Troubleshooting
PROM Chip Replacement (Software Upgrade)
65
Figure 26. Replacing PROM Chip (Keypad/Display version shown)
C5
+
Y2
U5
J1
LED1
5V
Cable to Power
Supply Board
consoles\tls50\50cpurm.eps
GND
8V
These voltage test points are on the back of
the CPU board (directly behind this upper left
corner))
1) Orient PROM so that the small indented dot on
top of the chip is on the same side with the small
triangle embossed in the socket's base; or,
2) If the chip is covered with a label you can also orient
the chip correctly if you insert the chip in the socket
with its angled corner in the same angled corner of the
socket.
3) Carefully align the chip's pins with the socket's pins.
(If you have the pins aligned correctly, the chip will seem to
drop into the socket.) Then push down firmly and evenly
on the chip until it snaps into the socket.
4) Check to see that all pins are in place and none are bent.
PROM chip
socket
STATIC SENSITIVE - WEAR
GROUNDED ANIT-STATIC
WRIST STRAP BEFORE
HANDLING THIS BOARD!
