Home Forums Hardware Mac Desktops & Notebooks EMI Shield

My daughter who's away at university had problems with her G5 iMac. It sounded to me like a power supply problem so she took it into a local shop who confirmed. They also said that they couldn't get a replacement part so I ordered one from iFixit.

She brought the machine home for Christmas and we successfully completed the repair. However, the repair shop didn't just fold back the EMI shield that runs across the bottom of the machine. They cut it out entirely.

Question: Do we need to be concerned? Is it going to be a problem when she uses other devices like her microwave?

It would be more likely the lack of an EMI shield would cause her iMac to create interference for over the air TV signals, AM or FM radios, cordless phones, etc. than the other way around. Back in the 70s and 80s that was a real problem for those with home computers and the level of RF signal radiation was a major marketing point. But as the hardware designers got smarter and the general level of shielding became far greater, due in no small part to federal regulations, concern about RF emissions shrank to insignificance.

Whether it bothers your daughter or not her roommates, and neighbors, may well suffer from electronic noise on their audio or video devices.

Okay thanks. Next question, how do we replace the EMI shield and if we can't get a replacement to put inside the machine, should she just tape something like silver foil across the back of the machine on the outside?

Clearly we'll wait to see if there are problems......just want to be prepared, in case.

Also, I've suggested she go back to the shop and question why they didn't return her machine to her in the same condition as received.

I don't know what the shield in her G5 iMac looks like, whether it is perforated or not and its physical layout, but proper, controlled, cooling air circulation has always been critical in G5s. (Remember the liquid cooled G5 towers?) For that reason, I would be reluctant to either leave the shield out or replace it with some sort of a patch. Hopefully Virtual1 will chime in here with some sage advice from his personal experience or a source where you can obtain the correct part.

Thanks for some interesting thoughts. They're appreciated.


If so, it's an iSight iMac Power PC G5, 1.9GHz, 17 inch.

> Also, I've suggested she go back to the shop and question why they didn't return her machine to her in the same condition as received.

"Question?"

You're quite the diplomat.

Yeah....certainly more so than my daughter. She had somewhat stronger terminology and I'm quite sure the shop will not have a good time of it.

that EMI shield is well known to be a pain for service. It's made of a lamination of a black insulating plastic and an EMI-insulating foil. In older models, the adhesive that glues the foil side to the machine frame hardens and becomes much stronger than the adhesive between the layers, which also weakens with age and can fail completely. When trying to peel back the shield, it's very common for the layers to separate, leaving the foil glued down on the metal frame. This also can lead to the plastic tearing, because the foil is what provides the sheer strength.

The result is the shield can get ripped to shreds when trying to remove the LCD panel for service. Preventing damage is difficult, time-consuming, and often is in vane. The foil is also on the side and across the top and will get torn up just the same there. We frequently end up cutting the sides away because it's impossible to peel it loose. Sometimes we manage to pry it loose but the adhesive is shot or the foil is still separating from the plastic, and is impossible to stick back down again anyway.

That shield is there more to make the UL and FCC etc happy than anything else. You're very unlikely to experience any side-effects from its removal. They probably just cut it off to save time or it got torn up and they removed it to be neat.

Don't blame them, this is a materials flaw in the product, blame Apple.

Thanks. I'll let my daughter know.