[ICOM] HM-56 Microphone schematics?

[GGLL]

It has a Lithium battery backup to retain user programmed DTMF tone 
strings stored in mic's memory (cpu inside). Regarding intermittent ptt, 
check the internal electrolytic capacitors inside (there are several) 
for leak; if you attach soldering iron tip to one leg, you may hear a 
"boiling water" like sound and vapour with ammonia like smell. Replace 
the cap so, after cleaning the board with isoprophyl alcohol. Check all 
similar capacitors.
This leak is corrosive and may destroy board traces and through holes.

Best regards
Guillermo - LU8EYW.

W4ABW at aol.com escribió:
> My HM-56 keys the radio too at times. Its very intermittent. I did not know 
> it had a battery. Maybe thats whats wrong with mine ?
> 
> Al
> W4ABW
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