I have a TM-741A tribander with 50/144/450 modules installed. The unit was
inactive for several years, but was working great at the time of last
usage - no problems whatsoever.

I recently tried to put it back on the air and when I applied power and
pressed the power switch "-on-" was displayed in the center of the display
and the three band control LED's were lit red.

After that, pressing the power switch repeatedly had no effect -- the unit
would not turn off until I shut off the power supply. No other switches or
combination of switches had any effect. The only thing I can get to work is
the display test (F+MHz+Power On) after shutting off the power supply,
letting the unit sit un-powered for a while, then applying power and
pressing that key combination.

While the display test is up, if the VFO switch is pressed the display test
ends and a "0" appears in the band A area of the display. This remains
until the unit is powered down and re-powered.

If the unit is powered down while the display is "-on-" and powered up again
within a minute or so, the unit powers bacj up to the "-on-" display without
touching the power on button.

I found the two solder-in lithium batteries to be dead. One battery is for
the display unit, the other is for the control unit. I replaced both
batteries with new Kenwood part numbered batteries, which now check good
in-circuit. The symptoms described above did not change after replacing the
batteries.

I'm stumped. I was looking for some sort of physical master reset switch
on the control board, but found nothing. I tried all of the switch
combinations listed for various memory reset functions with no change in
symptoms. The service manual is of little help -- does not cover any
troubleshooting or battery replacement procedures.

Anyone have any helpful thoughts (other than sending it to Kenwood for
repair - my next step)???

Thanks
Chuck W9BIK

I had the exact same behavior with the TM-741A that I have. I was able to get the rig to start working again by simply leaving it in the "-on-" state for a while. I plugged it in and turned it on and about 12 hours later when I checked it, the radio had frequencies displayed and I was able to check in to a local 2M repeater. Chuck and I spoke offline regarding the issue and he suspects it's an internal battery that is starting to go. By leaving it on for a while it charged up enough to start working again. We are posting this info so if others run into this problem they will have an idea on how to fix it. Note, my first attempt was simply plugging in the radio but not leaving it in the "-on-" state. That did not work, it had to be "-on-"

73 Steve K8SRR