[ICOM] FIXING PW1

[Adam Farson]

Ciao Max,

If you look at the Filter Unit schematic (Service Manual, p. 10-3) you will
see that the relay coil feed circuits are chained. For example, the +12V DC
feed to RL10 (the 7 MHz filter output relay) is routed through the NC
contacts of RL12 (3.5 MHz output) and RL11 (3.5 MHz input). Thus, if RL11 or
RL12 has been damaged in such a way that these contacts are open, RL10 will
not operate and the 7 MHz band will be "dead". 

Another possibility is that the relay driver IC (IC19, Main Unit, p. 10-6)
was also damaged, and that no coil feed voltage is getting through to the
3.5, 7 or 10 MHz relays.  Troubleshooting should not be too difficult.

Cheers for now, 73,
Adam VA7OJ/AB4OJ
  

-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of Massimo 'Max' MUCCI - I8NHJ
Sent: 28 November 2005 00:05
To: ICOM Reflector
Subject: Re[2]: [ICOM] FIXING PW1

Ciao Adam
yes, I checked it with and without ATU. No difference.
I can say what the condition of the failure was. I was running 80 some days
ago with no problems. I run some CQWW on 14 yesterday with no problems too.

Changed to 80 for a while and I discovered the failure.
Thanks, I already download the manual.

I suspect some trouble with the selection relay, maybe there is just 1 relay
for the three bands? No time to look at the schematics yet.
----------------------

73 de Max, I8NHJ/NH7CU



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