[Rhodes22-list] Network Quad problems

[Graham Stewart]

I have always been surprised at the answers that are posted here to some of
the most difficult questions so I am posting this question as a last
desperate attempt to get help.
I have been using my B&G Network Quad (speed knots, depth and water temp)
instrument for probably more than 20 years and it has worked without fail.
This year when I launched the boat it worked perfectly for the first day but
thereafter the speed reads 0.00 continuously and the depth and temperature
show erratic numbers.
I checked the paddlewheel for obstructions and it was fine. Spinning the
wheel manually makes no difference to the display. The fact that the display
comes on tells me that power is not a problem. It seems unlikely that both
the speed and the depth transducers would fail at the same time. The wiring
hasn't changed. The common element in the wiring is the connection to the
"sea ground" which  I don't have but has never been a problem. Nevertheless
I connected the ground to a brass thru hull and that made no difference.
I can't help feel that some tweak would fix the unit but I am now at the
point where I am completely stuck with no idea what to try. So, if anyone on
da list has a clue what I might do to diagnose the problem I would be most
grateful.

Graham Stewart
Agile, Rodes 22, 1976
Kingston Ontario