Icom 400 microphone
Submitted: Saturday, Dec 14, 2019 at 12:21
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139421
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Seacay
Hi all, l have a icom 400 cb installed in my vehicle and the Mic cable required replacement. I disassembled the mic then purchased a new cable. Unfortunately I never take a photo before disassembly and now cannot remember when the
grey cable was attached.
Icom mic HM-152
Any help would be appreciated.
Thanks
Reply By: Frank P (NSW) - Saturday, Dec 14, 2019 at 14:12
Saturday, Dec 14, 2019 at 14:12
I found a wiring diagram on the last page of
this document.
If anyone can interpret that they may be able to help.
I suspect that with the big screw eye it will go to one of the cover screws and is electrically not connected to anything, but that's just a guess.
Another guess - does it go on the screw that holds the hangar button on the back cover? (See the black box at the bottom right of the circuit diagram)
EDIT: ACD1 said that in his reply below as I was editing this to say the same thing.
AnswerID:
629084
Reply By: Allan B (Sunshine Coast) - Sunday, Dec 15, 2019 at 10:40
Sunday, Dec 15, 2019 at 10:40
.
That lug, with its attached wire, goes under the screw that secures the hanger button on the rear of the mic.
It is only used with certain models which provide the following functions:
- Automatic scan start when on hook.
- Automatic priority channel selection when off hook.
- Sets to ‘Inaudible’ condition (mute condition) when on hook.
- Sets to ‘Audible’ condition (unmute condition) when off hook.
The hook itself needs to be earthed for this to operate. I doubt that it is an available function in your model radio. But attach the lug anyway to keep it out of harms way.
ICOM HM152T Hanger Connection
AnswerID:
629091
Follow Up By: JohnnyC - Sunday, Dec 15, 2019 at 14:16
Sunday, Dec 15, 2019 at 14:16
Allen is quite correct, most CB radios are capable of CTCSS operation, that's where the transmission has a subaudible tone that is required to open the CTCSS squelch, so that you will only hear transmissions from another radio that is sending your tone, that way you don't have to listen to other annoying traffic.
However when you want to transmit you must first disable the CTCSS to ensure that the channel is not busy, when you pull the mic out of its hanger it removes the ground from the lug on the mic and disables the tone squelch, reverting to the more usual carrier squelch which opens on any transmission.
FollowupID:
903793
Follow Up By: Allan B (Sunshine Coast) - Sunday, Dec 15, 2019 at 16:02
Sunday, Dec 15, 2019 at 16:02
.
Johnny,
Only certain radio models (e.g. IC-400-PRO) supported this feature.
Did the feature operate before the microphone replacement?
The microphone assembly needs to be type HM-152T.
The replacement cable needs to be correct for HM-152T.
Is your hanger correctly earthed as per the diagram below or by being screwed to an earthed metal panel?
Mic. hanger connection
FollowupID:
903795
Reply By: Seacay - Sunday, Dec 15, 2019 at 15:22
Sunday, Dec 15, 2019 at 15:22
Thanks all for your input. I figured it had something to do with the earth lug. I have connected it to the hanger but it still will not scan when on hook, guess I'll have to go to a dealer.
I have reassembled using the original damaged cable and all is working
well again. Seems the purchased cable is not, as claimed, suitable for the unit.
AnswerID:
629094
Follow Up By: Frank P (NSW) - Monday, Dec 16, 2019 at 16:48
Monday, Dec 16, 2019 at 16:48
Have you tried contacting
iCom Support?
According to the table, the 400 Pro is still supported. (Is yours a 400 Pro? I have not been able to find a reference to a straight 400 anywhere, only 400 Pro.)
FollowupID:
903829
Follow Up By: Zippo - Tuesday, Dec 17, 2019 at 18:02
Tuesday, Dec 17, 2019 at 18:02
We are left to presume that your hanger is actually earthed AND the unit did scan-on-hook previously.
FollowupID:
903862
Follow Up By: Seacay - Tuesday, Dec 17, 2019 at 18:55
Tuesday, Dec 17, 2019 at 18:55
Yes the 400Pro does have the on hook open scan function and did work prior to the replacement cable.
Thanks again for your assistance.
FollowupID:
903866
Reply By: RMD - Thursday, Dec 19, 2019 at 19:49
Thursday, Dec 19, 2019 at 19:49
Seacay
I am a bit mystified as to the wire lug pictured would have to been unscrewed from the only screw inside the back half. Isn't it very straightforward that is where it would have to been returned to. If the new cable is electrically the same as the original with same plugs both ends, it must therefore work the same and the
grey wire in it's original spot, all would be as original with regard to operation, wouldn't it?
AnswerID:
629151