IC-208H Xmit issues

[axm1955]

Afternoon all,

Just bought the above from a friend who took extremely good care of it since original purchase.
My issue is this: The radio was working perfect on my way in to work Monday morning, removed the face plate (of course after shutting the unit off) and mike when I parked the car (this is to keep low budget shoppers from damaging the car to get to the unit). When I returned around 4pm and reconnected all the pieces together I no longer had back light on the mike and it will not xmit. The radio receives perfectly, can change settings from the front panel fine, but the mike functions no longer work.

Any ideas as to where I should look for possible culprits? I am well versed on radio repair and have downloaded the service manual for it, just asking for input before delving into a full blown repair adventure.

Thanks for any helpful input/information.

73
Adriano

 

[fineshot1]

Sounds like a mic logic problem. If you can obtain another mic(they are cheap on ebay) and swap first I would start their. Not sure but its(the mic) probably not repairable unless you are equipped and knowledgeable in repairing smt technology. Its also possible its just a bad crimp connection on the mic rj45 connector. Good luck & let us know how you make out.

 

[mancow]

I would guess that it's a bad ground line or bad + voltage line to the mic since the backlight is out. Did you check all your pins and contacts to make sure everything is normal?

 

[axm1955]

Hello and tanks to both replies.

Yes I did ohm out the cable (pin to pin) and it appears to be OK, or at least at the low voltage and current of the ohm-meter it measured OK. I did contact a friend who has a 706MK with a 118N installed on it (the non intelligent mike) and I'm in the process of getting with him to try this out....the paths to repair the 133 do not appear to be simple since a "proper schematic for it has yet to be located".

If anyone out there has access to Icom schematics for the 133, please post a reply.

Regards and 73

Adriano

 

[fineshot1]

Fyi

There are several slightly different versions of this microphone. I do not know what the difference is.

HM-133, HM-133V, HM-133S

 

[CCHLLM]

I've got two ICOMs that have the 133 mic, and each works just fine on either radio. The only difference I can see between two of the versions I have (133 and 133V) is simply the labels on the buttons. This would account for two model numbers in the scheme of manufacturing things that are different, if different only by functional labeling.

 

[n1das]

I forget exactly which pin it is but do you have +8V at the mic connector on the radio? The HM-133 schematic should help you find the +8V pin in the connector.

Good luck.

 

[jonny290]

Hint: You can replace the HM-133 cable with any standard straight-through Ethernet cable to test it. The mic has a little plastic notch on the back, down where the mic cable goes in - stick a little screwdriver or key in there to push the tab down, pull the cord out.

My HM-133 cable went south a while ago. Replaced it with a 15 foot CAT5 cable and cannot tell the difference (this is a mobile install, too).