Tektronix 2430 - Video Option Troubleshooting

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6. If all inputs to U530 ok, replace U530.
5. Check that pin 8 of U530 is HI and that activity is occurring on pins 10, 11, 12, 13, 15, 16, and 17.
If no activity, troubleshoot the problem.
4. Check that pin 14 of U530 is at +5 V and that pin 1 is ground. If not, troubleshoot the cause.
3. Check pins 2, 3, 4, 5, 6, 7, 8, and 9 of Data Bus Buffer U532 for activity (not stuck HI or LO)
occurring at the same time as the negative strobe on U332C pin 8. If stuck, troubleshoot the bad
bus line.
2. Check U332C pin 8 (schematic diagram 20) for the same negative strobes as at U830 pin 3. If not
present, replace U332.
NOTE
The GPIBSEL signal also selects the Video Option registers. If communication via the
GPIB interface is ok, then the select signals to Data Bus Buffer U532 (schematic
diagram 20) and the buffer itself are ok. Suspect a problem with Programmable Line
Counter U530 (schematic diagram 21).
1. Check A12U830 pin 3 (schematic diagram 1) for two negative strobes about 10.5 /J-S apart. (View-
ing scope Sec/Div at 2 /J-S , trigger on negative slope of the signal.) If not present, replace U830.
Troubleshooting Procedure:
If SET TV is pressed and an error message of "TV OPTION NOT INSTALLED OR FAULTY" is
displayed, then the power-on SELF TEST has detected a problem (assuming the Video Option is
installed). During the power-on SELF TEST, a byte is written to Line Counter A12U530 (schematic
diagram 21) and read back. If the byte read back is not what is expected, a flag is set to indicate that
the test failed. When the SET TV button is pressed, that flag is checked to see if the Video Option
checked ok at power-up. If the test was not ok, the error message is displayed and the warning bell is
sounded. If no error message is displayed, but test 2180 (FLD2) fails either at power-on or during a
subsequent SELF TEST, troubleshoot as indicated in Table 6-6 Procedure 7 "Extended Diagnostics"
for that failure.
Video Option (schematic diagram 21):VIDEO
OPTION
FAULT
Video Option Troubleshooting
Table 6-7
Maintenance-2430 Service