I am attempting to configure an IBM 8275-416 switch (I found a manual here) via serial connection. However, when I connect with HyperTerminal, the output contains a lot of garbage characters. It's pretty much unusable, because there's enough layout-breaking text-gunk that it's very difficult to determine what's actually being displayed.

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I was able to reset the switch to factory defaults via the terminal interface, so I know that it's not entirely broken. It also performs basic functions all right (i.e., you plug in clients and Ethernet cables -> they can connect to clients plugged into other ports) - but I'd like it to do more than that (VLANs yay). I don't know if its in-band UI is operational or not, because I can't get the terminal interface to behave well enough to properly turn on the web/SNMP UI. So that's not available.

Things I've tried:
- Changing the encoding: HyperTerminal lets me choose between Standard JIS and Shift-JIS. Neither setting fixes the issue.
- Checking emulation settings: The manual demands VT100, 19200 baud, 8 data bits, and such: I have faithfully applied these settings, both in HyperTerminal's settings and in the properties of the COM1 port in Device Manager (connecting from a Windows machine).
- Restoring to factory defaults: See above.

Things that it could be, but that seem unlikely:
- Cabling: Couldn't find a proper null-modem cable, so used two 232-to-RJ45 adapters. But if it was a problem with the cable, wouldn't it be more likely to not connect or do input at all, rather than just garble the text? Since I was actually able to perform the reset-to-factory defaults operation, I don't think it's this.
- Device as a whole broken: It is a decade and change old, so it's possible that it's just dying slowly. Again, though, it seems like there would be more symptoms than just garbled text in the terminal.

What else can I try to get a sane interface to this switch?