Troubleshooting Modems | Tech Info Home Page | Troubleshooting | Modem Info |
General Info, External Modems, Internal Modems, Both, Test the Modem, Check for Conflicts, In General, Links
For general information about modems see the "Modem-Information" page.
To see current modems, drivers or tech support Links go to the Modems page.
This page applies to problems with computers running windows 95 and is assumed that your modem is physically connected to the computer. Windows 98 troubleshooting is almost identical.
Modem problems can the the hardest to track down especially for internal modems.
There are 3 connections that must be made. The power must be connected between the modem and the wall outlet and the data cable between the modem and the computer and the phone plug must be properly connected to the phone system and the computer.
Check all 3 below to make sure you they are all properly connected.
The data cable
Normally a cable with a DB-25 male plug on one end and a DB-25 female plug on the other end is used. The external modem has a DB-25 female plug and the back of the computer has a DB-25 male plug. Some com ports are only 9 pins, and if your cable has a 25 pin plug you can buy an adapter that has a 25-pin on one end and a 9 pin plug on the other.
The power cable
Additionally, a power supply is used. Plug the round end of the power supply to the back of the modem in the provided jack and plug the other end to the power outlet. Usually when the modem is properly connected to the wall outlet at least one of the modem lights will come on.
The Phone line
A thin cable with a small (RJ-11) connector at both ends is used. One end of course goes to the wall telephone jack. The other end goes into the back of the modem. On some computers it is very critical to use the proper plug on the back of the modem. Check with your modem user's guide to see which of the plugs is used for the computer and which is used for the wall jack. There are two female plugs on the back of the modem and for those modems where it matters what plug you use, if you plug in the wall outlet on the wrong plug the modem will not work.
When all connections have been checked, follow the instructions for testing the modem.
For computers running Windows 3.x with a Plug-N-Play BIOS, you need to install a special driver which is normally provided to you on a diskette by the manufacturer of the modem.
The Phone line
Always check to make sure there is a good connection from the back of the computer to the telephone wall outlet. On some modems it is critical to use the proper plug on the back of the modem. Check your user's manual for instructions on which of the two plugs to use for the telephone jack (wall outlet) connection.
Before starting it is a good idea to check the current hardware IRQ settings that your computer is using.
If the modem is not Plug and Play (PnP) then check the jumper settings and record the com port and IRQ number so you can compare it to what other devices are using. No two devices can have the same settings.
If the modem in PnP then Windows 95 will automatically assign the settings for you.
Check Current Settings in Windows 95
Open the control panel, double click on System, and click the Device Manager tab. The system properties window will open. You should see at the very top the word "Computer" highlighted in blue, if not, click on the word "Computer" with your mouse.
Next click on the button "Properties". The "Computer properties" window will open showing a white text box with 2 columns, the "Setting" and the "Hardware using the settings" columns. The "Setting" column will show all the IRQ lines used in the form of "00", "01" ...all the way up to "15". Record these numbers and the associated descriptions next to them.
Internal modems have to be configured to use an IRQ line. The standard IRQ lines for communication ports are:
- Com1 - IRQ4 , address 3F8h to 3FFh
- Com2 - IRQ3 , address 2F8h to 2FFh
- Com3 - IRQ4 , address 3E8h to 3FFh
- Com4 - IRQ3 , address 2E8h to 2FFh
Since most computers some with 2 built-in serial ports, many computers that have an internal modem installed have some kind of problem due to com port conflicts.
If a serial mouse is used
If your computer uses a serial mouse, you must make sure that the modem is NOT configured to use the same IRQ line as the mouse. There are very few options here.
First you can try disabling one of the com ports by either setting jumpers on the mother board or by entering the CMOS/BIOS and selecting Disabled for the entry referencing the modem.
Second you can try selecting a different IRQ for the internal modem. Also remember when changing IRQ lines to also change the corresponding Address as shown in the table above.
For PnP modems it can get even trickier. The motherboard will try to set the modem to a setting then windows 95 will attempt to set it again. In rare occasions, the settings get so confused that the only way to bring them back in sync is to go in the control panel/system/device manager and actually delete the com port entries and the modem and reboot the computer. After the reboot windows 95 will reinitialize all the com ports and the modem and hopefully straighten out the IRQ conflicts.
Both Internal and External
Make sure you have the modem driver loaded in the computer.
Test the modem.
Test the modem by opening the control panel, double-clicking the modems icon, and then clicking on the tab "Diagnostics". The "Modem properties" window will appear. You will see a white text box showing 2 columns, the "Port" and "Installed". A properly installed modem will be listed under the in this white text box. A picture of a yellow telephone will be shown in front of the Com port entry followed by the name of the modem to the right such as "Internal 56k FaxModem". Click on the picture of the yellow telephone. This will cause it to be highlighted by turning blue. Next click on the button "More Information". A message saying "Please wait...communicating with modem" will be displayed briefly while the modem is tested. In a few seconds the "More Information" window will be displayed having a white scrollable text box with column showing "Command" and "Response". Scroll the text box looking for any entries that have words like "error".
If errors are found then check for com port hardware conflicts (see below), and check to make sure the modem driver is the correct one and has been properly installed.
Check for Conflicts
Open the Control panel, then the system icon and press the device manager button. Look at the devices shown on the right half of the screen. Any devices that are not operating correctly will have a yellow exclamation point in front of the device.
Look for other causes to the problem.
Has the modem been working correctly and then started having problems?
1) If so, have you added any new hardware or software?
2) Does the computer give you any error conditions at boot up?
3) Does the modem drop the connection on a regular basis like every ten minutes? some times fax machines or telephones connected to the same line recharge their memory from the phone line and cause static. Try disconnecting those devices temporarily
4) Do you get dropped from the internet after using it for several hours? Try updating the Dial Up Networking (DUN) files from the Microsoft Site to the latest version.
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