Maxtrac logic board swap?

[eagle844]

Hello,

I have a maxtrac 300 vhf radio with a bad logic board 16pin. The logic board is dead and I do not have the codeplug for it.

Can I swap a logic board and reinstall the vhf stuff? Could I use a 800mhz logic board?

Please let me know.

Thanks so much for your input.

Mike

[PETNRDX]

Yes, you can use a Maxtrac ( or Radius "plain", but NOT Radius GM300) of any band VHF hi or lo, UHF or 800 mhz.
You can't use the 900 mhz logic board or any of the GM300 boards.
But, any of the Maxtrac boards can be blanked with Maxtrac LAB, then re-initialized for your radio.
Since you have a dead logic board, you would pretty much have to do an alignment.
If you haven't already, go to the Repeater-Builder website and read the Maxtrac articles.
They are very helpful on this topic.

[eagle844]

Ok, thanks. I cannot seem to find that article about alignment. Could you please post a link and you say i can use the 800mhz board. I see 2 channel 800's on ebay for nearly nothing. does that board have the capacity to hold 16 channels? If not, what do I need to look for?

Thanks so much for all your help.

[Satelite]

Hello:
If the radio is completely dead as in nothing operates then check into replacing the logic bds fuse before blanking and replacing the bd ect.
Satelite

[eagle844]

Yes the radio is dead and shows a short on the board with a blown 100uf cap. I replaced the cap and still a dead short/

Also, will 2ch 800 maxtracs logic board hold 16 channels?
Is the firmware chip were the channels are stored?

I do not want to buy an 800 maxtrac to find out the channel capacity will not hold my original 16.

Thanks so much for you help.

[eagle844]

First I would like to thank the people for the responses. All this could not be done with you knowledgeable people out there helping others. THANK YOU!


I have been doing a ton of reading. My eyes are burning for two days now.
From the info that I have been reading, the logic board can be swapped. The 5569 chip is the firmware. Is that the “EPROM” that holds the band, channel capacity, frequencies, and the workings of the radio. The logic board is just the hardware like a motherboard in a computer. So, the 5569 is a “hard drive/ROM” with the radio “OS” sort of speak like windows? Is this right? The RF board determines the band of the radio which it can operate in?

So at this point, my understanding is a logic board swap and place my 5569 chip in the new logic board would revive the radio. Now on to the alignment. I have read the articles about the alignment but I lack the service monitor. What can I do to align the radio without that?

I do not have a saved codeplug. The radio is dead and there is a blown 1000uf cap. I replaced the cap and still there is a dead short. I could not get the codeplug or anything from the radio. This looks like a fresh start. Do I take all the info from the RF board and put into the RSS LAB?

I do not have another logic board yet. Does the 800mhz maxtracs have the same logic board and just a different “firmware/EPROM” chip that can be swapped? Is there several different boards I need to stay away from because it does trunking only?

I am at a loss. I am new to the Motorola thing. Please forgive me for that.

Thanks for all your responses.

[Will]

Yes the radio is dead and shows a short on the board with a blown 100uf cap. I replaced the cap and still a dead short/.

I could be a shorted transistor in the audio output amp stage.

[Jim202]

Is there any chance the radio power feed was connected backwards recently?

I believe there should be a reverse polarity diode to protect the radio from just this problem. When it does happen, the diode normally shorts. I work on so many different radios, that I can't remember the Maxtrac clearly. Been a few years since I have spent much time inside them.

Jim

[eagle844]

No, it was hooked up correctly. I used a different accessory connector that was from another moto. I realized it after it blew the cap. it was wired 16 & 13, so it shorted and blew the cap. I did did some testing to narrow down the problem. i tested with just the PA connected and was good. Then PA with logic=dead short---both with rf board connected and not, as well with the head and not.

So I guess I am down to a logic replacement. I cannot work on surface mount stuff its just too small for me.

Thanks for the reply.

[com501]

Remove the Audio PA and see if your short goes away....

[eagle844]

What is the audio PA?

Is that all the transistors on the side?

Please advise.

Thanks a ton