Network Adapters

Posted by: repair  :  Category: Video, Sound, Modems, and Network Adapters

Network Adapters (Network Cards, Network Boards, Network Interface Cards, NICs, Ethernet Adapters)

Considering how complicated networking can be, network adapters are rather simple. They are among the easiest devices to install; simply follow the manufacturer’s directions. Cards made by 3Com and Intel are often installed automatically by Windows. Others, including external USB models, require driver disks, but are still easy to get up and running.

Selecting a Network Adapter

Older network adapters came in myriad types, but today’s cards are mostly Ethernet cards. Ethernet is a network standard that almost exclusively uses Cat 5/Cat 5e UTP (unshielded twisted pair) cables with RJ-45 connectors. RJ-45 connectors are very similar to standard RJ14 modular telephone plugs, but are twice as wide and have eight wires. Many of today’s motherboards come with built-in Ethernet adapters. Ethernet transmission speeds have increased from 10 to 100 to 1000 Mbps. Older cards worked at a fixed speed, preventing their connection with any network device running at a different speed. Newer cards, however, can automatically switch to a lower-than-maximum speed to match the device they are directly connected to, be it a router, switch, hub, or other Ethernet adapter. The vast majority of Ethernet network adapters on the market will work fine for most users with home or small business networks, or high-speed Internet service that requires network adapters.

Wireless Network Adapters

Wireless models come in various types to work in desktops or laptops. They require wireless routers to work. They work similarly to cordless telephones; they have to stay within a certain distance of the base (router) to maintain a connection.

Diagnosing Network Adapter Problems

Many things can go wrong with networks, but not many problems can occur with the adapters; usually, they either work or they don’t. Check in Device Manager to see if there is a problem. If reinstalling the driver doesn’t fix the problem, it is probably time to replace the card.
If Device Manager indicates a working adapter, it is a good idea to check the cable. Use a tester, or swap it with a known good cable.

Note Make sure to use the right cable for the job. RJ45 telephone cable, if it is not Cat5 or Cat5e, will not be reliable for network transmission. There is also such a thing as a crossover cable, which is used only for a direct connection between two computers with Ethernet adapters, or between two central devices such as hubs, switches, or routers. A crossover cable won’t work for a connection between a central device and a computer, and a straight-through cable won’t work with a two-computer network or between two central devices. Crossover cables should be marked on the cablesinsulation. If there is any doubt, you can check it with a cable tester. Please note that general networking is beyond the scope of this book.

By : Book-PC Repair and Maintenance: A Practical Guide

Modem Cables

Posted by: repair  :  Category: Video, Sound, Modems, and Network Adapters

Different external serial modems use an assortment of different types of cables. Make sure the cable is actually a modem cable; other cables might fit, but that doesn’t mean they’ll work. Also try testing the cable in a cable tester. With USB cables, it is often easy to swap with a known good cable.

For information on troubleshooting network connections, seeTroubleshooting Internet Connections.”

Cable and DSL Modems

Cable and DSL modems are external devices used to connect computers to a broadband (high-speed) Internet connection. DSL models connect to the telephone line without a DSL filter. A DSL filter is a device that blocks the DSL signal from interfering with regular telephone conversations; these are usually provided by the DSL provider. DSL modems are connected to the computer either through a USB cable or an Ethernet network cable. Cable modems are similar to DSL modems, but they connect to a television cable instead of a telephone line.

Modem/Sound Card Combinations

No longer manufactured, modem/sound card combinations are very difficult to get drivers for. The best way to deal with failed modem/sound card combos is to replace it with individual components. If you have only one free slot, you can probably replace the modem with an external modem.

By : Book-PC Repair and Maintenance: A Practical Guide

Diagnosing Modem Problems

Posted by: repair  :  Category: Video, Sound, Modems, and Network Adapters

Modems can be troublesome. If you have a telephone communications problem, there are a number of things you can do to check to see if the modem is working.

Note It bears repeating that the message often seen in the properties of any hardware device, “This device is working properly,” is often wrong. However, if you seeThis device is not present, not working properly, or does not have all the drivers installed. See your hardware documentation,” you can bet that it is right.

Here is a list of places in Windows where you can check to see whether a modem is working:

  1. Modem Properties in Device Manager, General page: If you see a message that indicates a problem, the modem might need to be reinstalled or replaced. Follow the directions or from the modem manufacturer to reinstall the driver.
  2. Query Modem: Go to Modem Properties from either Control Panel or Device Manager and click the Diagnostics tab if one is present. Then, click the Query Modem button and wait for the report. If the last couple entries in the report indicate OK, the query hasn’t detected a problem. You will often see the lineCOMMAND NOT SUPPORTEDat one point in the report. You can ignore this.
  3. HyperTerminal: Go to Start > Programs (or All Programs) > Accessories > Communications > HyperTerminal, if it is installed. You will be prompted to set up a connection. Give it a simple name; you won’t be saving it. Figure 8.9 shows this page.

    Figure 8.9: Naming a HyperTerminal connection.

Then, enter a single-digit telephone number. Make sure your modem is listed in the Connect using box. Click OK and you will be prompted to dial the number you entered. Click Cancel. You will see a blank HyperTerminal window. TypeATand then press . A working modem should respond withOK,” as shown in Figure 8.10. Then, you can close HyperTerminal and elect not to save the connection.

Click To expand
Figure 8.10: Autodetecting the modem in HyperTerminal.
Note Some malfunctioning modems can nonetheless pass every one of these diagnostic tests.

It is also a good idea to test a suspect modem with every function in which it can be used on the computer. This is to rule out the possibility that a program, rather than the modem, is malfunctioning. For example, if a modem works with faxing and Phone Dialer (Start > Programs (or All Programs) > Accessories > Communications > Phone Dialer), but not on the Internet, it is likely that the problem is in the Internet software or service rather than with the hardware.

Note You might find that Phone Dialer doesn’t work properly in Windows 2000 on certain machines no matter what you do. However, Windows 9x’s Phone Dialer (dialer.exe) might work in the newer Windows versions. If the modem will dial a number in Phone Dialer but do nothing else, the problem might very well be the hardware; we had a batch of new PCI modems that did this. The modems weren’t recognized by the Plug & Play system and had to be installed manually because they were defective.

It is unfortunately common to get certain numbered error messages such as 619 or 693 when trying to connect using a modem. You might try several times in a row and get several different error messages. Often, these error messages bear no relationship to the truth. When you get one of these, first attempt to rule out the problem that the message indicates, assuming you can understand the message. The problem could be as simple as a bad telephone cord, the Caps Lock being on and altering the password, or that the telephone line is in use. Other possibilities include problems with the remote computer or service, or incorrect password or username. If the computer locks up every time you try to connect, you probably have a resource conflict. See Chapter 2 for information on resolving it.

Note Make sure that the user doesn’t plug a modem into a PBX telephone line. Even though PBX systems can use RJ-11/14 telephone connectors, the voltage and signal are different. This can damage the modem, but it might merely cause the computer to lock up.

Once you have ruled these out, the next step is to reboot the computer, especially if you have a laptop. With some laptops, a design flaw causes certain functions not to work after the computer comes out of standby or hibernation. Rebooting might solve other problems as well. If none of these steps works, delete the connection and recreate it. If you still have the problem, it is time to try new hardware. Swap the modem for a known good unit and retry the connection. This is the perfect time to try an external modem if you have one. If you still can’t connect, and the modem is removable, try it in another system.

If a built-in modem on a laptop fails and you have reinstalled the driver to no avail, unless the laptop is under warranty, your only recourses are to install a PC-Card modem or use an external serial or USB modem. You might want to disable the built-in modem in the BIOS, if such a setting exists. Note, however, that sometimes seemingly permanent modem failures can occasionally resolve themselves over time.

By : Book-PC Repair and Maintenance: A Practical Guide