N1GY- The simple Approach to Ham Radio

Wiring Color Code and Pinouts for IC-706MkIIG and HM-103 Mic

I had to research this info recently so here it is for others to ponder.

Wiring Color Code and Pinouts
Icom HM-103 Hand Mic.
Used on IC-703, IC-706 all models, IC-2000, IC-2000H
NOTE: View RJ-45 Connector with the locking catch away from you and contacts  up. This will orient pins as shown in diagram below. 
HM-103
​See lower diagram below 
Pin 1-    8 VDC+       Red (May not be present. If so then N/C) 
Pin 2-     UP/DOWN   Black 
Pin 3-     AF out          N/C 
Pin 4-     PTT             Green 
Pin 5-      Mic Gnd       Shield (Black #2) 
Pin 6-      Mic +           White 
Pin 7-      Ground         Blue 
Pin 8-      Squelch        N/C 
CAT5 (568B)
See first diagram to right 
Pin 1-            Orange/White 
Pin 2-            Orange 
Pin 3-            Green/White 
Pin 4-            Blue 
Pin 5-            Blue/White 
Pin 6-            Green 
Pin 7-            Brown/White 
Pin 8-            Brown 

​ The above diagram shows the color code and pin-out for CAT-5 connectors used in computer networking. Cross-reference the HM-103 data to position the wires properly in the new RJ-45 connector.Below is the RJ-45 in the same orientation as the regular CAT-5 plug, but with the color codes for the HM-103 Hand Mic. Ignore the reference to "568B" under the bottom illustration. Note that three pins, 1, 3, and 8 may have no wires present. The HM-103 only uses 2, 4, 5, 6, and 7. Pin 1 may have a red wire present in the RJ-45 but it is not used inside the mic itself. Pin 5 (the second black in the color code) is where the shield gets attached. The supplier apparently added a short wire "tail" to the shield to place it in the RJ-45. This wire was insulated with a black sheath. Do not attempt to insert the shield directly into the RJ-45. I once purchased a mic from an overseas supplier who had done this and within a few weeks the shield had shorted to the mic + pin next to it and I had to repair that connector all over again. Please note, This color code may be different on your mic. I am led to believe that Icom used several different suppliers for their mic cords. Not all had the same color code. Be sure to check your mic against this code and note any differences.      I was unable to position the illustration of the RJ-45 exactly where I wanted to, but you get the idea. Pin 5 is where the shield goes, but you will probably have to solder a short length of wire to the shield to get it to fit inside the RJ-45. Use a fine soldering tip and keep the joint small and smooth or it will not fit.      An alternative solution is to cut about 4" off the end of a CAT-5 jumper that already has an RJ-45 installed on the end. Then using the color codes and pin positions shown above, splice each wire from the HM-103 to its matching wire in the CAT-5 cable pigtail. Reinforce the splice as necessary and plug it back into the radio. If you have done the splicing correctly, it will work.      Please note, these instructions are (as usual) not guaranteed in any way. Perform this work at your own risk. Any errors in wiring may cause significant damage to your rig.

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