TM-455E Is it dead, or just unconscious? ;-)
 

Hi,

I've just purchased a second-hand TM-455E 70cms multimode to use as an
uplink transciever for AO-40. It initially powered up okay, and receive
worked well. However transmit was "interesting". When the mike-key was
released the set would continue to transmit for up to around two
seconds. The period of time was not constant, and would depend upon the
length of time the mike was keyed. This happened on both FM and USB. I
couldn't find any reason for this in the manual, so I decided to do a
full reset by holding down the MR and Power keys. The set switched off
and I've not been able to power it on since. The fuse hasn't blown,
checked that. Tried wobbling the power cable and the cable between the
main unit and front panel.

What HAVE I done???

Paul
~~~~~

I've heard of similar delays happening because of faulty electrolytic
capacitors in the mike. In this case, there was considerable remote control
circuitry in the mike, and the bad caps were causing voltages to hang around
when they shouldn't.

Try unplugging the mike and see if it will power up. If so, that may point
you to the problem area. If that doesn't help, perhaps there's a battery in
the radio that needs to be replaced, or maybe a very large "super" capacitor
needs to charge up before the microprocessor will resume normal operations.

Bob M.
======
"Paul Duncan" wrote in
message ...
Hi,

I've just purchased a second-hand TM-455E 70cms multimode to use as an
uplink transciever for AO-40. It initially powered up okay, and receive
worked well. However transmit was "interesting". When the mike-key was
released the set would continue to transmit for up to around two
seconds. The period of time was not constant, and would depend upon the
length of time the mike was keyed. This happened on both FM and USB. I
couldn't find any reason for this in the manual, so I decided to do a
full reset by holding down the MR and Power keys. The set switched off
and I've not been able to power it on since. The fuse hasn't blown,
checked that. Tried wobbling the power cable and the cable between the
main unit and front panel.

What HAVE I done???

Paul
~~~~~

I've heard of similar delays happening because of faulty electrolytic
capacitors in the mike. In this case, there was considerable remote control
circuitry in the mike, and the bad caps were causing voltages to hang around
when they shouldn't.

Try unplugging the mike and see if it will power up. If so, that may point
you to the problem area. If that doesn't help, perhaps there's a battery in
the radio that needs to be replaced, or maybe a very large "super" capacitor
needs to charge up before the microprocessor will resume normal operations.

Bob M.
======
"Paul Duncan" wrote in
message ...
Hi,

I've just purchased a second-hand TM-455E 70cms multimode to use as an
uplink transciever for AO-40. It initially powered up okay, and receive
worked well. However transmit was "interesting". When the mike-key was
released the set would continue to transmit for up to around two
seconds. The period of time was not constant, and would depend upon the
length of time the mike was keyed. This happened on both FM and USB. I
couldn't find any reason for this in the manual, so I decided to do a
full reset by holding down the MR and Power keys. The set switched off
and I've not been able to power it on since. The fuse hasn't blown,
checked that. Tried wobbling the power cable and the cable between the
main unit and front panel.

What HAVE I done???

Paul
~~~~~

Hi Bob,

Thanks for the reply.

Bob M. wrote:
I've heard of similar delays happening because of faulty electrolytic
capacitors in the mike. In this case, there was considerable remote control
circuitry in the mike, and the bad caps were causing voltages to hang around
when they shouldn't.

Try unplugging the mike and see if it will power up. If so, that may point
you to the problem area. If that doesn't help, perhaps there's a battery in
the radio that needs to be replaced, or maybe a very large "super" capacitor
needs to charge up before the microprocessor will resume normal operations.

Well, it eventually did power up, but there was also other damage.
Turned out it probably taken a knock during transport to me. Amongst
other things, three out of the four clips holding the front panel on had
died. Its gone back for repairs to be paid for by the senders carrier.
Hopefully it will be fully functional when it returns. What I should
have done was try it with the mike from my TM-V7E - I'm fairly sure
they're the same.

Ah well, thanks again!

Paul
~~~~

Hi Bob,

Thanks for the reply.

Bob M. wrote:
I've heard of similar delays happening because of faulty electrolytic
capacitors in the mike. In this case, there was considerable remote control
circuitry in the mike, and the bad caps were causing voltages to hang around
when they shouldn't.

Try unplugging the mike and see if it will power up. If so, that may point
you to the problem area. If that doesn't help, perhaps there's a battery in
the radio that needs to be replaced, or maybe a very large "super" capacitor
needs to charge up before the microprocessor will resume normal operations.

Well, it eventually did power up, but there was also other damage.
Turned out it probably taken a knock during transport to me. Amongst
other things, three out of the four clips holding the front panel on had
died. Its gone back for repairs to be paid for by the senders carrier.
Hopefully it will be fully functional when it returns. What I should
have done was try it with the mike from my TM-V7E - I'm fairly sure
they're the same.

Ah well, thanks again!

Paul
~~~~