ARCHIVE: Australian Ham Radio Discussion Forum ( AHRDF )

During the JMMFD over the weekend, I encountered an unusual fault : the Icom 7400 went dead when I was transmitting. The AC power supply was still on and producing 13.8V so it was a bit intriguing.

When I moved the DC power lead to the back of the radio, power returned.  The fuseholder for the positive supply was quite hot so I opened up the clam-shell holder and discovered that the incoming wires are simply crimped. Using a screwdriver from the actual copper conductor to the fuse end connector returned the DC power.

I took the power lead off, soldered the previously-just-crimped connection and the radio ran faultlessly for the remainder of the event and was producing a higher RF transmit power than earlier. The fuseholder was also quite cool, even with high duty cycle transmit.

If you have the Icom-supplied power leads with the in-line fuseholders shown in the image below, take a few minutes to solder each crimp connection - it might save you a lot of aggravation.

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The fuseholders in the 6 pin power lead - the partially-visible clamp-on ferrite is my addition

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Solder each end where the crimps are. Red arrows indicate approx positions.

From memory these types of fuse holders  on icom rigs and maybe others have had a similar problem for years.

I have seen similar reports in rig yahoo groups, even fairly recently

Also the part that actually holds the fuse can get dirty etc and require cleaning... nothing like nice clean contacts HI