SCP SCIENCE
32
KeyPad
Version 1.0
FIGURE 22: A/D CIRCUIT TEST POINTS AND J9 LOCATION
Legend
1.
2. TP12 (Analog input to CPU)
3. TP13 (Differential voltage)
4. TP7 (5Vdc analog voltage)
5. TP6 (GND analog voltage)
6. TP10 (1Vdc reference voltage)
7. TP11 (RTD supply voltage)
8. TP14 (RTD signal voltage)
9. J9 header with RTD cable disconnected
(pins 1 to 5)
A/D CONVERSION BEHAVIOR
• If all the previous measurements are correct, make
sure that all the external components or
instruments (snesors, PROBE, DigiSET, etc) and
interconnection cables are properly connected.
• Reconnect cable J9 to its header and verify if the
system is heating up accordingly and the block
temperature feedback is correct.
CPU SECTION
The CPU section is basically the microcontroler
PIC18F8722, U6 (see fi gure 23 for location)
FIGURE 23: CPU AND REFERENCE VOLTAGES LOCATION
Legend
1. Pin 3 of J1
2. Pin 1 of J1
3. Via to pin 27 of U6
4. Via to pin 26 of U6
5. Via to pin 25 of U6
6. U6, CPU
If anyof the sections 1 to 5 has been verifi ed and
a CPU problem is suspecgted then try the following
sections.
LCD DISPLAY PROBLEM
If the section 1 has been fully investigated and the
system is always returning to the default setup (EN
language, default heating block type etc.), replae the
KeyPad PCB.
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