[ICOM] Fixed! :706 Won't power up remote

[Al Waschka]

In my case it was simple and I should/could have checked it last night if it hadn't been so late.  I looked the the posts (non-moving pins) on the radio end of the cable.  While they didn't appear corroded, they were discolored.  I cleaned them to the point that they were shiny and presto! the radio started working normally.  I guess they got oxidised in the months that the cable was off the radio.
 
The bad news is that somehow in all this my presets got erased so I have to learn how to load the memories all over again.
 
Al


--- On Mon, 8/24/09, Tom Bates <tlbates at lr.net> wrote:


From: Tom Bates <tlbates at lr.net>
Subject: Re:706 Won't power up remote
To: awaschka at bellsouth.net
Cc: icom at mailman.qth.net
Date: Monday, August 24, 2009, 4:46 PM




>>Using the same remote cable I was using in the other vehicle, the radio
>>would not power up. I then realized that I had not put the retaining screw
>>in the radio end of the remote cable so I did that. Now the radio powers
>>up briefly and then shuts off, but I may not have been holding the power
>>button down long enough. If I remove the remote cable and put the
front panel on the radio, it works fine with the temporary power cable
plugged into the dash power outlet. Any ideas why it won't stay powered up
with the remote cable?




Hi again Al.  I'm chasing a similar problem with the exception being that my
706 MK II (not G) will not come on at all.  From the description you gave,
I'm pretty sure your problem is in the spring loaded contacts scheme of
things.

There's only 8 pins leaving the control head and a matching 8 pins going
into the main unit (I also found 8 more spring loaded pins INSIDE the
control head that press onto copper pads of the main circuit board inside
the head- but yours works with just the head alone, right?).

I've heard someone say that the little screw was part of a necessary
electrical circuit.  I don't believe this to be true, but the schematic
doesn't show the extension cable. I suspect it's just there to keep the sets
of pins held together tightly.  If the cable is shielded, then this screw
could be an excellent "one end only" attachment point.  I know that if you
try to store the screw in it's hole after removing the remote cable, the
head won't fit without forcing it!

>From troubleshooting of my own problem so far, it appears to me that MOST
communication between the head and main unit is done with serial comms on
pins 1 (LRXD) and 2 (LTXD).  But it looks like to turn the thing on, ground
from spring loaded pin 5 comes in to the head, goes thru the "on" SPST SMT
switch on front and is sent back out on spring loaded pin 8.  Pin 8 comes
into the main unit on J11 of the main board (thru the little flat 8
conductor cable connecting just above the mechanical filters) and then onto
pin 19 of the IC26 processor.  So, long story short (I think)--to get the
thing to turn on, ground is placed on pin 19 (PWK/PB1/IRQ1) of IC26.

I'm still chasing my own "failure to turn on" problem.  Anyone agree or
disagree with what I've found so far??

Please and Thank You,

Tom - AA1NZ