Memotech Limited MTX 500, Service Manual

Page: 27 / 78

23
The under side of the MTX reveals a single screw
which secures the MTX mother board to the bottom
chassis. By removing the main screw and earth strap
the MTX Mother Board and Rear Plug panel will
slide from the case bottom.
Faults are rarely complained about but nonetheless
faults, include I/O ports that are insecurely soldered
or not 'flush' with the main P.C.B. i.e. Power Supply
socket, Printer port, cassette ear and mic and joy
stick ports.
Any competent initial check of a returned MTX should
include these ports. It should also include checking
for the nylon washers on the solder side of the board
(esp under the tip 2955 power transistor and the
joystick port sockets ) which stops RE/CPM shorting to
earth - see Page 48 of assembly instructions of Power
Transistor.
Also check power supply voltage....ideally about 22.5v
to 24.5v and check to see that c56 and c51 - 4700 uf
16v capacitors are secure.
MTX Service Manual