Intermittant problem with Icom M802

[NahanniV]

Originally Posted by ka4wja

....
But, something you wrote earlier slipped past me....you wrote: "turning off the breaker will not restore it"....
And, I'm now thinking: "what breaker?"...
Standard practice calls for the radio to be powered directly from the hosue battery bank (or buss bar), and NOT thru a breaker panel / distribution panel, as these typically allow way to much voltage drop (as well as present significant opportunities for RFI)....
So, if you have the rig powered thru a breaker panel / distribution panel, you may have an intermittent connection issue there, that once it cools off, is good to go....but once it heats up is causing a low-voltage cut-out???
So, please wire the rig to the batteries or buss bar, using a larger gauge wire than what is supplied with the M-802, and test again....you may find the trouble in short order!!

....

Thanks,

I took the rig over to the Winlink operators shop today.
After trying to reproduce the problem for over half an hour with the transceiver connected to a dummy load we were just about ready to give up and start to look at the tuner, but one last try put it into the locked up state. That was very lucky, or I would still be searching for the problem now.

I think he traced it to a bad FET on the PA board (Q6101), we did not have any freeze spray unfortunately. Ordered that FET from ICOM and he will replace it.

I do have a breaker in the positive connection of the radio, but it is separate from the panel, with other high amp loads (windless & washdown pump). It shares the large positive cable for the windless which is about 8' directly to the main battery buss and three feet of AWG#10 from the breaker to the radio. The radio negative is a 3' run of AWG#10 to the negative battery bus.

[ka4wja]

JM,
Well, sounds like you're getting things figured out....hope that driver FET was the problem....it's a cheap fix!!

And, sounds like you've got the radio wired properly...so no worries there!

Let us know how it all turns out...

Fair winds...

John

[NahanniV]

I am on the air !

The FET was the problem. A very strange failure mode.

Thanks for all your ideas.

[ka4wja]

JM,
That's awesome!
Glad that you got it fixed....and so cheaply!!

Thanks for coming back and telling us the resolution!!
That is great in two ways....
a) gives us all more data to use, to troubleshoot others' issues in the future...
b) gives us all closure to know that all is good with you...

Fair winds...

And, you should ask the guy that found the problem if he'd mind being recommended for servicing other radios for other sailors, in that area....and if so, post his info here! as we are always in need of good techs/troubleshooters!! (because it's pretty hard o track down a problem from the other side of the keyboard...

John