Batboard

So, to replace my GM300 as a beater truck radio, I picked up a four channel M1225. I have played with one of these that was the twenty channel version with the nice alpha display. What I can't figure out, is that the four channel radio has audio that can only be described as "tinny" . I pulled it apart and cleaned the cone and the speaker grille, thinking that perhaps the cone wasn't able to flex, but it looks alright. Unlike CDM's or Tracs, I have had limited experience with the R series. Do the four channel models typically just sound cheaper than their more expensive counterpart ?


Also, for what it's worth, this particular radio's past life was spent in the cab of an agricultural tractor. I did a lot of cleaning on the board.

I think the marketing dept called it "crisp" sounding. They are not thundering fer sure. Considering it's history, it may be toast. They probably had it at full blast all the time. You can always put an external speaker on it.

Bill_G wrote: You can always put an external speaker on it.

A good way to see if the internal speaker is bad. Bill G gets a star.......

The external speaker would be pins #1 and #16, correct? Slightly hesitant on fooling around with the accessory connector since I (almost) bricked my GM300. Pin #1 would be top left-most pin and #16 would be bottom right? ( I'm looking at the diagram on the connector page and from the description it looks like I need to "flip" that picture.)

Okay, I'm finding conflicting information and diagrams on the pinout of this radio. Can anyone who actually HAS ONE describe the location of pin #1 and #16 so I don't fry this thing? Description wise, I mean while looking at the back of the radio itself, not the mating end of the connector.

It has always been a bit confusing. Using the image for orientation, the big plastic tab is up. It lays against the heat sink. Pins 2-16 are left to right along the plastic tab above the odd number row.

Bill_G wrote:It has always been a bit confusing. Using the image for orientation, the big plastic tab is up. It lays against the heat sink. Pins 2-16 are left to right along the plastic tab above the odd number row.

That diagram is for a Maxtrac. He is asking about an M1225 which has the connector flipped upside down from that.
Luckily, if he actually used that the speaker pins would still be in the same places just with 16 and 1 switched, but the other pins would be wrong

This is the one for the M1225


Also, if you have the correct plug, it is marked with pin numbers on one side.

Edit: Also, the service manual (which has nice pictures of the pinout) is available on that repeater site we all know and love.

Maxtrac or M1225 - they're exactly the same. Even your drawing bears that out.

Or have I been wrong for years? I've never noticed a difference, or had a problem.

Bill_G wrote:Maxtrac or M1225 - they're exactly the same. Even your drawing bears that out.

Or have I been wrong for years? I've never noticed a difference, or had a problem.

Well if you look at the maxtrac connector drawing it shows the even numbered pins at the top of the radio, on the m1225 the odd numbered pins are on top. So if you went by the maxtrac drawing and stuck an ignition sense wire on where it shows pin 10 you'd actually be putting it on pin 7 which is ground. That would give an unexpected and unpleasant result.

Check your programming. Make sure companding is turned off. Also check to see if you have emphasis and de-emphasis turned on. All the radio in the fleet need to be programmed the same way. If your current radios don't have emphasis and de-emphasis on then this radio needs to have those settings turned off. Then again, who knows, it might sound better with it turned on too. Also check to see if there is an audio processing filter option and disable that too.

jackhackett wrote:

Bill_G wrote:Maxtrac or M1225 - they're exactly the same. Even your drawing bears that out.

Or have I been wrong for years? I've never noticed a difference, or had a problem.

Well if you look at the maxtrac connector drawing it shows the even numbered pins at the top of the radio, on the m1225 the odd numbered pins are on top. So if you went by the maxtrac drawing and stuck an ignition sense wire on where it shows pin 10 you'd actually be putting it on pin 7 which is ground. That would give an unexpected and unpleasant result.

Ah! Got it. Thanks.

So with the diagram a few posts above, am I correct in that it is showing the male end of the plug as though you were "looking" from the receptacle on the back of the radio?

Yes. If you place the radio on a table right side up and look at it from the rear the pins in the radio connector are numbered as shown in the picture I posted.

Also check your Private messages.