#10314 HIGH Not Tri: XO-1.5 won't boot

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#10314: XO-1.5 won't boot
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           Reporter:  wad       |       Owner:  wad        
               Type:  defect    |      Status:  assigned   
           Priority:  high      |   Milestone:  Not Triaged
          Component:  hardware  |     Version:  1.5-C2     
         Resolution:            |    Keywords:  XO-1.5 boot
        Next_action:  diagnose  |    Verified:  0          
Deployment_affected:            |   Blockedby:             
           Blocking:            |  
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Comment(by Gary Chiang):

 After further investigation on SHC00500908,
 I found out that "HDSTB1N" pin maybe soldering crack on VX855 side(the
 HDSTB1N should connect between CPU and VX855),
 Please find attached file, the "HDSTB1N_Normal.PNG" is measured on normal
 board,
 You can see the negative-edge level only reach to 400mV,
 In the "HDSTB1N_fail.PNG" (measure on SHC00500908 ) the negative level
 will reach to almost 0V,
 Due to this pin have internal pull-up resister 55 ohm on both CPU and
 VX855 side ,
 Base on this waveform, it can tell you one of the pull-up resister are
 some how disconnected.
 I guess the soldering crack happened on VX855 side, due to the CPU will
 fetch code in the first place,
 If CPU side is soldering crack , I should never have chance to measure
 this waveform.
 Will pass this board to VIA tomorrow, VIA can help us double confirm the
 root cause.
 I am still analysis the SHC005007AB, will update if I found anything.

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Ticket URL: <http://dev.laptop.org/ticket/10314#comment:12>
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