Cleaning/Repairing GP300 speakermic jacks (and speakermics)

[VA3XDJ]

Hi gang,

I've never taken my GP300s apart even though curiosity has tempted me.

I need to clean/realign the contacts on the speakermic jacks.

Speaker audio comes out fine but microphone/ptt is a little fussy.

I'm pretty sure its from the environment the radios were used in beforehand (one at various sites on rental and the other at an arena) so dust or other debris has settled in there preventing a good contact.

Can someone give me some tips and assistance? I've seen my tech take them apart by removing the knobs but haven't had a reason to take them apart yet.

I'll call long distance or DC (Nextel/Telus) for a walkthrough if it makes things easier.

Thanks in advance.

[EKLB]

Remove the volume and ch knobs by pulling up and off of there control studs.

Remove battery.

At the back side of the radio at the bottom take a small screw driver and gently pry the bottom plastic out a little bit to clear the two snap in retainer slots and the radio should pull up and out of the plastic case away from the chassis.

But dont pull apart too far until you unplug the now exposed speaker/mike flex from the bd.

Then continue to pull up and slide the top vol and ch control studs down and out of the case.

You should now have the two seperated = There will be four small L shape bent clips you can pry off to get the rest to seperate.

As for the Mike/Speaker jack cleaning i spray electrical contact cleaner into each jack and then work a mike jack conector in and out a few times then with LOW AIR PRESSURE i blow the remaining spray solvent out and dry by the air .

DONT USE 120 pounds of direct air pressure or youll blow the jack apart.

If you use high pressure then at least stay back aways and spray the air into the jack openings from a distance to reduce the inside jacks air pressure.

EKLB

[Dave]

The best thing to do is to replace the jack. Cleaning the jack will only help for a short time.

Now, getting the old one out and putting the new one in is kind of like a puzzle.....but it is possible. Maybe your tech can help with that.

[VA3XDJ]

Thanks for all the info.

Turns out one of the mics has a short in the PTT line, which, I'm guessing, might be an inversed polarity in the wiring of the mic head.

I posted another topic in regards to this. I'm looking for the wire color/pinout for the small pc board inside the speakermic head. Model is HMN9725C

[Al]

The service manual doesn't show the physical wire connections, I pulled a defuncgt HMN9725D apart to get the info you requested: If you view the small PC board in its normal position inside the housing, there are four pads along the bottom(coilcord exit side of the RSM. The first, nearest the front of the housing is red(with 1 purple from the same PC land to one side of the speaker); the next from the front is black, third is blue, and the one nearest the housing back cover is white.

[VA3XDJ]

Thanks alot for your help Al, the wiring matches your description.

It must be the capacitors. The speaker audio works fine, but as soon as I plug in the speakermic (while radio is on) the radio stays keyed and if I plug it in while radio is off, no PTT at all. And audio from radio and mic is very dim if you blow into the mics.

I thought it may be a polarity issue but the wiring matches up.

If monitor/vol set is held while PTT is pressed, it has a sounds similar to scan.

Make any sense?

Thanks again.

[richyradio]

....not long ago, I set somebody up w/ a bunch of gp-300's...I 'kinda like them, relatively simple, reliable...(well' here's the point) they all worked great for about one month , then, amazing to me, they all rapidly failed at the exact same time- they all lost either rcv or xmit audio, or both....these are in service on an east coast beach area, i.e. at most, 4 months in service each year, albeit in a corrosive atmosphere....long story short, in every single case, it was the speaker/mic jack that failed, and spkr/ mics are not used...upon working on a dozen or so units, I noticed that a number of them were replaced, and the repair job was questionable....( looking at the assembly of the unit, they don't lend themselves to easy repair) other ones original, equally as crappy....so I guess the point I'm trying to make is that the jack design is a piece of sh*t and if you don't need it, just bypass the thing, which unfortunately, is no easy proposition either...(tacking to those little chokes, if you know what I mean) I think this is why they changed that whole arrangement in the gp-350.....(I hate the looks/feel of a '350!)

[VA3XDJ]

Allrighty then!

The jacks on both radios work fine as it is (I've tested them with my working speakermic) so it wasn't the radios.

I don't like the look and feel of the GP350s either, and they were more expensive so I opted for the GP300s (245$ CDN used with new battery, antenna and charger) and I like them alot more than my old HT600s and MT1000s.

In any case, I gave the speakermic to a friend so he could recase the shell on his (my old) MT1000 speakermic which has taken a beating after being rolled over with a bike -- The mic clip came loose and the mic ended up under the back wheel and cracked all over.

We do bike trail patrol on a voluntary basis during the summer season and the city is so broke, they gave us inactive cell phones to call 911 with. I don't think so!

So I use my GP300s and the others use the HT600s and MT1000s along with some Motorola T5500's (GMRS) so if anyone is in trouble, we can bring a first aid or repair kit faster than waiting for someone to run into the paths and look for us.

It just helps having a speakermic rather than removing the radio from the belt everytime a call is made/received.

If someone has a USED but WORKING speakermic to get rid of, I would definitely like to hear from them.

Thanks