On Thu, 8 Apr 2010 06:46:02 -0400, "Armond Perretta"
wrote:

Bruce wrote:

As far as the instrument problem is concerned the logical plan would
be to undo the last thing done, i.e., disconnect the Tach and see what
happens?

Hardly rocket science but if only one thing changes - the bloke
connects a different tachometer - and all the instruments fail then

Which I will of course try today. Yesterday I tried switching the old tach
wires (see original post). That was a "no go" because the connectors allow
only one proper connection on the new instrument. Note that only the temp
gauge is acting up. All other gauges (oil, voltage, tach, alarms, lights,
etc.) perform properly.

Still, I'd reverse my "repair" and see what happens. A heat gage going
full scale indicates that somewhere between the instrument the temp.
sender you have a short to ground and/or the sender in shorted to
ground.

You can isolate things a bit more by disconnecting the existing
connections to the Temp. Gage and connecting a jumper from some known
source of power to the proper terminal on the gage, then temporarily
connect the wire from the temp sender, to the gage and see how it
works.Try using a jumper of some sort, make a whole new connection
from the gage to the sender and see what happens. This should give you
a pretty good indication of what is working and what is not. If you
find that isolated from everything else on the panel the Temp Gage
works then you can investigate the "everything else".

And yes, this is exactly, leaving out experience, how a professional
instrumentation guy will do it - isolate the instrument and it's
sender from everything else to determine whether it is the instruments
themselves or "everything else", fix either the instrument or
"everything else".


Cheers,

Bruce
(bruceinbangkokatgmaildotcom)