Expensive systems failure please HELP

[Janie Tyler 2]

Need advice lads from the technical dept. i was out on saturday with all systems working fine when i noticed my garmin 340 fishfinder had gone to a plain white screen with the message sonar timeout at the bottom.
shortly afterwards my standard horizon 180 chart plotter lost its brightness and appeared to go into night mode.( you could still see the screen, just very dark)
then my humminbird vhf radio started making sounds like a machine gun!
my mate totally rewired the lot as there was a lot of dubious wiring behind the console but all problems still exist.
can anyone enlighten me as to what may be going on?
surely they cant all decide to pack in on the same day?
i feel that some one occurrence has caused them all to malfunction, am i right and what could it be?
its a bloody expensive day out if i have to send them all away to be examined.
please help

[Nasher]

Only obvious thing I can think of is the regulator on the engine allowing over-voltage through to charge the battery, and hence suppling something too much over 12V to all the gear. Most gear should cope with up to about 14V, but any more than that could fry it.

Could be wrong though.

Nasher

[Janie Tyler 2]

Originally Posted by Nasher

Only obvious thing I can think of is the regulator on the engine allowing over-voltage through to charge the battery, and hence suppling something too much over 12V to all the gear. Most gear should cope with up to about 14V, but any more than that could fry it.

Could be wrong though.

Nasher

Thanks for the fast reply that's what I have been thinking but from a different source because this year I had two batteries installed with one of those auto change over switches fitted and was thinking that it might be doing it.

[chewy]

Can you remove the equipment and try it on a 12v power supply that you know is ok, a car battery or something?
It doesn't sound good though.

[Jizm]

What voltages have you got with the motor off and on?

[Bhives]

If two batteries and a suspicion of over voltage I would check to make sure they are not in series at any position of the auto-switch, this would give a 24 volt system.

[jwalker]

Garmin equipment is usually designed to function up to a system voltage of approx 35v. Check your Garmin user manual for your equipment.

[Erin]

Sounds very much like a poor connection on the power supply to the electronics. I'd double check every bit of wire and connection. It only takes a slightly loose or coroded bit to effect the current flow and dim things down.

[geoffs]

Sounds like not enough volts rather than too many, check for bad connections/corrosion.

[Janie Tyler 2]

Originally Posted by geoffs

Sounds like not enough volts rather than too many, check for bad connections/corrosion.

Yes Geoff that was the problem we eventually got to the bottom of it the second battery wasn't getting charged this was due to the auto change over switch being faulty so its now going back to the marine engineer who fitted it hes going to replace it under warranty.

Thanks lads for all your help in this matter and im glad its not going to cost a fortune replacing faulty electronics.