Thermo Scientific 3403 Manual page 53

Section 8
Appendices
Interface PCB
J2 – General I/O with CPU
(continued)
J2 is not a good place to measure anything. In general, most of these
signals should be checked at other access locations. Better points for
measurement are listed after a brief description.
Pin 1 – "PS15" DC voltage supplied out to key switch. Refer to J4 for
troubleshooting.
Pin 2 – "+12V" DC voltage supplied to audio transducer (AL1), 5 volt
regulator (U2), and the VFD in ULT applications. The voltage level at
"+12V" should be one diode drop down from "+DC" (CPU and Power
board). Typically, these will be ~10.5 VDC and ~11.3 VDC, respectively.
Easiest access point is J1 pin 1: can also be check at '+' side of AL1 or U2
pin 1 (toward J5 & J2).
Pin 3 – "SW-DOWN" Keypad status passed to CPU. See J3 for
troubleshooting.
Pin 4 – "SW-SELECT" Keypad status passed to CPU. See J3 for
troubleshooting.
Pin 5 – "SW-UP" Keypad status passed to CPU. See J3 for
troubleshooting.
Pin 6 – Ground
Pin 7 – "BEEPER" Signal from CPU to activate an audible alarm. +5
VDC when active, measure at the anode (+) of D1 (pin away from audio
transducer - AL1). Anode is also the side of the diode without a bar.
Pin 8 – "ALARM-EN" Output supplied to CPU indicating that the key
switch is in position 3. +5 VDC when active, measure at J4 pin 3.
Pin 9 – "BAT-EN" Output supplied to battery charging circuit. Refer to
J4 pin 2 & 3 for troubleshooting.
Pin 10 – "PS15R" Secondary side of key switch. Refer to J4 for
troubleshooting.
J3 – Switch Input from Keypad
Pressing a keypad simply shorts it to ground. For instance, pressing the
UP pad will cause pin 1 to short to pin 4. Pin 1 is toward the top of the
board or R2/D1. NOTE Pin 1 on a connector can frequently be
identified by a square pad on the PCB.
Pin 1 – "SW-UP" Input from UP keypad. Grounding this pin will
simulate the 'up' pad being pressed.
Pin 2 – "SW-SELECT" Input from Mode/Mute/Select keypad.
Grounding this pin will simulate the 'Mode/Mute/Select' pad being
pressed.
Pin 3 – "SW-DOWN" Input from DOWN keypad. Grounding this pin
will simulate the 'down' pad being pressed.
Pin 4 - Ground – common to one side of each of the keypads.
Thermo Scientific Midi 40 CO2 Incubator 8-21