Nav computer problems

Went to the boat toady and fired up the nav computer and other devices. The GPS is working fine, sending out the NMEA sentence. The VHF, Radar and SSB all see it fine, UNTIL the nav computer is turned on. About halfway through the boot up (Win XP) all the other receivers lose the NMEA sentence. Checked all the obvious settings; nothing has changed since the last time I fired it all up. Everything works fine until I turn the computer on. The GPS send cable is hooked up to a terminal strip, where the other instruments get the string. This has worked fine for 7 years. ??? I'm thinking the serial port/card has gone bad? I tried all the various troubleshooting methods... changed the baud rate, changed the NMEA from 183 v2 to v 1.5, 1.0, etc. Used Nobeltec's setup and it didn't see any NMEA strings on com 1 (where it should be receiving) or com 2. This is a Big Bay bookshelf marinized computer. Since it's a "strange" size, I doubt I can just run down and get a new serial card. Nothing in device manager shows a problem.

Any ideas?

Keith,

Try disconnecting the PC connection to the "system" before booting up, while leaving all other connections as normal. Once PC is up and running (but you won't have a GPS indication on the Nobeltec), and all the other goodies are still operating, plug the connection into the PC and see what happens. If the "system" dies when you do this, it's probably the serial card.

Also, you can buy/fabricate what's called a "loopback" cable. The connects the Xmt & Rcv together on the back of the PC. You can then run Hyperterminal, create a "new" terminal connection, and whatever you type on the screen should echo back at you. Again, if it doesn't, it's probably the serial card. If it does echo, check the cable from the PC to the terminal block.

Hope this helps.

Yea, it dies when I plug the serial cable back in. Too late for this trip... I'm using my laptop with the backup copy of Nobeltec on it. I'll finish troubleshooting the other computer after we return, probably with a paperclip stuck in the transmit/receive pins. I'm pretty sure the card has gone bad, but with it being a "bookshelf" computer, it'll be a little harder to find a half height or whatever the call it... card.