The best way I see to test this is to plug headphones into your calculator. Make this program and run it with asm(.  This program makes a ~50Hz sound on both sides and has no way of quitting.

Code: [Select]

:AsmPrgm
:FBAFD30076EE031
8F9


real code (don't type this)
ei
xor a
loop:
out (00), a
halt
xor 3
jr loop

I tested it to work on mine and the sound will give you a headache, but it works.

For a volt meter, your best bet is to use Calcsys. I would assume you stuck a 2.5mm jack into the port and you aren't just sticking probes in there lol.

Go to calcsys, press 3, and you will be at port 00h which is the link port. With nothing else at this point, the calculator should be showing 5+ volts from both tip and ring to ground. Now press enter and type 03. This will set both of them to ground. They should be at 0+ volts or close to it. You can then test each connection by sending 01 for tip grounded and 02 for ring grounded.

I should also mention that when you send any of those values besides 00 the calculator, it will run very slowly if it even runs at all.

The times this has happened to me, it's been the relatively simple issue of TI's weak soldering job on the link port failing. The link port is a tiny plastic piece soldered onto the motherboard of the calculator at three points, each corresponding to one of the gold rings on the plug you put in the link port. If you can archive all of your programs to ROM, your best bet would be to do what I did with my very first TI-83, which eventually developed this problem. Open it up (you'll need a Torx-6 screwdriver and also a phillips for the backup battery) and locate the black plastic link port at the bottom of the motherboard. It's not even necessary to unscrew the motherboard for this fix: look closely at the link port and you should notice flaws in the solder on at least one of the pins. Once you find the pin or pins, heat a soldering iron, get some solder, then CAREFULLY melt the solder on the pin and dab a bit more on. Remove the iron after the solder to ensure a good connection. You might want to repeat one at a time for the other two just to be sure. Be very careful not to accidentally hit one of the tiny surface mount components around the port with the iron, as they come desoldered very easily and are nearly impossible to resolder with normal commercial tools. Then seal the whole thing back up and cross your fingers.

Can you run some tests while the calculator is opened?  See if you can get the voltage from touching the tips of the multimeter to the areas of solder.  It is possible that the jack itself is actually the broken part and might need to be replaced in which case you'd have to remove it and solder on a new one.