Follow Up Icom Marine Radio

Hi All this is a follow up to the ICOM Marine Radio IC-M45. Overall it was a success! Another boat anchor saved, total parts cost under $5.

Replaced the reverse protection diode 1N5408 and the audio amp LA4425 and were up and running again! Below are some picture of the repair.

here is a link to the service manual . I had to look up a replacement part number for the diode since there where no markings.

New audio amp is on the left corner 

New LA4425, don't forget the heat sink clamp! 

Front shot before cleaning 

Careful with the flat cable, the glue holding the plastic stiffener tends to dry out.

Disassembled ready to clean 

Replaced reverse protection diode and repaired cooked trace

Bad Diode, man his is old! Who make this package anymore?

 Assembled and cleaned, looks good!

Icom Marine Radio


I was asked by a friend to troubleshoot a marine band radio. Opened up the radio and found a open trace. To the left of the red wire is the reverse protection diode (shorted), I cut the diode out, soldered the trace back and it powered up! But no audio was coming out, to the right of the red wire you can see another trace leading to the audio amp, I used a signal tracer (Heathkit 5283) and found the input to the amp was working fine, the amp is a LA4425. It's been discontinued but I found a few on ebay from around $1.50 Each. Come to find out the radio was hook up with reverse polarity with no fuses. Just waiting on the LA4425 to come in from china. I used a 1N5408 to replace the reverse protection diode.

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