Contact problems in Module Termination Unit TU830/831
Problem:Solution
A description of this resolution:
'Contact problems in Module Termination Unit TU830/831' resolves the following:
The underlying cause is:
A description of this resolution:
- Installations whith unreliable MTU signal contact must have the TU830/831 replaced or repaired
To eliminate problems with failing MTU signal contacts, we have improved production process quality and inspection routines. All boards produced since w722 (1997, week 22) are produced and inspected according to the improved routines. There is no unambiguous way to distinguish between MTUs pro-duced before or after W722. A module with a bottom cover marked 3BSC930221R11 is produced after W722 but a module with a bottom cover marked 3BSC930221R1 could be produced either before or after W722. As an additional precaution we have also made a minor modification to the MTU’s plastic bottom cover to improve contact spring guidance. A minor adjustment has also been made to the contact spring itself, making it more tolerant to variations of the solder layer on the pad.
[ref SR7039 VASMASOITA0025 ]
'Contact problems in Module Termination Unit TU830/831' resolves the following:
- I/O Modules fail to leave Reset state
In a number of cases the following erroneous behavior of S800 I/O modules mounted in Module Termination Unit TU830/831 have been reported.
* I/O Modules fail to leave Reset state, red F(ault) LED is on, at power up or following a hot plug operation.
* Touching or bending I/O modules can cause an operational I/O module to toggle between Reset and Operational states.
The underlying cause is:
- Signal contact for acknowledging that the I/O module is locked in position
The root cause for this behavior has turned out to be the operation of the MTU´s signal contact for acknowledging that the I/O module is locked in its position. Investigation of failed MTUs shows that some TU830/831 have insufficient deposit of solder on the contact spring’s contact pad. Tests performed after applying sufficient solder on the contact pad on such MTUs have confirmed reliable operation.
- Article imported from the previous version of KnowledgeBank
Asked 12 years ago
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