The Advanced
®
Model 3250/4250 Service Manual
28
+5V DC 1 to reader
receive data 10 from reader
gnd/earth 9 common
Signal Pin Direction
Barcode Port Connections
A suitable barcode scanner is available from
Advanced Instruments. To interface with the
instrument, the barcode scanner must be pro-
grammed as follows, referring to the scanner
users guide.
1200 bps
CR suffix
disable beep after good decode
triggerless trigger mode (optional)
Internal Printer, Serial Suffix A - C: The
internal printer assembly (325400) consists of
the sheet metal mounting bracket, thermal print
head (FL0403), thermal printer PCB (FL0402),
and thermal printer PC board assembly
(PCB400). All of this is connected to the appli-
cation board (PCB605) via cable (M20465).
Note: The internal printer may be powered by
+5 VDC (red/orange wire) or +12 VDC
(violet wire). Consult system schematics
for proper service.
Internal Printer, Serial D and Higher: The
internal printer assembly (325420) consists of
the sheet metal mounting bracket, thermal print
head (325404), main control board (325421),
printer interface board (PCB402), and the con-
trol cable (325419). All of this is connected to
the application board (PCB605) via cable
(325415), and on some models via cable
(325033).
The printer interface board (PCB402) contains
the power circuit converting +12 VDC into +5
VDC, a feed/self-test switch (S1), and some
diagnostic LEDs. If the self-test switch is
depressed as instrument power is applied, the
printer will enter self-test mode and print out
settings and a test character set. The LEDs
indicate the operation of the paper-out detector
(D1 yellow) and the door/platen-closed detector
(D2 red). POWER CONNECTION TO J1
mands and block probe resistance. These sig-
nals are provided to the FET driver transistor
mounted on the driver board (PCB523).
The head motor is controlled by the application
board via two FETs and the PLD logic. LEDs
are provided on the application board for moni-
toring the drive signals. LEDs are also provid-
ed to monitor the signals from the head sensor
board, described below. Two active low head
up/head down signals are sent to the driver
board (PCB523) where they are converted into
acceleration, direction, and step commands for
the motor drive chip. The motor drive chip
translates these commands into current con-
trolled outputs that move the DC stepper motor
and provide idle torque when no movement is
required. The following adjustments may be
available for the motor circuit: R10 and TP16
are used to set the initial acceleration to a rise
time of 4uS. R21 and TP15 are used to set the
run frequency to 8 Khz.
The fan is controlled by a FET transistor on
the application board, that is interfaced to the
processor through the application logic.
Head Transition Board (M20450) Descrip-
tion: The stir/freeze coil and the sample probe
are connected to the head transition board
which allows easy sample probe replacement.
Head Sensor Board (3D3380) Description:
This board provides two optical sensors that
interface to a PLD on the main board. These
two sensors detect the head-up and head-down
conditions.
Keypad Transition Board (FLO520)
Description: This board provides the interface
to the keypad along with pull-up resistors for
the keypad LEDs.
Barcode Port: A D-type, 15-pin barcode port
is provided in the back of the instrument for
connecting and providing power to such a
device. For proper operation, the barcode port
requires a 1200 bps, RS-232 signal providing
asynchronous serial data containing 1 start bit,
8 data bits, 1 stop bit, and no parity.
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