[Rhodes22-list] Network Quad problems

[Graham Stewart]

Well I finally got a chance to do some electrical investigating using
Roger's  much appreciated strategy but have come up short. The battery,
which is new and fully charged reads 12.63 volts on its own without the main
switch engaged. I get virtually the same reading with the system switched on
and the same again for the leads where they enter the display unit. I
checked the line out from the display and it is the same. So I seem to have
full power going to the display. 

The fact that all of the readings are either missing entirely or steadily
rising makes me think it might be a faulty unit. If anyone can think of
anything else I might check I would appreciate the suggestion. I really
don't want to have to buy or install a new unit.

Thanks to all for their suggestions.

Graham Stewart
Agile, Rodes 22, 1976
Kingston Ontario
-----Original Message-----
From: Rhodes22-list [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of
ROGER PIHLAJA
Sent: Tuesday, July 7, 2020 9:15 AM
To: The Rhodes 22 Email List
Subject: Re: [Rhodes22-list] Network Quad problems

Hi Graham,

Just because the display comes on does not necessarily mean you have no
power issues.  The LCD display will operate on low voltage and requires very
little current.  The fact that your unit operated for 20+ years without a
"sea ground" means it was operating with ground defined as the battery's (-)
terminal.  So, here are some things to check:


  1.  Check the voltage at the battery terminals.  If the battery is 100%
charged and all circuits are turned off, the voltage should be ~13 VDC.  If
the voltage is <=12.5 VDC; then disconnect the (+) & (-) terminals and
measure again.  If the voltage is still low, try charging the battery.  If
the battery won't accept a charge; then, it needs to be replaced.
  2.  If the battery voltage is ~13 VDC, turn on the instrument circuit.
Again, check the voltage at the battery.  If the voltage drops; then you
have a short circuit in the instrument wiring, the instrument itself, or a
bad battery.
  3.  Now, check the voltage at the instrument.  It should be nearly the
same as at the battery.  You can check your B&G Owner's manual for the
minimum power supply voltage.  On my Raymarine Autohelm ST50 instruments,
the specified voltage range is 11.0 VDC <= [Supply Voltage] < 16.0 VDC.  I
have found the ST50 instruments will keep operating long after all the other
electronics have shut down due to low battery voltage.  But, your B&G system
might be more finicky about proper power.
  4.  If the voltage at the instrument is too low; then, try disconnecting
the power from the instrument and then measure the voltage on the wires.  It
should be the same as at the battery.  If you have proper voltage in the
disconnected wires and low voltage when you connect them; then, you have
isolated the problem to the B&G instrument itself.  Good luck getting
service on a 20+ year old instrument!

If I were a gambling man, I would place my bet on a bad battery.

Roger Pihlaja
S/V Dynamic Equilibrium

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10

From: Graham Stewart<mailto:gstewart8 at cogeco.ca>
Sent: Monday, July 6, 2020 8:49 PM
To: 'The Rhodes 22 Email List'<mailto:rhodes22-list at rhodes22.org>
Subject: [Rhodes22-list] Network Quad problems

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