Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail


Hello again: The continuing saga ... (see my pervious posts re CTT and vet nonlin)

1/ New U400 channel switch 155-0236-00 has fixed the CH1, 2 nonlinearity.
2/ Chuck mentioned that the CTT test fails and TEST 05 FAIL 42 may be due to the U500 trigger hybrid 155-0239-xx, that some may work otherwise but fail in a CTT scope.
I have two spares off epay, but exchanging for the original U500 gave no change. Perhaps the epay units also have the same fault?
3/ Today I tested my working 2465B CTT and 2467B CTT and both pass all tests and accurately measure the 10.000 output of a Leo Bodnar GPS.
I have now exchanged the working units U500 trigger hybrids into the fault unit, but again no change, all faults still present.
4/ The option board has an EEPROM, could that be the culprit? I have also exchanged it with a working unit and same result.

IF I remove the options board and place the 4 jumpers on A1 board, the self-tests without any options pass fine.

Any ideas for next steps are appreciated.

All the Best,


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