Originally Posted by Biggles
I have two Garmin transducers fitted.
Garmin 178 works perfectly all the time. Garmin 90 gives all sort of spurious readings. I guess the 90 is older technology but its very temperamental.
Both transducers are mounted to shoot thro the hull at the rear of the boat.
Thanks, but not sure what a 90 is. Is that pre-178/498?
One interesting thing is that the transducer of the 498 is much larger than the 178 one. It is both wider and longer.
I spoke to Garmin on this one, who suggested;
a) checking the transducer cable for damage (it seems OK, but impossible to check inside the cable to be sure! but if it works perfectly at times, surely cable must be OK?)
b) checking the transducer cable connector plug (just below main unit) - this seems OK too
c) they think electrical interference unlikely as 1) their cable is shielded and 2) nothing else electrical was on at the time (apart from the engine! and even when I turned that off the problem was still there).
d) check the software number as suggested above - but to upgrade I need a lead I think
e) check the transducer itself by using another loose transducer - impossible, I don't have one!
f) have the main unit checked for faults.
So plenty of things to look at - I hope it's simple as this is brand new, and I would rather it wasn't a major breakdown, especially after the 178 worked so well.