New Contributor
Frequent ContributorHi Fairy Tang,
To understand more about your failure, can you help to provide;
1. What is the failure symptom? Please elaborate the failure symptom in detail.
2. When did the failure happen? How did you discover the failure?
3. How did you determine the failure? Please elaborate the procedures.
4. Does the failure unit ever working before failure?
5. Did you swap the failure device to a known good board? Is the failure following the device or board?
Thank you!
Regards,
Wani
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Frequent ContributorDear Fairy Tang,
Do you have any update to the request?
Wani
Frequent ContributorDear Fairy Tang,
Please do let us know if you have any update on previous request?
Wani
New ContributorHi Wani,
Sorry for response later. I'm stuck by other hot issues in the past 2 months.
Yes, I still need your help to process this FA.
How could I do that?
Thanks so much for your patience!
Best Regards!
Fairy
New ContributorHi Wani,
I have pasted the answers you asked before.
Could you help process further? Thanks.
1.What is the failure symptom? Please elaborate the failure symptom in detail.
Unit is unable to boot and producing the following life sign: all LEDs (white and network port) are repeatedly flashing for 4 times then go off.
2. When did the failure happen? How did you discover the failure?
Failed in the field, end customer complained;
3. How did you determine the failure? Please elaborate the procedures.
3.1. Hardware Monitor reported that the "Power Good" signal was not received from one of the PMUs
3.2. Measuring impedance on U46 PMU outputs highlighted that 1V2 was shorted to GND.
The short has been isolated further to the components consuming 1V2 by removing L29.
3.3 Visual inspection of the Main Board's bottom side revealed damaged components.
D178, D180, D181 ESD protection diodes found to be damaged and these components are part of the HDMI RX 1 circuit.
3.4. Removing U216 Re-timer ASIC of HDMI RX 1(15-103032-01) terminated the short on the 1V2 power line.
However, replacing those component did not solve the boot issue.
3.5. 1V8_FPGA was also found to be shorted to GND which is produced by the other PMU, U47.
Measuring around the HDMI RX 1 circuit highlighted that CON_HDMI_IN_CEC is shorted to GND.
This short was root caused to Q104 (20-0207-02), but replacing Q104 did not fix the 1V8_FPGA short.
3.6. CON_HDMI_IN_CEC signal chain is directly connected to U197 FPGA via Q104.
Replacing U197 FPGA (16-101088-01) terminated the short on 1V8_FPGA. Unit can fully boot up now.
4. Does the failure unit ever working before failure?
Yes, this unit worked fine in the field more than a year before it failed;
5. Did you swap the failure device to a known good board? Is the failure following the device or board?
No, since it is BGA type, don’t have BGA socket board at RCFA; but has swap the failure board, it follows the board.
Thanks so much for your patience!
Best Regards!
Fairy
