ICOM 710RT Transmit Issue

[belizesailor]

Today, for the first time in almost 20 years, my good old 710RT had a problem. When attempting to transmit I could not be understood (lots of noise, clipping?). I was told later the signal was strong, but audio unintelligible. "Error" would flash on the screen if I tried to transmit for more than a few seconds.

Reception was fine.

I suspected it might be a microphone issue so removed to test (pins at connector looked fine, no corrosion etc). Opened it up. No obvious problems inside (nothing fried, solder connection to PCB look good). Tested from male pins to wire connections on PCB. Results below.

Ideas? Suggestions?

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ICOM Mic Test

NC = "no connection" to any wire lead test point on PCB

PTT switch tests good at BLK & RED solder points on PCB.

Pin
1 - YEL (MIC+)
2 - GRN (?, manual shows NC)
3 - NC
4 - NC
5 - NC
6 - MIC-, SHLD, BLK, BRN (note: point BRN has no wire connected)
7 - MIC-, SHLD, BLK, BRN
8 - NC

Very low ohms on all tests above.

R1 tests at about 1K ohms, but no continuity on R2 - R4 (?, will clean contact points and test again).

[belizesailor]

Whew, just a bit of a bad connection at the mic connection apparently. Cleaned it up and now working fine. First time I've disconnected it in almost 20 years so probably due for a little cleaning anyway.

Good thing I wasn't relying on you guys...no response at all ! ;-)

[Freedom45]

Originally Posted by belizesailor

Good thing I wasn't relying on you guys...no response at all ! ;-)

Try cleaning the mic connection

[belizesailor]

Turned out it was a bad connection, but not at the mic. It was the power connection to the remote head. Bit of gunk in this connection, cleaned it up (and all other connections) and all is well.

This simple solution of course found after half uninstalling the system to get at every other connection and fuse (one is inside the transceiver).