6-81
1. Input the 2430 calibrator signal to the channel that is not operating properly. If neither is working,
start with CH 1. CH 1 components will be referenced, with the CH 2 Circuit numbers given in
parentheses. Set the bad channel to 100 mV/div, DC coupled, with 50 n termination off. Adjust the
screen waveform so the ground dot on the 2430 under test is 2 divisions below center screen if
possible. Set the input coupling of the other channel to ground. Turn the A SEC/DIV to 5
J.l.S.
NOTE
Channell components are reference (Channel
2
components are in parenthesis).
CCD Output Troubleshooting Procedure (Schematic Diagram 14):
The CCD output stage is a probable area for failure if a SELF CAL fails any of the 7100 or 7200 tests.
Check these tests to see which channel did not pass, then perform the following steps.
Failure of tests in 7100 or 7200:
NOTE
If any CCD or Peak Detector is changed, do not run a SELF CAL until the CCD OUTPUT
Gain has been set using the EXT CAL ADJUSTS, test pattern number 6. Adjust the
±
2
division gain for the changed channel both Side
1
and Side
2
according to the directions
given in the display.
1. Change the associated CCD/Clock Driver. If the problem is not corrected, troubleshoot the CCD
Output circuitry.
If a single channel fails:
3. If the clocks seem to be functioning normally to this point, check the shared clock signals at
TP345, R366, R465, and R466. If these points are not switching, change the CCD/Clock Drivers
(U350 and U450).
2. If the clocks are running correctly at the collectors of 0450, 0460, 0550, and 0560, check to see
if pins 2, 3, 5, 6, and 7 of R470 are switching correctly (compare pins 2, 3, 4, and 5 to waveforms
68 through 71 on diagram 10).
If
not switching correctly, check the outputs of U470 for correct
clock. If not present there, troubleshoot the Phase Clock Array (U470); if ok there, find the open.
1. Check the CCD clocks. To determine if a clock problem is internal or external to the CCD/Clock
Driver hybrid, compare the collector voltages of 0450, 0460, 0550, and 0560 to Waveform illus-
tration 67 (associated with schematic diagram 10).
If
any of the clock waveforms are different,
check the base of the associated transistor(s). If the base voltage is switching correctly, change
the defective transistor. If not switching, trace back to the clock source from U470, the Phase
Clock Array (on diagram 11), and check there. If the clocks are not correct there, change U470.
If both channels fail:
The CCDs are a good suspect if any of the 7000-series diagnostic tests failed, especially in the 7300
and 7400 subsets. The Extended Diagnostics menu should be examined to determine if the problem is
in only one or in both of the channels.
Troubleshooting Procedure:
Failure of Tests in 7300 and 7400:
Table 6-6 (cont)
Maintenance-2430 Service
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