Icom 400 microphone

Submitted: Saturday, Dec 14, 2019 at 12:21
ThreadID: 139421 Views:3784 Replies:7 FollowUps:9
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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.



Any help would be appreciated.

Thanks
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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.
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Reply By: Member - ACD 1 - Saturday, Dec 14, 2019 at 14:25

Saturday, Dec 14, 2019 at 14:25
Pretty sure it connects to the small metal button that clips into the mike mount on your dash - think it's refered to as the hanger.

Some radios have a "hook" feature which sends signals to the radio to let it know if the mike is hanging up.

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Anthony
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Reply By: Member BarryG - Sunday, Dec 15, 2019 at 09:21

Sunday, Dec 15, 2019 at 09:21
I agree, probably needs to be connected to the hanger which should be earthed.
Some further info here

Barry
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Reply By: Allan B (Sunshine Coast) - Sunday, Dec 15, 2019 at 10:40

Sunday, Dec 15, 2019 at 10:40
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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.

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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.
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Follow Up By: Allan B (Sunshine Coast) - Sunday, Dec 15, 2019 at 16:02

Sunday, Dec 15, 2019 at 16:02
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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?


Cheers
Allan

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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.)
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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.
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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.
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Reply By: Seacay - Monday, Dec 16, 2019 at 18:30

Monday, Dec 16, 2019 at 18:30
Yes it is a 400Pro. I thought I would take the cheaper option and purchase on eBay, should have gone straight to dealer for spares.
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Follow Up By: Seacay - Tuesday, Dec 17, 2019 at 14:52

Tuesday, Dec 17, 2019 at 14:52
Have just rang the dealer, apparently they don't supply cable only complete new microphone at $80. Disappointing as you can replace the whole unit for $300 to $400, depending where you shop.
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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Dec 17, 2019 at 15:21

Tuesday, Dec 17, 2019 at 15:21
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You can buy a complete new microphone here for $36.
Cheers
Allan

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Follow Up By: Seacay - Tuesday, Dec 17, 2019 at 17:29

Tuesday, Dec 17, 2019 at 17:29
Thanks Allan, I have seen that.

Whilst it notes the 400pro in the heading it does not appear in the compatibility listing, that is where I went wrong with the first purchase.
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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Dec 17, 2019 at 18:28

Tuesday, Dec 17, 2019 at 18:28
.
You're right Seacay. I had not seen the compatibility list.
Furthermore, I spotted this in the reviews... "Does not work with Icom 400 pro".
Sorry.
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Allan

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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?
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