There is this Epson dot matrix DFX-8500 printer which powers up for
just about 40 seconds and goes off . When I remove the magnetic (reed
switch) sensor cable the power light stays on but the Head does not
move and the pause light also stays on and does not respond to any
command from the pannel. May I know what might be the problem?

ha escrito:

There is this Epson dot matrix DFX-8500 printer which powers up for
just about 40 seconds and goes off . When I remove the magnetic (reed
switch) sensor cable the power light stays on but the Head does not
move and the pause light also stays on and does not respond to any
command from the pannel. May I know what might be the problem?

Which magnetic switch? The door switch? A print head switch? Probably
the printer is detecting a jammed motor or mechanism and that´s why it
turns off by itself.

Considering the value of that printer, you really would want to have it
repaired by Epson. Spares for it are quite expensive, and you can do
more damage to it if you don´t know what you are doing.

Or maybe the EEPROM is dead.