Lightning!

My iMac Intel Core 2 Duo was plugged in recently when my house was struck by lughtning. It turns on, to a dim bluish/black screen and has the startup sound but no picture avail.

Is it possible that the iMac is completely fried? Or is it able to be fixed?

Think it's even able to be sold for parts?

sounds like the screen or GPU is fried

can you hook it up to another monitor or TV to see if the mac itself is booting properly

Does your insurance cover power surges?

Was it plugged into a surge suppressor (commonly known as a "power strip")?

It's really hard to say, but in my experience, lightning strikes often only damage the power supply. In the iMac, the power supply is built into the machine itself, so regardless of the extent of the damage, it would need to be opened and inspected to make a more certain diagnosis.

By the way, if you own your home and have Homeowner's insurance, it may cover the damage or replace the entire machine.

well would i be able to rule out the PSU if it turns on and i hear the chime or no?

harris.sullivan said:

well would i be able to rule out the PSU if it turns on and i hear the chime or no?

Click to expand...

No. There are multiple voltage rails on a PSU. It is possible, and very common, to have only partial functionality in a PSU that will cause a machine to act flakey, but still boot.

so how would i be able to really know what happened and what i need to fix without spending money @ apple?!

thanks guy btw

You can't and check the house insurance.

I checked in with my house insurance provider and they said that all they need is a letter from a certified technician stating that the machine malfunctioned and then they will send me a voucher for a new iMac! how sweet!

But on the other hand, I am going to attempt to salvage the current computer because there are still signs of life left in it; such as:
1. i removed the RAM, so when I start the iMac up the screen dims and there is a chime that happens every 3 seconds, signifying that there is no RAM detectable
2. The screen goes from being completely black (when OFF) to looking sort blue/black (resembling a black eye when ON) but then that is all.
3. Upon turning it on, 1 out of 3 times (guesstimate) the startup sound begins and the screen just stays dimly lit not doing anything.

Any suggestions as to what the problem was, or if it is even fixable?

Thank You

Go back and read cwa107 post on PSU. Get the insurance money first as they may want the carcass as they have paid for it.

regarding the PSU, is there anything I can do at home to try and combat the problem?

harris.sullivan said:

regarding the PSU, is there anything I can do at home to try and combat the problem?

Click to expand...

As Franklin demonstrated in 1752, surges seek earth ground. Why would you have appliance damage? That current found earth ground destructively inside your house. Protection is always about where energy dissipates. Either earth an incoming transient before it enters the building. Or that surge dissipated destructively inside - with or without interior protectors.

For over 100 years, surges have been earthed so that even telephone operators need not remove headsets during thunderstorms. The technology is that well proven and understood. If that transient was inside your building, then you have what an overwhelming majority do not have. No effective protection.

A direct lightning strike to wires down the street is a direct lightning strike to any or every appliance. An electric current that hunts for earth. The 100 year old solution is easy. Every wire in every cable connects to earth before entering the building (cable TV, satellite dish). Of course AC electric and phone will not work. So that wires get connected short (ie less than 10 feet) via a 'whole house' protector. Energy absorbed in earth need not hunt for earth via your power supply. It is that simple AND how it was done even 100 years ago.

What provides protection? The protector? Of course not if comprehending what was posted above. A protector is only a connecting device - not protection. Either is connects that energy to earth, OR may connect that energy destructively via an adjacent appliance. IOW a protector is only as effective as its earth ground.

How to avoid future damage? Have you upgraded earthing to meet and exceed post 1990 code requirements? Does every incoming wire connect short (ie 'less than 10 feet') to that single point ground?

The most common incoming transient path is AC electric. If you have not installed a 'whole house' protector, then surges can overwhelm protection already inside every appliance. Effective 'whole house' protectors only come from more responsible companies such as Square D, Leviton, Siemens, General Electric, and Intermatic. The Cutler-Hammer solution sells in Lowes for less than $50. A solution that costs about $1 per protected appliance.

What protects your furnace, dishwasher, and bathroom GFCIs? Only earthing and that one 'whole house' protector. Instead of spending tens or 100 times more money on plug-in protectors, the informed homeowner directs that money to better earthing. Bottom line - a protector is only as effective as its earth ground. And that answers your question.

And if you do intend to make a claim then do nothing until such time as it has been assessed.

As was stated, make sure you have a very good ground to all sockets. Purchase a surge protector with a replacement guarantee. That is, a high quality surge protector, not some dinky plug strip with "surge protection".

Years ago, I had a lightning strike directly on my tower. All that was left of the antenna was fiberglass shards and aluminum blobs. It took out all my ham radio gear and the attached computers. Including a very expensive surge protector.

I collected all the info on the gear, including some pictures, and submitted it to the manufacturer of the protector without much hope that the guarantee was real. It took a couple of months, but to my surprise, they sent me a check for what my homeowners didn't cover - which was most of it.

I have also had a couple of close strikes that cremated the protector, but didn't get through to the connected gear.

Again, the most expensive and technically superior surge protector is worthless without a very good ground. The better the ground the less chance you will have of disaster striking.

cptkrf said:

Again, the most expensive and technically superior surge protector is worthless without a very good ground. The better the ground the less chance you will have of disaster striking.

Click to expand...

Wall receptacle ground is a good safety ground and useless for surge protection. Stated repeatedly was the connection must be short (ie 'less than 10 feet'). Wire too long, too many sharp bends, bundled with other wires, inside metallic conduit, splices, etc cannot perform the necessary earthing.

The key word is impedance. Wall receptacle grounds are excessive impedance. Effective protectors are located at the service entrance and as close to single point earth ground as possible. Why? Again, a protector is only as effective as its earth ground. That also means a connection as short as possible. Effective 9and properly earthed) protectors do not fail even when earthing a direct lightning strike. As was routine even 100 years ago. Routine in most every telco switching center, munitions dumps, cell phone towers, commerical broacasting stations, and homes where simple protection is properly installed.

Separation between a protector and electronics further increases protection. Why? For the same reason why wall receptacle ground is an insufficient connection to earth - higher impedance. Protection is always about where energy dissipates. Either harmlessly in earth. Or destructively inside a building.

Ok, but I was still disappointed the other day when we had a power surge, and the Mac shut down. We have a "whole house" protector, and a cheap power strip "surge protector" that the Mac is plugged into. It didn't matter.

toMACsh said:

Ok, but I was still disappointed the other day when we had a power surge, and the Mac shut down. We have a "whole house" protector, and a cheap power strip "surge protector" that the Mac is plugged into. It didn't matter.

Click to expand...

If you had a power surge (high voltage), then you could list destroyed hardware. If you had a blackout (low voltage) then hardware experience normal and ideal conditions; only data was lost.

This posted because I am amazed how many are now told by retail salesmen that a blackout is a surge. Amazed how many believe that salesmen.

Now, if you had damage, well, read what was posted. No protector ('whole house' or plug-in) is protection. Only earth ground is protection. The only items always required in every protection 'system' is earth ground. If you had damage, then you still have a defective earth ground.

Why are 'whole house' protectors so effective? The effective solution makes that short (ie 'less than 10 foot') connection to protection - earth. The plug-in protector does not even claim protection in its numeric specs. Obviously. Where is its 'less than 10 foot' connection to earth? Does not exist.

How do you know a surge existed? Surges are not blackouts.

If a 'whole house' protector is properly earthed, then nobody knows a surge existed. A direct lightning strike would not damage a properly earthed protector. Nobody would even know that direct lightning strike surge existed - if a protector is installed as it was installed 100 years ago.

Blackouts (low voltage) are not surges (high voltage).

Ok, we were "momentarily" without power; a blackout. It was enough to make the alarm clocks flash 12:00 and that's all; no damage.

You seem to be saying that there are ineffective whole house surge protectors, and effective ones. I wouldn't know how to determine if ours has a connection to ground less than ten feet from ________. (the circuit breaker box?)

toMACsh said:

You seem to be saying that there are ineffective whole house surge protectors, and effective ones. I wouldn't know how to determine if ours has a connection to ground less than ten feet from ________. (the circuit breaker box?)

Click to expand...

From every breaker box is a quarter inch solid (and bare) copper wire. Where does it go? Well, one must go to water pipes. A fault (electrifying a water pipe) means that electricity is removed from the pipes because the ground wire is connected. Otherwise one can be electrocuted in the shower or bath.

Another wire must go outside to an earth ground rod (or other electrode). It must exist to meet 1990 National Electrical code. And it does not exist on numerous homes. A 'whole house' protector is as ineffective as a plug-in protector if that ground wire does not exist.

Again, where does energy get harmlessly dissipated? If that wire does not exist, then energy is inside your building hunting for earth destructively via appliances. No earth ground means no effective protection. Only inspection can determine if that ground wire and earthing electrode (ie ground rod) exists.

That wire exists to meet safety codes. Surge protection means that earth must exceed code. For example, if that bare copper wire goes up over the foundation and down to earth, then you have compromised protection. That wire is too long. Too many sharp bends. Bundled with other wires. That ground wire must go through the foundation and down to earth to be shorter, less bends, and separated from other wires. That connection must be as short as practical.

Inspection is trivial. Locate the bare copper wire both inside (near the breaker box) and outside (where is connects to an earth ground rod(s). If you don't have it, then you still have no surge protection.

Many are missing this earthing. Either disconnected or it never existed. Some are even missing that other bare copper wire to water pipes. The lights still work; therefore everything must be OK? Reasoning that can even cause death. Only inspection can confirm both ground wires exist.

Surge protector is not a magic box. Too many (including some electricians) want to view the magic box (a surge protector) as protection. Protection is that bare copper wire and the earth electrode it connects to. Only inspection can confirm it exists.

I usually see maybe as much as two out of ten older homes do not even have that water pipe connection. Unsafe and cannot provide surge protection. Only a homeowner is responsible for maintaining those grounds. Nobody will fix that defect when the homeowner does not first learn this basic knowledge.


You have described a blackout. With so many naive 'experts', many are told that blackouts are surges. A problem made even more apparent by increasing numbers of computer repairmen who do not know how electricity works. A+ Certified computer techs need not know anything about electricity to pass that test. Which is why so many electrical myths (ie a blackout is a surge) get promoted.

Westom, I warn people all the time about that very thing and most will not listen. Thanks for posting this info. It might save someone's house, equipment and even their lives.

I'm saying that the strike happened in such way. There is a collection of windows in my home, and there is a stereo system right near this area of the living room. The lightning struck one of these windows directly, as the metal frame seemed to serve as a conductor which eventually blew out a piece of the wooden window frame itself. The 'voltage' seemed to pass through this area and onto the ground where my stereo wires and computer cords were located. The systems were seemingly fried, my house alarm started going off and that was the incident in a nut shell.

Now, the iMac starts up with no RAM installed, and the screen goes from compltetely black to dimly lit blue/black screen. The machine itself doesnt sustain the same sound as usual, I don't know what the problem is but you can tell that there certainly is something.

Do you guys have any suggestions pertaining to a repair for this computer? I'd appreciate it in advance