"Seventh Prince" wrote in
oups.com:

Hi,

Am doing a repair job on a Point of Sale (POS) terminal which has the
problem of the motherboard's printer socket of failing to recognise the
existance of the printer (the receipt printer is connected to the
terminal's motherboard via a connector).

Was told to change the NPN Darlington transistors (2pairs): one pair is
controlling the slip printer and the other pair is for the roll
printer. The transistors used are Sanken Electronics's SL4031. Some
other boards use Fujitsu Microelectronics's FT5754M. For this
particular board, the original transistors are Sanken's but I am using
the Fujitsus.

After soldering them and powering on the terminal, the printer can be
switched on (it is powered on via the connector thru the motherboard
printer socket). The terminal can be powered on but there's no display:
just a lit-on screen.

Burning smell is present from the motherboard. The terminal still could
not detect the slip printer. Error message is "Printer not installed".
One motherboard LED indicator is not lit and the LED for the printer
sockets is flashing.

Any advise is welcome. Thanks.


ahhhm, new motherboard & printer?

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