4-11 Model 2400 Service Manual
Troubleshooting
2400-902-01 (G - Feb 2006)
Digital circuitry checks
Digital circuit problems can be checked using Table 4-3. See “Principles of operation” for a
digital circuit description.
Table 4-3
Digital circuitry checks
Step Item/component Required condition Remarks
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
Power-on test
U3 pin 19
U3 pin 7
U3 pin 68
U3, lines A0-A19
U3, lines D0-D15
U3 pin 66
U4 pin 7
U4 pin 8
U13 pins 34-42
U13 pins 26-31
U13 pin 24
U13 pin 25
U3 pin 43
U3 pin 44
U3 pin 45
U3 pin 47
RAM OK, ROM OK.
Digital common.
+5V
Low on power-up, and 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
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 RX line.
RS-232 TX line.
IEEE-488 data bus.
IEEE-488 command lines.
IEEE-488 REN line.
IEEE-488 IFC line.
D_ADDATA
D_DATA
D_CLK
D_STB
Analog circuitry checks
Table 4-4 summarizes analog circuitry checks.
Table 4-4
Analog circuitry checks
Step Item/component Required condition (Bench defaults) Remarks
1
2
3
4
5
6*
7*
8*
9
TP200
TP201
TP202
TP203
TP213
TP218
TP219
TP214
TP232
>200V voltage protection
SOURCE +10V
SOURCE + 10V (SVMI)
SOURCE +10V
SOURCE +10V
OUTPUT COM
OUTPUT COM
SVMI, OUTPUT ON, 20V, on 20V RANGE
Bench defaults
-13 ±1V
-5V ±.5V
-10V ±1V
-10.5 ±1V
0V ±.1V
7V ±.7V
7V ±.7V
20V ±.5V
6.4V ±6V
*Measured with respect to OUTPUT COM (TP501)
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