Users may not create topics, posts, or private messages containing or relating to the following material (especially pertaining to Motorola copyrighted software, unless you want Motorola to come along and shut this site down):

  • Listing for sale or trade of, or links to sites offering for sale or trade of, or giving away, Radio
    Service Software (RSS) or Customer Programming Software (CPS)
  • Profanity, pornography, defamation, or slanderous remarks directed towards any individual or entity
  • Commercial advertising (except in the Batboard Vendors forum, as approved by the Admin/Mod Staff)
  • Any other items which may be deemed as offensive

If any topics, posts, or private messages containing or relating to the aforementioned material are brought to the attention of the Admin/Mod Staff, they will be deleted.

Additional FAQ items appear here in Forum Rules. Please review them for posting guidelines and further clarification.

GM300 not recognizing mic as "On Hook"

This forum is for discussions regarding all aspects of Motorola radio programming, including hardware, computers, installation and use of RSS/CPS, firmware upgrades, and troubleshooting. There are subforums for discussions of codeplugs, and also for software/firmware release notes and issues.

Moderator: Queue Moderator

User avatar
KC9MDQ
Posts: 44
Joined: Fri Jul 18, 2014 3:50 pm
What radios do you own?: Motorola,Vertex, Kenwood

GM300 not recognizing mic as "On Hook"

Postby KC9MDQ » Tue Jun 09, 2015 7:53 pm

Howdy gang. I have recently acquired a GM300 from the FD as "payment" for all of Kenwood programming. I have been able to read and write to the radio with no problems whatsoever. The only problem is that when it's on hook, the radio still thinks it's off hook. This means that I'm stuck with carrier squelch, even though PL has been programmed.

Here's all of the data that I can provide. Model number is M43GMC2002AA , serial number is 159TTJ6623 .
It's an eight channel radio, with the masked logic board. It does have a sixteen pin accessory connector. I posted in a Facebook group ( some of you I'm sure are on there and already contributed suggestions), and everyone pointed me to Batlabs and Repeater builder. I found an article in RB about the pins and programming, but all three versions of RSS I've used don't have an option for pin steering or anything. Is this because the software "knows" that the radio has a masked logic board, and so won't even present me with the options?

By the way, I tried contacting pin 14 ( or was it 8 ) to the mic button and I fried the 0 Ohm resistor on the board; I thought I'd bricked it, but I got her up and running by soldering a jumper wire in.

I have tried numerous microphones; I don't know what else to do. I am hesitant to fool around with the accessory connector again, for fear of blowing it up for good.

I have also tried the third party Radio Doctor software, and that makes no difference.

Lastly, I DID play with the "forced monitor" setting in the menus; it made no difference.

Help me, Obi-Wan, you're my only hope !
Powered by Yoyodyne Propulsion Systems

RFguy
Posts: 1354
Joined: Wed Dec 21, 2005 6:17 am

Re: GM300 not recognizing mic as "On Hook"

Postby RFguy » Tue Jun 09, 2015 8:21 pm

Is one of the accessory pins programmed for hook operation? If so, you need to install a jumper, or deprogram that pin.

User avatar
kcbooboo
Batboard $upporter
Posts: 2113
Joined: Wed May 01, 2002 9:03 am

Re: GM300 not recognizing mic as "On Hook"

Postby kcbooboo » Wed Jun 10, 2015 2:34 am

There's a round hang-up "button" on the back of the mike. On some models, you need to ground this to put the radio into coded squelch mode, so the mike clip has to be mounted to a metal surface or you need to run a wire from the clip to ground at the radio. On other mikes the metal in the clip makes a connection between the button and a ground ring behind it, so you just need a metal clip in place. A plastic clip won't do it. You can wrap a metal paper clip a few times around the button to make that connection. That's what I did in my vehicle because I don't have a mike clip mounted anywhere.

You can permanently put the radio in coded squelch mode by soldering a short jumper to the proper wires on the mike jack inside the control head, or do the same thing at the proper pins on the connector at the front of the logic board. The full service manual is available on-line; you can figure out where it is. This is fine for amateur radio use but for commercial use the radio MUST go into carrier squelch mode before you transmit, so you can hear if there's any other activity on the frequency before you use it.

Bob M.

User avatar
jackhackett
Posts: 1463
Joined: Tue Jun 10, 2003 8:52 am

Re: GM300 not recognizing mic as "On Hook"

Postby jackhackett » Wed Jun 10, 2015 9:18 am

I'm guessing the 'zero ohm resistor' you blew is the ignition sense fuse, which would happen if you grounded pin 10.

Masked logic board functions are not programmable like they are on the Expanded Logic board.

On the masked logic board pin 14 is either 'HOOK' or 'PA ENABLE' (for a public address system) depending on a jumper setting. When set to HOOK, grounding it puts the radio into monitor (opposite of the way HOOK from the front panel works). As long as you leave it disconnected it shouldn't affect anything. In other words, don't mess with the accessory connector.

HOOK from the front panel comes from pin 3 of the mic jack, and goes to pin 15 of the J8 control head connector. Grounding this causes the radio to be 'on hook'. The standard GM300 microphone has a set of contacts on it that get shorted together when the mic is hung up, one contact is grounded, one goes to HOOK. Often the contacts go bad, but if you've tried several mics that's probably not the issue unless they are all bad.

You can measure the voltage at pin 15 on J8, it should be around 5V with mic off hook, 0V when on hook.

User avatar
Bill_G
Posts: 3087
Joined: Thu Sep 17, 2009 5:00 am

Re: GM300 not recognizing mic as "On Hook"

Postby Bill_G » Wed Jun 10, 2015 2:17 pm

And it could be that someone pulled the wire to J8, or cut a trace on the vol/mic board.

User avatar
jackhackett
Posts: 1463
Joined: Tue Jun 10, 2003 8:52 am

Re: GM300 not recognizing mic as "On Hook"

Postby jackhackett » Wed Jun 10, 2015 5:15 pm

Bill_G wrote:And it could be that someone pulled the wire to J8, or cut a trace on the vol/mic board.


Or that the mic jack pin is bent, or corroded, or broken. I've seen more than a few radios from fire departments that got water in the mic jack.

User avatar
KC9MDQ
Posts: 44
Joined: Fri Jul 18, 2014 3:50 pm
What radios do you own?: Motorola,Vertex, Kenwood

Re: GM300 not recognizing mic as "On Hook"

Postby KC9MDQ » Wed Jun 10, 2015 8:00 pm

My hanger is mounted to the chassis of the radio by one of the Torx head screws in the side. I've tried the paper clip trick, too. All of the microphones have been tested with my MaxTrac, and are functioning properly. All of the microphone pins are clean and there is no corrosion. I did not see any cut traces, but then again, I wasn't specifically looking for any, either. The radio's previous life was in the cab of a tanker; it's a rather pristine unit, actually. I guess I'll have to tear it down again and investigate. I also have the service manual, but there's so much information in there that my brain almost has a meltdown!
Powered by Yoyodyne Propulsion Systems

Jim202
Posts: 3567
Joined: Sun Sep 09, 2001 4:00 pm

Re: GM300 not recognizing mic as "On Hook"

Postby Jim202 » Thu Jun 11, 2015 5:43 am

It's not hard to look at the monitor pin on the mic connector with a volt meter on the inside of the radio. It should have a positive voltage when off hook. When you ground the mic, it should go to ground.

This doesn't indicate that the radio logic is working correctly, but give you a starting point.

Another point to consider is that the radio is not programmed for tone squelch for the channel your trying to use. You indicated that you can read and write to the radio, but didn't mention that the receive was programmed for tone squelch, unless I missed that point.

User avatar
Bill_G
Posts: 3087
Joined: Thu Sep 17, 2009 5:00 am

Re: GM300 not recognizing mic as "On Hook"

Postby Bill_G » Thu Jun 11, 2015 7:13 am

No, he didn't, but he did say it came off a tanker. I'll assume boat rather than fuel truck. If it was in maritime service, the previous radio tech may have modified the radio to make it permanently carrier squelch.

User avatar
jackhackett
Posts: 1463
Joined: Tue Jun 10, 2003 8:52 am

Re: GM300 not recognizing mic as "On Hook"

Postby jackhackett » Thu Jun 11, 2015 10:43 am

He did say it was programmed for PL.
KC9MDQ wrote: This means that I'm stuck with carrier squelch, even though PL has been programmed.


I would also assume by "the cab of a tanker" he meant a fire department water tanker.

I don't know why anyone in their right mind would physically modify a radio to make it permanently carrier squelch, when you could just program it that way. But then again I've seen a lot of techs that aren't in their right mind, so anything is possible.

At this point I would wait for a report back on what the voltage at J8-15 is doing.

User avatar
KC9MDQ
Posts: 44
Joined: Fri Jul 18, 2014 3:50 pm
What radios do you own?: Motorola,Vertex, Kenwood

Re: GM300 not recognizing mic as "On Hook"

Postby KC9MDQ » Thu Jun 11, 2015 4:16 pm

Sorry folks; I should have clarified: Jack is indeed correct in that it was in my FD tanker. I have tonight left and tomorrow on this jobsite ( a live-in position) and then Saturday off before starting a new job Sunday at 0600. I'll try to check the voltage on Saturday if my daughters leave me alone long enough. In the meantime, I just got another Motorola to play with, but that will be in a separate thread. I appreciate all of the suggestions thus far.
Powered by Yoyodyne Propulsion Systems

User avatar
kcbooboo
Batboard $upporter
Posts: 2113
Joined: Wed May 01, 2002 9:03 am

Re: GM300 not recognizing mic as "On Hook"

Postby kcbooboo » Fri Jun 12, 2015 2:29 am

Those small Torx screws on the sides of the radio are anodized and might not be providing a good ground for the mike clip.

A better ground spot, if the radio isn't mounted, is the bare aluminum mounting area on each side of the radio. Usually you can just touch that area with the hang-up button on the back of the mike and that'll ground it quite nicely. If it Is mounted and the screws are bare steel, that should be a good ground.

But a voltmeter is really the definitive method.

Bob M.

User avatar
KC9MDQ
Posts: 44
Joined: Fri Jul 18, 2014 3:50 pm
What radios do you own?: Motorola,Vertex, Kenwood

Re: GM300 not recognizing mic as "On Hook"

Postby KC9MDQ » Sun Jun 21, 2015 5:12 am

Well, it seems that it's a moot point now. I just received a big box full of GM300's, some 2 channel Radius (Radii ?) And some 2 channel Max Trac 50's. Also a whole bunch of UHF Relm portables. The thread may be locked.

On a side note, all of the 16 channel 300's have the expanded logic board; I didn'the realize that there's so much that these little critters could do!
Powered by Yoyodyne Propulsion Systems

User avatar
MaxK98
Posts: 52
Joined: Thu Feb 02, 2012 8:24 am
What radios do you own?: Lots of Motorola!

Re: GM300 not recognizing mic as "On Hook"

Postby MaxK98 » Sun Jun 21, 2015 7:27 am

You are one lucky guy

User avatar
KC9MDQ
Posts: 44
Joined: Fri Jul 18, 2014 3:50 pm
What radios do you own?: Motorola,Vertex, Kenwood

Re: GM300 not recognizing mic as "On Hook"

Postby KC9MDQ » Tue Jun 23, 2015 9:50 am

Don'the I know it! I just need a UHF 300 and then I can get rid of the garbage TM-V71 (or V7 ? It's that Kenwood with the blue display that gets the lines through it )that's been living in my van for the last three years!
Powered by Yoyodyne Propulsion Systems


Return to “Radio Programming”

Who is online

Users browsing this forum: No registered users and 1 guest