6-62
If contents of 2003h not equal to 00101101, then test result
=
FAIL.
If contents of 2002h not equal to 10010110, then test result
=
FAIL.
If contents of 2001h not equal to 01001011, then test result
=
FAIL.
If contents of 2000h not equal to 10100101, then test result
=
FAIL.
Set test result
=
PASS.
If run from this level, all four tests are selected in turn, or one may execute anyone test by selecting
2361 to 2364. The contents of the first four bytes of U322 have been written and will now be tested
against the values that were thought to be written, any failure to match will cause that test to fail.
U322 is decoded by reading address 2000h.
Testing Method:
Vertical Buffer U322 (diagram 16):2360
U322
5. Verify the RO chip enable to U240 pins 1 and 15 is LO. If ok to here, replace U240.
4. Verify the outputs of U221, U212, and U210 are stable and correct after the LDCOUNT strobe to
the previous bus.
3. Verify that U323A pin 3 is LO.
2. Verify that after LDCOUNT strobe, the outputs of Address Multiplexers U222, U220, U211 are
stable and of the correct level for the test selected.
1. Run test 2350 in CONTINUOUS mode and verify the LDCOUNT strobe pulse at pin 11 of U222,
U220, and U211.
Now using the CH 2 probe:
Set up the 2430 test scope as in Step 1 of the 2110 troubleshooting procedure.
Troubleshooting Procedure:
4. Readout Buffer U240 may be defective.
3. Address Multiplexers U221, U212, and U210 may not be operating properly.
2. Flip-flop U414A may not be resetting, or U323 pin 3 might
be
HI due to a failure.
1. LDCOUNT might not be strobing the data into U220 and/or U211.
If 2 or 3 tests fail, then there is a bus problem of some sort that must be examined. If all four tests
FAIL, then the problem can be in several locations.
NOTE
00 through 03
=
0, and 04 through 011 map to DO to 07. i.e., 07
=
03. By knowing
which test FAILs and the bit pattern, one may easily determine the problem bit(s) (look for
the bit column in the failed tests that are the same).
Table 6-6 (cont)
Maintenance-2430 Service
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