I have had a Kenwood TM-G707A mobile amateur radio mounted in my vehicle for 20 years. The radio is mounted under the seat, with the detachable front plate mounted on top of the dashboard. It has operated flawlessly until this week. This week I had to disconnect the negative battery terminal on the vehicle to do some work unrelated to the TM-G707A. When I completed the work, I reattached the negative battery terminal. When I turned on the TM-G707A and it powered up, it was in "All Lock" mode--which has never happened since I have owned the radio. According the owner's manual, pressing the "mHz" button while powering up the radio will take the radio out of "full lock" into "transceiver lock", then pressing the "F" button then the "mHz" button will unlock the radio. However, despite many repeated attempts, the radio will not exit "All Lock" mode. I have cleaned contacts on the faceplate, etc. to no avail. None of the radio wiring has been disturbed. The only modification to the radio was the MARS mod, which was done at the time that I purchased the radio 20 years ago. My only conclusions are either that a) the radio just coincidentally decided to fail when the power was disconnected to the vehicle, or b) the MARS mod somehow affected the key sequence required to unlock the radio from "All Lock" mode. Since I have never locked this radio in 20 years, I suppose that "b" could have happened. The radio appears to be fine, except for being in "All Lock" mode. I would appreciate hearing from any TM-G707A owners who have experienced something similar over the years. Thank you in advance.
Kenwood: Problems with Kenwood TM-G707A
- Thread starter railguy5
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- kenwood tm-g707a
N6JPA
A Ham Radio Operator With too much frequency.
Twenty years old radios will have component failures. There may have been a short or power surge when you reconnected the power source. I'm thinking this is an IC failure. You could check the IC's to find the fault yourself or maybe send it in to Kenwood for repair. It would be more cheaper to buy a new radio then repair it. It is also possible that component that failed is no longer available.
MTS2000des
5B2_BEE00 Czar
So here is what you may be facing: EEPROM failure. These radios, like most modern radios, rely on a small EEPROM to save data like memory channels, save state data (such as what the radio was doing when last powered off), etc. My guess is, that EEPROM has failed and for whatever reason, it is in a save state of "lock" and won't "come out of it". If a hard reset won't wake it up, you could try getting ahold of a PC cable and download the free software from Kenwood and see if you can recover it that way, but my guess is, an EEPROM replacement is the only option. 20 years of writing save state is about right, they die like this.
MTS2000des
5B2_BEE00 Czar
Service manual here:
EEPROM is IC511, but type/size isn't listed, so you'll have to hit up Kenwood parts to see if it's available.
EEPROM is IC511, but type/size isn't listed, so you'll have to hit up Kenwood parts to see if it's available.
Thank you to those who replied. I did a partial reset from radio itself as described in the Service Manual, and that brought it back to life! My suspicion is that the radio was disconnected from a power source for long enough (the vehicle battery was disconnected for 2 days) that it lost some memory off of the main circuit board. The memory channels appear to be intact and I reprogrammed a few settings from the radio face successfully. So, it appears that the ol' TM-G707A will live on, at least for now. I'm glad for that--I really like it, old as it is, and I am, frankly, unimpressed by many of the newer dual-band amateur mobile radio offerings.
This is exactly why I'm getting a Kenwood 641 worked on between a friend of mine and myself. I've got some newer radios and frankly, as soon as my 641 is back in action, several are going on the auction block. Great you got your 707 going!
N6JPA
A Ham Radio Operator With too much frequency.
I'm glad it worked out. Kenwood builds fine electronic products. I had a 2 meter rig I bought in the 80's that lasted until 2005.
MTS2000des
5B2_BEE00 Czar
That's just it: these radios don't "lose" memories, they are saved in EEPROM when the radio is powered down. As these EEPROM chips wear out, erratic data is one of the signs and symptoms of failing chip. It's a documented problem not specific to any manufacturer. Earlier radios used volatile memory to "save state" and thus, when the coin cell battery died, so did the save state data. This is also a problem on commercial radios and many owners of 20 year old Motorola radios are experiencing the same thing.
Nothing lasts forever and if this starts happening, it' a sign to either replace the chip (if possible) or replace the device. While EEPROMs and flash memory can withstand many many write cycles, they do wear out. After 20+ years of daily operation and "save state" writes, it's bound to show itself.
FKimble
Member
Having worked in the computer field for nearly 40 years, it seems there are 2 times when a device is most likely to fail! During an electrical storm(lightning strike) or at power on.
Frank
Frank
