RARE LINE NOISE PROBLEM CAUSES On-Line Version Last Revised: March 25, 1993 Supra Corporation - World Headquarters 7101 Supra Drive SW, Albany, OR 97321 General: (503) 967-2400 Fax: (503) 967-2401 Sales: 7:00am - 5:00pm PST, M-F (503) 967-2410 (800) 727-8772 Supra Tech Support: 8:00am - 4:30pm PST, M-F (503) 967-2440 GENERAL (503) 967-2490 IBM DOS & Other Products (503) 967-2491 IBM WINDOWs (503) 967-2492 MAC (503) 967-2493 AMIGA Supra BBS........(503) 967-2444 8 lines 24 Hours v.32bis v.42bis LAPM 2-5 CompuServe.......76004,565 BIX..............SupraCorp America Online...SupraCorp2 GEnie............SupraTech AppleLink........D2456 UseNet EMail.....supratech@supra.com ------------------------- (Article Begins Here) ------------------------- If you have an older SupraFAXModem with pre-version 1.2H ROM chips, you need to get a ROM upgrade from Supra instead of using this checklist. To find out what version ROM chips your modem has, type AT I3 from your telecom software's terminal mode. Once you've verified that your ROM chips are version 1.2H or greater, here are several uncommon line noise problems you may want to consider. Building Wiring: Wiring in older buildings can cause line noise problems. There are two such wiring problems: 1. Lack of "twisted-pair" wiring. Non-twisted pair wiring consists of four wires: green, red, yellow, and black. Twisted pair wiring consists of a matched pair of wires: one wire that is colored with a white stripe, and one that is white with a colored stripe (i.e. white with blue stripe and blue with white stripe). To solve this problem, you need to replace the present wiring with twisted pair wiring. Your local telephone company may be able to help you with this. 2. Routing next to AC power wires. To solve this problem, the phone wire must be re-routed, away from the AC power wires. Distance from Telephone Company Central Office: Another problem is one that you can't easily do anything about. Simply put, the farther you are from the telephone company Central Office (CO) the more likely it is that line noise will be introduced into the lines by nearby AC power lines and other sources. This will most likely be a bigger problem for people in rural locations. Moving is about the only sure way to fix the problem. Magnetic Fields Interference: You could also experience line noise problems because you have your computer monitor or a stereo speaker on top of or very near your modem. These devices can interfere with the modem transformer, despite the modem's aluminum case. To solve the problem, move the modem away from these devices. -------------------------- (Article Ends Here) -------------------------- Copyright 1993 Supra Corporation Supra Corporation, and SupraModem are registered trademarks of Supra Corporation. SupraFAXModem, SupraSmartUART, SupraTurbo, and Silent Answer are trademarks of Supra Corporation.