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.
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.
NC = "no connection" to any wire lead test point on PCB
PTT switch tests good at BLK & RED solder points on PCB.
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).