H
Holophote
- Jan 1, 1970
- 0
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?
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?
