Tektronix 2440, User Manual

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Maintenance— 2440 Service
Table 6 -6 (cont)
3. Check U221 pins 1 and 2 for activity (ACD line is the data input). If ACD missing, troubleshoot the
signal path to and gating on the inputs of DAC Multiplexer Select register U272 (diagram 5).
4. Check U221 pin 13 for activity; replace U221 if inactive.
5. If checks good to this point and the test still fails, replace U 511.
2530 Acquisition Control Register A10U530 (schematic diagram 5):
PEAK
DETECTOR Testing Method:
For this test, the M SB of A10U530 (pin 13) will be compared with what the M SB should be with each
shift of the register. If one of the bits differs from the loaded-in pattern, the test fails.
Troubleshooting Procedure;
Set up the test scope as in Step 1 of the 2110 troubleshooting procedure.
N O T E
F o r th e fo llo w in g , s e t th e T rig g e r P o s itio n o f th e te s t s c o p e to 3 /4 . i f u sin g a n a n a lo g s c o p e
fo r te s tin g , u s e th e a p p ro p ria te h o ld o ff a n d trig g e r le v e l to v ie w th e s ig n a ls o f in te re s t.
Run test 2530 in CONTINUOUS mode. Using the CH 2 probe:
1. Check U530 pin 9 for a HI level. If LO, then check R531 and source of + 5 V.
2. Check U530 pin 8 for activity (PD SR CLK signal line); if inactive, repair.
3. Check U530 pins 1 and 2 for activity (ACD line is the data input). Repair if inactive.
4. If all inputs are good, replace U530.
2540 Acquisition Control Register A10U270 (schematic diagram 5):
GATE ARRAY
Testing Method:
For this test, the M SB of U270 (pin 13) will be compared with what the M SB should be with each shift
of the register. If one of the bits differs from the loaded-in pattern, the test fails.
Troubleshooting Procedure:
Set up the test scope as in Step 1 of the 2100 troubleshooting procedure.
N O T E
F o r th e fo llo w in g , s e t th e T rig g e r P o s itio n o f th e te s t 2 4 3 0 A to 3 /4 . I f u sin g a n a n a lo g s c o p e fo r
te s tin g , u s e th e a p p ro p ria te h o ld o ff a n d trig g e r le v e l to v ie w th e s ig n a ls o f in te re s t.
Run test 2540 in CONTINUOUS mode. Using the CH 2 probe:
1. Check U270 pin 9 for a HI level. If not + 5 V, check R269 and source of the + 5 V.
2. Check U270 pin 8 for activity (GA SR CLK signal line); if inactive, repair.
3. Check U270 pins 1 and 2 for activity (ACD line is the data input). Repair if inactive.
4. If all inputs are good, replace U270.
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