Replacing a Modem

Illustrated How to replace a modem (Internal 56K)

All of the other replacement illustrations on this site are shown with computers built in mid-tower cases, so just for variety, I've illustrated installing a 56K modem in an old style desktop case. The only difference is how the cover comes off and how the case sits, the ATX motherboard and modem are identical to those used in tower cases. As with pretty much all generic case designs, you remove the cover by removing the screws on the back are through the painted surface of the case cover. Go through my flowchart for troubleshooting modem failure before replacing it.

Once the screws are removed from the desktop case (three in this instance, some use five), the whole cover lifts and slides out. If what remains looks familiar, it's the standard mini or mid-tower cases are essentially desktop cases stood on end. You can see the ports on the modem we are installing between the video and sound card ports on the back of the case.

Standard PC adapters are secured with a single screw (unless the case employs a locking bar system), so the first step to install our modem is to remove the screw. Note the brown capacitor near the top of the card, the exposed circuitry on internal modems can give you a nasty little jolt if you handle them improperly, even though the power cord has been disconnected. Doesn't do much good to know how to install a modem if you can't get the old one out without zapping yourself:-)

Our new 56K modem has the capacitors mounted vertically rather than horizontally, so you can see I'm not cheating and just putting the same modem back in:-) The most common reason for modem failure is lightning strikes, and modem often fails open. This means if you come home one day and your telephone is dead (no dial-tone), and all the phones in the house are hung-up, the next step is to disconnect the computer modem. If the phones in the house are fine after the line connection is disconnected, it's time to replace the modem.

When you install the modem, be careful not to touch the contact edge (the gold stripes) when handling the adapter, and hold it by the metal bracket the back corner of the card. Seat the modem in the PCI slot with even pressure on the top of the card. Once it settles into the slot, secure it with the screw, but don't tighten it until you confirm that the ports fully exposed through the back of the case (below). Also, make sure the "line" port on the modem is connected to a live phone jack in the house. The "phone" port on the modem is for attaching a regular telephone.

People who live places with inexpensive broadband connection don't realize that modems even exist anymore, but you and I know better. Modems were always one of the highest failure rate PC components, with lightning strikes being one of the main culprits. But there are plenty of issues that can prevent you from connecting to the internet or which can slow your speed to a crawl which aren't due to to the modem going bad. I included two flowcharts for modem troubleshooting in Computer Repair with Diagnostic Flowcharts, one for failure and the other for performance issues. The 120 page printable eBook version with 17 flowcharts and text can be instantly downloaded anywhere in the world for $9.95. Even at today's low modem prices, the book is cheaper if you figure in shipping for the modem which you may not need.

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