My elderly father doesn't spend a lot of time surfing the internet, but I thought he might benefit if I replaced his old V.90 modem with a true hardware- controller based modem. As far as I can tell, only US Robotics and MultiTech make an internal PCI V.92 modem with a flashable BIOS.
I purchased the MultiModem ZPX made by Multitech. As soon as I removed it from the shipping carton I knew there was a problem. My dad has significant hearing loss. He uses a pair of amplified speakers plugged into a jack on his old modem, so he can hear the dialtone and modem handshaking.
I have an extensive electronics background, so I thought if the MultiTech modem worked ok I could add an external jack.
Here's what I did:
I removed that micro sized piezio speaker element that is part of every modem. If you put your head near the modem card you can hear something from this useless part. I was fortunate because the speaker element had a big "+" on one of its two pins. I soldered socket pins in each hole. These pins are often sold in a breakable strip. You snap off as many as you need.
I used very narrow gauge coax audio cable. I soldered about 1/4 inch of 24 gauge bus wire to the braid and center conductor of the audio cable. The 24 gauge wire fits perfectly into the socket pins. (Yes, I did use a heat sink to prevent the center conductor insulation from melting. I checked the coax for shorts. Its ok.)
I installed a monaural jack through one of the retaining brackets in an empty expansion slot. I selected a good pair of small amplified speakers. The power is not provided by a wall-wart, but they do have an enclosed style transformer inside one of the speakers which provides isolation from the mains. Since all speakers are configured for stereo, I used a stereo-to-monaural adapter plug.
I knew things might go wrong, so I used a small breadboard to test the circuit. The coax braid was connected to the ground pin on the jack, and the center conductor was plugged into a 1 uf coupling capacitor which in turn was clipped to the jack pin in contact with the plug tip.
As soon as I started the computer I could hear a low volume oscillating noise through the speakers. When the modem is prompted to connect to the web I hear nothing but that oscillating noise.
Just to see what would happpen I pulled the coax ground. When I prompted the modem again to dial and connect I could hear the dialtone and handshaking through the speakers but it was barely audible, even with the volume control turned all the way up. I did try several different capacitors, but it didn't make any difference.
Have I entered an electronic black hole, or is there a solution that I'm overlooking?