Ok! Since I haven't gotten any helpful info from Yeoman or otherwise to
determine the pin out of the 4 pin data connector, I took things into my own
hands..

I opened up the plotter bed for access to the computer and the
interconnections..

Sure is a simple thing.. But that's another story..

To my immediate relief, there are 4 wires going from the circuit board to
the 4 pin connnector.. The colors don't exactly match those given for the 5
pin plug discribed on the web site. However Data IN is correct and there is
Green wire that 'may' correspond to the Data OUT. Signal Gnd should be the
same for both but there just happens to be two more wires of different
colors left over, one of which I'm using for Data IN signal gnd. I didn't
have any test equipment on board and most likely will do a trial and error
once I install a 4 conductor cable on the OEM plug.. (problem there-- it's
molded and not intended to be opened. I'll have to cut away the mold strain
relief and epoxy it back with the new wires.)

While I was in there poking around, I open the shield cover on the main
circuit board, to look for markings where the harness plugged in. None.. I
noted that the EPROM was marked with YM-22 Copy Right 1992. No other circuit
board ID but I wasn't able to inspect the solder side if the board..

I have ask BandGUS tech support about a full new circuit board with new
firmware to upgrade the unit.. Still waiting for a reply..

I know, that to some, this Yeoman may seem like "old tech" and not worth
messing with.. There does seem to be some 'die-hard' Yeoman devotees and as
I look at the simplicity of the whole scheme, I'm think seriously about
building the thin matrix mat into my chart table (as Larry has discribed). I
don't have the room for the whole plotting table to mount under the chart
table but I did check today and the mat and circuit board box assembly will
fit nicely.. The other cable are provided with connectors..

To justify my scheme, I can maintain my paper chart plot at all times and
put the laptop away once the more complex route planning has been completed
and the waypoints uploaded to the GPS.. The Yeoman only draws .5 amps and
can be used to solve near time nav problems and to update the plot.. If all
systems crash, the plot is still there on the Yeoman chart cover..

BTW.. I just tried pencil and ball point ink on the plastic cover.. The
pencil was hardly visiable and I suspect would eventually start smearing and
scratching.. With the ball point and only light pressure the ink transfered
to make a nice clean line. The plastic chart protector is made of a rather
hard plastic and there didn't seem to be any impression from the ball point.
To clean it off I just used a damp tissue.

I'll provide an update when I have more revelation or results.

Steve
s/v Good Intentions