on/off switch may also be faulty.

Tested the PSU with a PSU tester and it shows to be OK.

When it is first plugged in, the cpu fan comes on for 2-3 seconds, then goes off. Occasionally this behaviour can be duplicated using the off/on switch.

No beep at all.

CPU or mobo fried?

 

[edfair]

Possibly M/B. Most I've seen like that had problems with the line drivers/line receivers. Pull your drive cables and try again. Sometimes a problem gets through to the opticals and shorts their power circuits out.

If it was a direct short I would expect a 1/2 second max till shutdown. You could also have a processor fan issue, shutdown from lack of revs is generally 2 to 3 seconds.

Power up switch shorting generally leads to a 5 second shutdown.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[BadBigBen]

Tested the PSU with a PSU tester and it shows to be OK.

Try another known working PSU, PSU testers do not check draw...

I've had a PC (Dual Xeon system), that would POST and you could install XP, all went fine until the final reboot (where it activated the second CPU, this is where the DRAW comes into place) and shutdown, took me a whole week to figure that one out...

and what Ed pointed out, that sometimes the problem is HDD/ODD, pull the cable on the mainboard side, some controller detect cables and will behave abnormal when nothing is attached to the cables...



Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[Glenn9999]

Electricity is a funny thing. When a power surge happens it usually takes out the PSU, but can take out any number of things on a computer, depending on where it comes from. In any place. It can also either take something completely out or just make it so it doesn't quite work so well (random hardware induced crashes), yet it works.

It makes it hard to troubleshoot. Every computer I've ever encountered that's been involved in a lightning/surge related mishap has always been among the more difficult to troubleshoot.

You need to check (and if you can swap) every component, starting with the PSU. I suggest you cut the power to any extraneous components (stuff the computer doesn't need to boot up) as you start this testing and add them back as you prove the prior components work.

Measurement is not management.

 

[edfair]

Or some of the easiest when the tops of the line driver chips were blown off.

To add a comment, when you have that type of damage there is generally a pungent odor remaining for weeks. Give it a sniff test.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[gbaughma]

Heh... I always found it interesting when people would ask me about "Lightning Protectors"

I'd hold my fingers about 1/2" apart, and point out "This is about how far the leads are on the protection circuit. You think that after jumping 4 1/2 miles through the atmosphere, that another 1/2" is going to stop it?"

While surge protectors will offer protection against transient surges (stuff that happens, for example, when you plug your vacuum cleaner into the same outlet as the computer), the best protection that surge protection offers is their "Equipment replacement guarantee".

Additionally, most power surges DON'T come in through the power lines. More people are killed while on their house phone from a lightning strike, because those wires don't go through transformers, a breaker panel, and a surge protector before getting to you. I once saw lightning that had struck a phone line go through the computer, through the speaker output of the sound card, and blow up a receiver attached to the computer.

Another lightning strike I saw on a phone line blasted the phone off of the wall, and the cord that was running up the wall looked like detonated primer cord... nothing left of the cord, just a charred black outline where it used to be.

Anyway... enough stories... the next thing to do (as stated) is to unplug all drives, remove any un-needed cards (network card, modem, USB Devices, etc) and see if the system boots. If not, the least expensive thing to try next is the power supply. If that doesn't work, then it's the mobo/processor.



Just my 2¢

"What the captain doesn't realize is that we've secretly replaced his Dilithium Crystals with new Folger's Crystals."

--Greg

http://parallel.tzo.com

 

[edfair]

A small correction Greg. Phones do have their own surge suppressors, a set on either end of the phone line. Totally inadequate for what we need them to protect but sufficient for the telephones in service in the early 1900s. And subject to issues that create strange happenings in the phone service.

When I was designing power stuff we got a feedback from an insurance company with a picture of the meter box 30 or so feet from the side of the house, where it came to rest.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[Odyssey]

Back now with a new ATX PSU. The cpu fan now runs for pretty dang close to exactly 5 seconds. With input from the person that uses this computer (to the effect that the front panel on/off switch might be dodgy), combined with edfair's post, points to a bad switch.

How do I "bypass" the front panel switch to be sure? Seems to me there is a way to short 2 of the leads to one of the mobo connectors, but I don't remember.

If it is the front panel switch, my experience is that the damn things are next to impossible to get to and replace, or do I have that wrong?

Is there a way to just use the on/off switch on the PSU to turn it on and off?

 

[edfair]

Suspect that it points to the motherboard and the control circuits for the power supply.

The power on impulse is closing a normally open switch across 2 pins of the offboard connectory. Testing requires you to pull the power up switch connector and short the pins with a screwdriver blade. That should bring up the power supply.

Were the switch shorted you probably wouldn't get anything up as there wouldn't be a voltage transition available to activate the latch circuits.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[Sympology]

Yup my Meridian Option 81 story (Big PBX).

Lightning managed to somehow enter a copper ISDN 30 line, left the NTE equipment intact, left the ISDN card in the PBX intact, but fried the analogue card and several phones.

The moral of the story, it may not be the first part in the system that gets affected by a strike.

Most people spend their time on the "urgent" rather than on the "important."

 

[Odyssey]

Back to the problem after an extended interruption. Shorting the power posts has exactly the same result as if the front power switch leads are connected and turning on the switch on the PSU:

5 seconds of cpu fan, no video and no beep

What next please?

 

[edfair]

M/B time.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[Odyssey]

Other than substituting a known good motherboard (then the CPU) to see if it will boot up, is there a way for a individual to determine which (or whether both) might be bad?

 

[edfair]

There are some diagnostic tools that can be used:
Post diagnostic cards that show where boot fails,
Logic probes to see the activity on address and data lines,
Oscilloscope to look at the voltages present, and
VOM to look at the power supply levels

You are at a situation called "between a rock and a hard place". Substituting either may blow a new part.

If you have all the offboard stuff pulled, have pulled the battery for 15 minutes or so then replaced, and it still doesn't give any indication of processing you would need a logic probe at least to see if the processor is cranking. And even then you wouldn't know if it was right or wrong.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[BadBigBen]

Taking out the Battery for a prolonged time is good advice, this will clear the CMOS area (which could have become corrupted but not detected by the logic of the BIOS)...

also I've seen PC's that would not post, after a storm even when I changed the PSU, until I reset the PSU/Mainboard... it is a shot, but worth it: pull the main power to the PSU and hold the PWR Button for more than a minute, then hook it back up and attempt to POST...

other than that, it is the way Ed mentions on how to be certain that something failed, between the mainboard and CPU...

Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[Odyssey]

To recap:

All cards, memory, power connectors were removed and carefully reseated

There was not then nor is there now any smell of fried circuits

The PSU was replaced with a known good unit, which resulted in the CPU fan start up/power down cycle going from 2 seconds to five seconds. Still no beep.

Mobo with CPU and RAM removed, placed on a cardboard sheet and connected to the good PSU, monitor (through video card), KB, mouse, then shorted across power connector. No change.

Finally borrowed a stick of RAM to replace the original, and voila! Boot up!

However, I still have the issue of the faulty front panel switch. Is there any reason why I cannot cut the pair of wires to the front panel switch and add a new switch of some sort which will serve the purpose? If OK, what kind of switch do I need-just one that momentarily closes, similar to a doorbell switch? Are there size or voltage issues of some sort?

 

[wb5pev]

The other thing to look at with any lightning damage is that just because you get it to working today does not mean the all damaged parts are gone. That is unless you replace everything. In the Two-way Radio field which is where my main job is, anything that has been damaged is best off to be just replaced. CMOS does not like high voltage.

 

[BadBigBen]

The switch in use is a MOMENTARY switch, and I see no reason why you could not just add another switch...



Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[edfair]

Temporarily you could use the reset switch if there is one on the front panel. Both are normally open, momentary contact for the duration of the press.

Replacing a switch can be an exercise in frustration. There are more kinds than I have fingers and toes to count and locating an exact replacement can be like looking for the proverbial needle in the haystack.

But to answer the question, any single pole, normally open, momentary contact should work. You could cut the wires and splice in another switch. You are dealing with something that switches 5 volts DC, at something like 20 ma. You may end up hanging the switch outside the box since most recent cases use switch mountings that don't match what is available for replacement.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[Odyssey]

Thanks all. I may even have an old case in the attic that should have been binned some time ago that I can salvage a switch from. The computer is back at the office, but I'll try the reset switch to see if it will do the job.