5800 Refrigerated Sampler Service Guide - Isco

5800 Refrigerated Sampler Service Guide
Section 4 CPU and Power Supply
4.2 Test Points Test points and their values for the 5800 CPU are listed below in
Table 4-1. See the schematic diagram in Figure A-4, Appendix A,
which shows their board connections in red for easier viewing.
Table 4-1 Test Point Functions and Values
Test Point Function Value
TP10 2.5V reference voltage 2.462 to 2.538 volts (1.5% accuracy)
TP15
Home output from distributor stepper Goes low when both phases are being driven at 70.7%.
motor driver
TP5 Liquid Detect after filter This is the filtered AC signal from the liquid detector.
TP14
MCKO (Master Clock Output): This output
is enabled when in the CPU board
test mode (TEST command through the
serial port). See Section 4.3.
8 MHz signal (125 nsec period)
TP11 +VB – power to RAM About 2.7V on battery, 3.3V on AC power
2.5V minimum.
TP9 Battery current minus Should be less than 3µA. Best measured with 12V
TP8
Load current on lithium battery.
power completely disconnected. Reading may depend
on meter used.
TP7 Power Fail input to CPU Goes low when 12V power to board falls to about 8
volts.
TP6 RS232 Invalid output If a valid RS232 signal is present on any receiver input,
this output will be high.
TP4 Analog input pulses About 1200 Hz (0.8 ms period) at 10 mA input.
TP3
Ground. Return for TP4.
4-6