crosson@cam.nist.gov (Bob Crosson) (10/31/89)
I have a friend who has a 3Com thinwire Ethernet. His 3Com server is at one end of the wire. A secretary's machine is near the middle of the wire. A third connection is beyond the secretary's machine when viewed from the server. All connections to the wire are through transceiver cables and single transceivers. The secretary's machine works fine. When my friend connects a Compaq 386 with a 3C503 Ethernet interface and 3Com software into the transceiver cable at the third location, everything works fine. When he plugs a Mac II with a 3Com Ethernet interface and software into the same transceiver cable, it doesn't work. It fails immediately when he tries to use the network. When he puts a BNC-T and two 50 ohm terminators on the transceiver in place of the thin wire, the Mac says everything is okay, but, of course, no connections can be made. The Mac interface is configured for a transceiver cable connection. Why do two 3Com interfaces, when plugged into the same transceiver cable and transceiver, operate differently? The only thing I can think of is that perhaps the power supplied to the transceiver from each of the interfaces is different, causing the transceiver to work differently. The transceiver and cable are from Cabletron and are probably Ethernet Version 2/IEEE 802.3 compatible. Can anyone suggest something to try? My friend is trying to contact 3Com right now. Thanks for your assistance. E-mail can be sent to Bob Crosson crosson@cam.nist.gov
tom@wcc.oz (Tom Evans) (11/10/89)
In article <1525@intercon.com>, amanda@intercon.com writes: > One thing I've noticed about a lot of Mac Ethernet adapters (from more > than one manufacturer) is that, oddly enough, the thick vs. thin jumper (or > switch) is labeled backwards. How do they select between Thick and Thin with only ONE jumper? I have seen it done on a very old box with lots of ECL glue (but that costs). Don't tell me they leave the unpowered Thinwire transceiver (and terminator resistors) across the AUI connector (shock! horror! :-)! --------- Tom Evans tom@wcc.oz.au | Webster Computer Corp P/L | "The concept of my 1270 Ferntree Gully Rd | existence is an Scoresby VIC 3179 Australia | approximation" Australia | 61-3-764-1100 FAX ...764-1179 | D. Conway
kr@apollo.HP.COM (Keith Alan Rodwell) (11/14/89)
Actually, the 3 COM 3c505 has only one jumper (actually, it is a block jumper, convering several sets of pins). So, it is possible to change from Thick to Thin by moving only one jumper. In article <448@wcc.oz>, tom@wcc.oz (Tom Evans) writes: > In article <1525@intercon.com>, amanda@intercon.com writes: > > > One thing I've noticed about a lot of Mac Ethernet adapters (from more > > than one manufacturer) is that, oddly enough, the thick vs. thin jumper (or > > switch) is labeled backwards. > > How do they select between Thick and Thin with only ONE jumper? I have > seen it done on a very old box with lots of ECL glue (but that costs). > > Don't tell me they leave the unpowered Thinwire transceiver (and > terminator resistors) across the AUI connector (shock! horror! :-)! > ------------------------------------------------------------------------ ------------------- ``This theory which is mine, is mine'' -- Ann Elk (Monty Python) Keith Alan Rodwell Apollo/HP Customer Support (508)-256-6600 X8415