Vcore Or Vrm Voltage Dropping Problem In Motherboard

VCore or VRM Voltage dropping problem in motherboard SAMSUNG Part No - BA41-02206A

PROBLEM - After getting Power ON the motherboard takes the load of 0.450 A in DC supply. After some time the load gets dropped to 0.137A as seen in the DC power supply.
 SAMSUNG Part No - BA41-02206A
TROUBLESHOOTING - As per the Load of 0.137 A, it can be concluded that the system is triggered and is in the S3 state (RAM Triggering State). So I checked State voltages after the S5 stage and found all supply, VCC, VDD and driver voltage ok. But found that VCORE voltage is missing.

There could be many reasons for VCORE or VRM voltage missing like:-
 * CORE IC faulty.
* CORE Requirement not complete.
* RUN section or the S0 state Voltage not transferred.
As current Load was going HIGH to LOW (From 0.450A to 0.137A). So I Checked PCH Supply of 3.3 V, it gets LOW to 0.98V when load drops to 0.137 A. While the PCH supply remains at 3.3V when the load is at 0.450 at the time of triggering.
By this symptom, I was sure that the chipset or PCH was malfunctioning that is causing the VCORE or VRM voltage to drop when the motherboard triggers to the S0 state. 
I also tried to direct switch RUN SUPPLY for testing but the switching voltage at the output remained LOW. This confirmed that it is coming LOW from CHIPSET.
Run Section Supply Switching
The above pic indicates the RUN section switch that i was trying to direct switch manually.
So, I decided to remove Chipset. After PCH or Chipset removal I checked RUN supply it became OK.
Pch removed


PCH removed from mpothewrboard as can be seen in the above pic.


I Fix reballed another SJTNV Chipset then motherboard working perfectly Ok.

 PCH Chipset  Reballing


Thanks for reading this case study. 


Mr. Vijay

Sr. member 

Laptex Family





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