Digital Circuitry Checks; Table 4-3 Digital Circuitry Checks - Keithley 2520 Service Manual

Model 2520 Pulsed Laser Diode Test System Service Manual

Digital circuitry checks

Digital circuit problems can be checked out using
on page 4-4
Table 4-3
Digital circuitry checks
Item/
Step component
1 Power-on test
2 Clip W2
3 U15 pin 7
4 U15 pin 68
5 U15, A0-A18
6 U15, D0-D15
7 U15 pin 66
8 U20 pin 7
9 U20 pin 8
10 U5 pins 34-42
11 U5 pins 26-31
12 U5 pin 24
13 U5 pin 25
14 U15 pin 43
15 U15 pin 44
16 U15 pin 45
17 U15 pin 47
for a digital circuit description.
Required condition
RAM OK, ROM OK.
Digital common.
+5V
Low on power-up, then goes high.
Check for stuck bits.
Check for stuck bits.
16.78MHz.
Pulse train during RS-232 I/O.
Pulse train during RS-232 I/O.
Pulse train during IEEE-488 I/O.
Pulses during IEEE-488 I/O.
Low with remote enabled.
Low during interface clear.
Pulse train.
Pulse train.
Pulse train.
Pulse train.
Troubleshooting
Table 4-3. See "Principles of operation"
Remarks
Verify that RAM and ROM are functional.
All signals referenced to digital common.
Digital logic supply.
MPU RESET line.
MPU address bus.
MPU data bus.
MPU clock.
RS-232 TX line.
RS-232 RX line.
IEEE-488 data bus.
IEEE-488 command lines.
IEEE-488 REN line.
IEEE-488 IFC line.
D_RETURN_DATA
D_SPI_DATA
D_SPI_CLK
D_SPI_STB
4-15