Batboard

Have some T71 42-50 Maratracs with clamshell heads, they all seem to work ok but one gives me 3 beeps (external eeprom failure per the manual) on power up and won't TX.

All other functions appear to operate properly.
The RSS will not key the unit either.

Any suggestions?


Thanks

Andy, try going in there and make sure the eeprom is in there firmly. I have seen a few that for some reason the eeprom came loose!?? Just a suggestion, you may have already done that.

Frank

I tried reseating the eeprom, also swapped one from a "known" working unit.

No luck

You could conduct an experiment if you have a little time and an 800 Maxtrac with an HLN5172A five-pin logic board.

It appears that the HLN5402A Maratrac logic board and the HLN5172A 5 pin Maxtrac logic board are virtually identical.

The Maxtrac board might work just fine in the Maratrac. You would start by blanking the Maxtrac board, then swap in the firmware chip from your Maratrac logic board. Then use the replace logic board steps in the Maratrac RSS.

If it doesn't work, you can always put the firmware back on the Maratrac logic board and reinstall it.

Are you sure it was the EEPROM you swapped and not the EPROM?
I know in older Maxtracs they didn't use an actual EEPROM, but a Dallas chip, which is basically a battery backed up static RAM, the radios that have them are now old enough that it's not unusual for the battery in them to be dead. I believe they were soldered in, not socketed. I would guess the Maratracs used them too, so make sure you swapped the right chip (the EPROM has a glass window on top covered by a sticker, you want the chip next to it)

"...didn't use an actual EEPROM, but a Dallas chip,..."
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Good catch - that probably is his problem. When he said he had exchanged it - I skipped right past that thought - but you are right - since the EEPROM is soldered in - the socketed firmware EPROM could be what he changed.

I had one of those Dallas chips go bad in a Maxtrac logic board. I took it out and put in a socket. A 28C16 worked fine as a replacement.

OK, you guys are correct. I swapped the E-P-R-O-M.

I'll check the E-E-P-R-O-M today.

I'm down to 2 brain cells and one of them's not doing so well this week.

"...I'm down to 2 brain cells and one of them's not doing so well this week..."
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It happens to all of us! That's why we help each other here.