I have a trouble with my old TM-2550A.
When I turn it on, the unit does not show the display, only the red TX
light turn on without pressing any button, even PTT.
I tried to reset the CPU shorting the two pins located on the lower
board. Also, I measured the CPU battery backup, showing 3,2 V aprox.
(after 15 years?).
Then, I test the pwr and has no output (0 W).
Any ideas, and an schematic diagram would be well appreciated.
Claudio - LU3CFA

On 4 Sep 2003 10:58:20 -0700, (Claudio Adra) wrote:

I have a trouble with my old TM-2550A.
When I turn it on, the unit does not show the display, only the red TX
light turn on without pressing any button, even PTT.
I tried to reset the CPU shorting the two pins located on the lower
board. Also, I measured the CPU battery backup, showing 3,2 V aprox.
(after 15 years?).

I have the TM-2530A, lower wattage of the same radio. Had the same
problem with mine - it turned out to be the connectors between the
'head' (front panel) and the main board. With the CPU facing up, the
wires are on the far right side of the board. Clean the connections
and pins, you should be fine.

On 4 Sep 2003 10:58:20 -0700, (Claudio Adra) wrote:

I have a trouble with my old TM-2550A.
When I turn it on, the unit does not show the display, only the red TX
light turn on without pressing any button, even PTT.
I tried to reset the CPU shorting the two pins located on the lower
board. Also, I measured the CPU battery backup, showing 3,2 V aprox.
(after 15 years?).

I have the TM-2530A, lower wattage of the same radio. Had the same
problem with mine - it turned out to be the connectors between the
'head' (front panel) and the main board. With the CPU facing up, the
wires are on the far right side of the board. Clean the connections
and pins, you should be fine.

Arnold DeRoy wrote in message . ..
On 4 Sep 2003 10:58:20 -0700, (Claudio Adra) wrote:

I have a trouble with my old TM-2550A.
When I turn it on, the unit does not show the display, only the red TX
light turn on without pressing any button, even PTT.
I tried to reset the CPU shorting the two pins located on the lower
board. Also, I measured the CPU battery backup, showing 3,2 V aprox.
(after 15 years?).

I have the TM-2530A, lower wattage of the same radio. Had the same
problem with mine - it turned out to be the connectors between the
'head' (front panel) and the main board. With the CPU facing up, the
wires are on the far right side of the board. Clean the connections
and pins, you should be fine.

Ok Arnold, your answer solve the problem. I believe the connector
wasn´t the problem. I found a contact connection between the chassis
and the board you said. It is a copper pad rounding the screw hole
that connects to ground through chassis. When I touch near it, the rig
starts to operate normally.

Thank you my friend. Claudio

Arnold DeRoy wrote in message . ..
On 4 Sep 2003 10:58:20 -0700, (Claudio Adra) wrote:

I have a trouble with my old TM-2550A.
When I turn it on, the unit does not show the display, only the red TX
light turn on without pressing any button, even PTT.
I tried to reset the CPU shorting the two pins located on the lower
board. Also, I measured the CPU battery backup, showing 3,2 V aprox.
(after 15 years?).

I have the TM-2530A, lower wattage of the same radio. Had the same
problem with mine - it turned out to be the connectors between the
'head' (front panel) and the main board. With the CPU facing up, the
wires are on the far right side of the board. Clean the connections
and pins, you should be fine.

Ok Arnold, your answer solve the problem. I believe the connector
wasn´t the problem. I found a contact connection between the chassis
and the board you said. It is a copper pad rounding the screw hole
that connects to ground through chassis. When I touch near it, the rig
starts to operate normally.

Thank you my friend. Claudio