icom HM-100N mic

[m3vuv]

Hi all,ive an icom ic-f1010 on 2 meters,the mic seems to of given up the ghost,would anyone have a schematic for one,ive hunted all over but cant find anything,its funny it says condenser microphone on the rear but has a 5v feed to it.!TIA

[m3vuv]

sorry,i was getting mixed up with dynamic!,all i get is a carrier but no audio.

[Wallace Gasiewicz]

I fix mics all the time at a radio shop
Mostly the problem is a bad connection at the connector going into the radio.
This is most likely an Electret condenser mic, almost everything is these days, they take 5-9 volts "phantom" power
Electret capsules are interchangeable (2 pin or 3 pin)

[m3vuv]

I see a trace on the scope with audio from one side of the mic element and ground but nothing at the mic wire out where the wires are soldered onto the pcb,found a 2.2k resistor open,renewed that,now as soon as i connect the ground wire to the mic ,i get no tx audio and the radio goes into prog mode!,think maybe the issue is in the radio?,would try another mic if i can find the mic schematic,but no luck yet finding one!.

[m3vuv]

Its been a few years ago but,if i remember rightly this was hooked up to a psu that went full output,think its gone into prog mode with a mic plugged in since,the rx is good and the vfp etc,just no audio!.

[m3vuv]

Well i traced the mice output to,the main board,it goes to an ic (25 on the schematic),its listed as  TC4W66FU (TE12L),looked it up,looks like a dual bi lateral switch,any idea what that does in a mic circuit and could that be the problem,just been to see a friend who has a spare mic to test but he is out,will try tonight.

[Wallace Gasiewicz]

Here is the Service Manual

https://www.manualslib.com/manual/919184/Icom-Ic-F1010.html?page=42#manual

I do not know what "resistor" you replaced. There is a 1 uH inductor in the mic audio lead. in the front unit.
Go to page 42 of the manual. You can check some of the mic  leads especially the power lead (VCC) 5V.

IC 25 is on page 54.

I did not look but is there a back up battery for the memory?

[m3vuv]

ive traced the signals thry to ic s5 ,it stops there!,i assume its dead but cant find a replacement,i have the service manual .

[Wallace Gasiewicz]

Try Ebay UK

This is from a US search: chip is in UK

https://www.ebay.com/itm/254257659513?epid=1462592037&hash=item3b32effe79:g:8CIAAOSwk8xc-7V,