#177 [Docs] Common hardware faults and suggested fixes

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opened 3 years ago by swiftgeek · 3 comments

TPS51221 (instructions for X200 Mocha-1):

  • Isolate TPS51221 in case upper mosfet shorts:
    • To do that cut jumper-resistors:
      • 5V: R72, R52, R46, R592, R570, R569
      • 3v3: R511, R508
  • Check VREG3 - 3v3 10mA, should be always on (use C134 as testpoint)
  • Check VREF2 - 2V 100µA (near cpu, VREF2)
  • Check VREG5 - 5V, 100mA (VL5)

TODO: Describe methods of cutting traces, document wistron jumper-resistors

Rinkan contains 3v3 LDO, which might not be obvious from schematics (VCC3SW)

Rinkan depends on R72 jumper being closed

TPS51221 (instructions for X200 Mocha-1): * Isolate TPS51221 in case upper mosfet shorts: * To do that cut jumper-resistors: * 5V: R72, R52, R46, R592, R570, R569 * 3v3: R511, R508 * Check VREG3 - 3v3 10mA, should be always on (use C134 as testpoint) * Check VREF2 - 2V 100µA (near cpu, VREF2) * Check VREG5 - 5V, 100mA (VL5) TODO: Describe methods of cutting traces, document wistron jumper-resistors Rinkan contains 3v3 LDO, which might not be obvious from schematics (VCC3SW) Rinkan depends on R72 jumper being closed
Swift Geek commented 2 years ago
Collaborator

Battery charges but doesn't work from battery (x200):

  • check fuse and mosfet that connects battery to VINT20
Battery charges but doesn't work from battery (x200): * check fuse and mosfet that connects battery to VINT20
Swift Geek commented 2 years ago
Collaborator

Diagnosing broken heatpipe: https://www.youtube.com/watch?v=snjaEVWHl4M

But start with lower airflow

Note that some flaws are slowly progressing with time, but this should definitely allow you to compare performance between units of given heatsink+heatpipe+heatspreader assembly

Diagnosing broken heatpipe: https://www.youtube.com/watch?v=snjaEVWHl4M But start with lower airflow Note that some flaws are slowly progressing with time, but this should definitely allow you to compare performance between units of given heatsink+heatpipe+heatspreader assembly
Swift Geek commented 4 months ago
Collaborator

ThinkPad PMIC IC - Rinkan/Tsurumai/Kozak/ThinkEngine(PMIC part only)/etc -SHDN signal troubleshooting

  • -SHDN is latched in from both inside of the PMIC and outside signal (like thermal sensor)
  • -SHDN when pulled down by PMIC is held until either power is removed OR -RESET is toggled
  • -SHDN is pulled up to VCC3SW - LDO output of PMIC
  • When -SHDN is low (and registered by PMIC) all outputs are disabled besides VCC3SW (LDO output of PMIC)
  • -SHDN is pulled low by PMIC on its own when rail falls out of the regulation (undervoltage)

Determining which rail causes overvoltage

  • [WIP]: using oscilloscope use -SHDN as signal and see state of each rail before -SHDN is pulled low.

Fuses on PMIC controlled/monitored rails:

  • When fuse blows like on circuit that connects Vint to rail for backlight with a mosfet, monitored voltage of VBL20/VBL16 will show clear undervoltage when rail is enabled, leading to -SHDN being pulled low. This is why fuses should be checked first and if circuit is to be bypassed, similar existing voltage has to be connected to pin that monitors the rail (or code of coreboot needs to be adjusted so rail is NOT enabled)
  • Pictures of motherboards with fuses (Sicherungen) marked on them can be found on thinkwiki.de

Bypassing transient overcurrent/undervoltage while powering on that is enough to trip PMIC protection (for testing purposes ONLY):

  • Pull /RESET pin for the short time of boot process, then release. Make sure that there are no shorts on rails before attempting this workaround! Bad idea after all, blown fuse is the most likely culprit when the are no shorts but PMIC suddenly kills power with -SHDN
ThinkPad PMIC IC - Rinkan/Tsurumai/Kozak/ThinkEngine(PMIC part only)/etc `-SHDN` signal troubleshooting * `-SHDN` is latched in from both inside of the PMIC and outside signal (like thermal sensor) * `-SHDN` when pulled down by PMIC is held until either power is removed OR `-RESET` is toggled * `-SHDN` is pulled up to `VCC3SW` - LDO output of PMIC * When `-SHDN` is low (and registered by PMIC) all outputs are disabled besides `VCC3SW` (LDO output of PMIC) * `-SHDN` is pulled low by PMIC on its own when rail falls out of the regulation (undervoltage) Determining which rail causes overvoltage * [WIP]: using oscilloscope use `-SHDN` as signal and see state of each rail before `-SHDN` is pulled low. Fuses on PMIC controlled/monitored rails: * When fuse blows like on circuit that connects Vint to rail for backlight with a mosfet, monitored voltage of `VBL20`/`VBL16` will show clear undervoltage when rail is enabled, leading to `-SHDN` being pulled low. This is why fuses should be checked first and if circuit is to be bypassed, similar existing voltage has to be connected to pin that monitors the rail (or code of coreboot needs to be adjusted so rail is NOT enabled) * Pictures of motherboards with fuses (Sicherungen) marked on them can be found on [thinkwiki.de](https://thinkwiki.de/Technische_Skizzen,_Schaltpl%C3%A4ne_und_Bilder) <s>Bypassing transient overcurrent/undervoltage while powering on that is enough to trip PMIC protection (for testing purposes ONLY):</s> * <s>Pull `/RESET` pin for the short time of boot process, then release. Make sure that there are no shorts on rails before attempting this workaround!</s> **Bad idea after all, blown fuse is the most likely culprit when the are no shorts but PMIC suddenly kills power with `-SHDN`**
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