Simplex 4020 Troubleshooting Manual page 29

Troubleshooting Procedures,
If there is no 36V Mapnet
output and no A-tap voltage
Verifying Standard Slave
Processor Operation
Standard Slave
microprocessor Initialization
Continued
No 36V Mapnet output indicates the Standard Slave is not completing the power
initialization procedure. It could be unable to access the A/D converter on the
Power I/O Interface, or the microprocessor itself may have failed.
Perform the following checks:
• Check the cable from the Power I/O Interface for 36 volts.
• Check that the ribbon cable between the Standard Slave and Power I/O
Interface board is properly connected. It is easy to install this cable one
position or one row off.
• If the cable appears to be properly connected, check the following:
• Check the fuse on the 565-256 Power I/O Interface PCB assembly
• Check for overheating of the 10 watt R139 battery load resistor
(located near the right-hand side of the 565-256 Power I/O Interface
PCB assembly – see Figure 2-5, page 2-10)
If R139 is hot, the Power I/O Interface board is probably bad.
• Verify that the Standard Slave processor is running (see 'Verifying
Standard Slave Processor Operation', below)
A simple test can indicate whether or not the Standard Slave processor is
running.
Changing the SW1, switch 1 position should cause the Standard Slave
microprocessor to blink the trouble LED on and off. (see Figure 2-4, page 2-8
for the location of SW1)
Note: Be sure to reposition SW1, switch 1 back to the normal "ON"
position after this test.
Table 5-1 (page 5-1) shows what the Standard Slave checks on power up
initialization. Most supervisory readings that the Standard Slave microprocessor
makes during initialization are conveyed via the short cable connected to the
Power I/O Interface Assembly.
The Power Supply ribbon cable that is connected to the Power I/O Interface
assembly provides additional supervisory and control signals.
4-6