Strange Maxtrac 300 Problem

[Vercomm]

I have recently pulled a maxtrac out of service due to some upgrades, but they guys want to re-use it, but it has a strange porblem.

Maxtrac 300, VHF, 25watt, 146-174MHz, 5 pin Acc

When the radio powers on it emits a continuous tone for approximately 5 seconds. After that the radio is 100% functional. If the power is removed for only a couple seconds and then turned on it won't emit the tone and is 100% functional.

Any ideas on what's going on?

Thanks,

Jamie

[Al]

Corrupt codeplug, if the tone is a low frequency(about 300 hz).

[Vercomm]

Hey Al,

I'm not sure if it's that low, but I check it out. Are there any other possibilities?

How can you go through the codeplug and find out what is corrupted? Or what would you suggest doing in order to cure the problem?

Jamie

[Max-trac]

Per the service manual;
900 Hz (short beep, 119 ms) = normal,
163 Hz long (5 sec) = codeplug error
300 Hz short (200 ms) when button is pressed= feature not available.
150 Hz or 112.5 Hz when PTT pressed = ptt not allowed.

Check your power supply voltage.
Watch the 9.6V voltage as you do your mentioned power cycles, (middle pin on the pins that go thru to the other side of the radio).
Re-seat the eprom firmware (if applicable).
Try re-loading your archived codeplug.
Read then write back to the radio if no saved codeplug availble.
Blank, initialize and align.

[jackhackett]

Look and see if it has one of the old Dallas NOVRAM chips, some of the older Maxtracs used these instead of EEPROM. They're basically some RAM with a lithium battery, any of these still around are probably old enough that the battery is at the end of it's life expectancy.

[Rayjk110]

One of my VHF MaxTracs used to do something similar; I had found out later via further cpg investigation that some emergency sense thing was enabled?

Wasn't ignition sense, but some sort of remote or local emergency ptt thingy. Altho mine is a 16 pin, so I suppose that makes a difference.

[Vercomm]

Here's the info from inside the radio:

It does have the Dallas DS1220Y Nonvolatile SRAM. So what should I do know, replace the SRAM with an EEPROM?

What the best course of action?


FYI, the model number of this particular radio is D33MJA7DA5AK, serial # 428FNA****. Looks like the radio is 1988 vintage.


Jamie

[RFguy]

Sorry to move off topic and wander down memory lane, but....

Wow. Almost 20 years old. I can remember the day we got the first Maxtrac in the shop (shortly after was the HT600). We went out and bought the shop's first computer. We bought the big 20 Meg hard drive instead of the 10 Meg, so we would NEVER have to upgrade.

[Max-trac]

Good call JackHackett, I forgot about those, that is probably it.
I think you can put in a 28C16 in it's place, not sure if you need to change any jumpers on the back of the board.
Make sure you have a saved codeplug to load into it.

OR just get a cheap 800 Maxtrac with the 16pin board and make it a 32ch full featured unit.

[ard099]

Check the transmit power output. If more than it should be turn the transmit power back down to rated 25 W, and it should go away.

[Vercomm]

I will try the suggestions and let you guys know.

[Vercomm]

I finally got this radio on the service monitor and found it was txing 29watts, so I turned it down to about 17watts to verify if that was the problem. I let it sit for a couple minutes and turned it back on to hear the same 5 second tone. I guess it is the SRAM is buggered. If anybody knows what I can do to fix and has a method of procedure it would be much appreciated.