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Old February 21st 04, 11:38 PM
Mark Keith
 
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(Dave Platt) wrote in message ...
Anyone ever have a problem with a Icom 706MKIIG not turning on? I
checked voltage inside the unit and it shows 14 v up through the
internal fuse section.
I own 2 Icom 706mkiig and this newer model just would shut off while
attempting to Tx in the other vehicle where the older 706 mkiig works
flawlessly.
Of course the warranty just expired


I have one and sometimes it will not come on in the house. It seems that
when I turn on the power supply then try to turn on the Icom , it will not
come on. If I unplug the Icom and plug it back to the 12 volt supply it
will come on and work fine. Not sure if the voltage comming up slow has
something to do with that or not. It just started doing it after about 2
years. All the other rigs work fine from the same Astron 50 amp supply,
including a Yeasu 757.


In the case of the rig which shuts itself down when transmitting - are
you measuring the voltage inside the rig when the rig is off, or when
receiving, or also when trying to transmit into a dummy load?

If there's a bad fuse, switch, or connection somewhere, the voltage drop
from the fault might be relatively low when only a small amount of
current is being drawn - with the rig off, it might read full battery
voltage. When the rig tries to draw more current through the high-Z
fault, the voltage drop in the fault might reduce the voltage seen by
the rig's circuitry enough to result in a "low voltage" safety
shutdown (or failure to start up).

Try putting a 'scope on one of the 14-volt-rail test points on one of
the rig's PC boards, and see if [1] the voltage is getting through OK
with the rig off, and [2] if the voltage drops abruptly for a moment
when you try to power on.


I agree. I notice the 706g is very prone to shutting off if the
voltage drops. I think it's a protection scheme of sorts...Note that
it will always shut off for a second when starting the engine, even if
the wiring is straight to the battery. "Or at least mine always has".
Also, if you run a battery down low, it has the quirk of shutting off
and on, off and on, forever until you notice it and turn it off. I've
had this happen when I forgot to plug the charger in, and the battery
got low. Click, click...click, click....click, click....No telling how
long it did that before I noticed it...Didn't seem to hurt it
though...
Gotta a funky power connection, corrosion, loose, or cold solder joint
in the rig I bet somewhere. Need to find the point in the power trail
that you see the large voltage drop on transmit. I'd start from the
supply, and work back to the rig until you find it. BTW, if using a
supply in the house, I'd always prefer to power the supply up first,
and then turn the radio on. Here, I use battery power and a charger
even in the house. Mine is on nearly 24/7...Hardly ever turn it off,
unless it to put it in the truck. Mine is three years old. MK