August 25, 2014

Have you ever encounter Chip Failures of the TN55NO2 and TN55TOX Board on Huawei OSN 8800

Summary: The clock chips used on some TN55 of Huawei OSN product Optical OSN 8800 NE have design defects. As a result, the failure rate of the chips is 5% after they are in service for 2 years. In the case of a clock chip failure, services on these boards will be interrupted and cannot be restored even after you remove and reinsert or perform a cold reset on the boards.
[Problem Description]
Trigger conditions:
The chip failure rate is 5% within 2 years. The chip failure rate is proportional to the service period but is irrelevant to application scenarios.
Symptom:
On the transmission faulty board, a Hard_Bad alarm is reported and cannot be cleared and services are interrupted.
Identification method:
1. Check the bar codes of the boards against the attachment. If the bar codes are included in the attachment which provided by the official website, you can determine that the boards are at risk of a clock chip failure.
2. If the previously described symptom occurs on a TN55 board, you can determine that the board is at risk of a clock chip failure.
You can also query the register using the following commands.
[Root Cause]
The clock chip has design defects. As a result, the TN55 boards have 5% failure rate within 2 years.
[Impact and Risk]
Optical OSN 8800: On a board with a defective clock chip, a Hard_Bad alarm is reported and services are interrupted. The services cannot be restored even after you remove and reinsert or perform a cold reset on the board. The chip failure rate is 5% within 2 years and is proportional to the service period.
[Measures and Solutions]
Recovery measures
Replace the boards with a defective clock chip.
Solutions:
Replace the boards with a defective clock chip.
Material handling after replacement:
For markets outside China directly scrap the boards. For markets inside China, send the boards back to the Spare Parts Center for disposal.

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