ASUS P8Z68-V Motherboard Electronics Help

Discussion in 'General Electronics Chat' started by kevindd992002, Oct 31, 2011.

  1. kevindd992002

    Thread Starter Member

    Nov 23, 2010
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    I accidentally connected the 3-pin connector of my Storm Force 200 to the CHA_FAN2 header of my motherboard even though the header has some sort of connection mechanism to avoid this. Apparently, with a little bit of force you could connect it the wrong way. This is what happened:

    Mobo header Fan connector
    GND output terminal ---> (nothing, hanging)
    VDD output terminal ---> minus inputterminal
    RPM input terminal ---> plus input terminal
    (nothing, hanging) ---> RPM output terminal

    If you can imagine it properly, the fan connector moved one pin down that's why it made this connection.

    Upon booting up the PC, the fan didn't work (as expected) and I waited it to boot to Windows and immediately shut it down, popped up the case open and I noticed this wrong connection and the fan wires were hot. With that, I suspect that excessive current went through the wire, to the fan, and ultimately back to the mobo. I also smelled a burning smell. I tried connecting the fan the right way and surprisingly it worked. So what damaged did the hot wire do to my fan and if ever to any other component of the motherboard?

    The only thing that is not working right now is the voltage control of CHA_FAN2 and CHA_FAN1. The CHA_FAN1 header was also damaged. Before this incident, the voltage control worked properly both in the UEFI and in Windows using ASUS AI Suite II. Now it seems that the two chassis headers only provide full +12V to the fans connected to it.

    Are fan headers isolated from each other in such a way that if one is damaged by things like this accidental connection the others won't be damaged?

    Also, can anyone explain why that connection caused this damage to this system? I spent hours thinking why it happened but can't find the answer. I mean the VDD and GND of the motherboard header weren't even shorted.

    Can this potentially affect the PSU in any way? Because my computer is still working properly, just the two chassis fan headers are problematic.

    Thanks for your help [​IMG]
     
  2. kevindd992002

    Thread Starter Member

    Nov 23, 2010
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    BUMP! Anybody can help me? :(
     
  3. R!f@@

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    Apr 2, 2009
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    Looks like my kinda stuff....
    But.....I work with pictures dude.
     
  4. kevindd992002

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    Nov 23, 2010
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    Do you mean you need a picture of my motherboard? Or schematic diagrams?
     
  5. R!f@@

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    Apr 2, 2009
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    Mobo pics. Specially around the Fan header area.
     
  6. kevindd992002

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    Nov 23, 2010
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    Ok, I'll take pics later when I get home and post them here.
     
  7. kevindd992002

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    Nov 23, 2010
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    I tried inspecting my motherboard and I really can't find any component that seems to be suspicious (burnt). Which part of the motherboard should I take a pic of specifically? Only the area where the fan headers are?
     
  8. studiot

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    Nov 9, 2007
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    Are you quite sure that the fault lies in the fan drive circuitry? Perhaps the fans are simply being driven full belt because a temperature sensor was cooked when you ran the board for too long without cooling.

    Does the BIOS and temperature monitoring software report sensible values?
    Does these change if you drive something hard or manually slow the fan?
     
  9. kevindd992002

    Thread Starter Member

    Nov 23, 2010
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    Yes, I'm definitely sure it's in the fan drive circuitry since I've tried all my fans in the CPU_FAN header and they all voltage throttle well according to my liking. The only temp sensor I need for this purpose is the CPU temp sensor and it works properly. It doesn't have any problems for fans connected to the CPU_FAN header (even the ones that were connected to the problematic header). And the board was not "ran for too long without cooling". My case has superb cooling and the side fan (the one that made all this mess) is just an optional fan.

    Yes the BIOS and temperature monitoring software report sensible values. Again, I can specify at what speed I want the fans to work. Yes, they do change when the CPU is under load and when it is idle and the fans connected to the CPU_FAN header adjust speed (voltage) accordingly.
     
  10. R!f@@

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    Apr 2, 2009
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    No pics, no glory. kekeke..

    Sorry bud. I need to see what I am trying to fix. No body here can give you much help than me I guess since I am the only one active in Mobo repairing as a full time job.

    Every one can give pointers but I can show u what to look for if I can only see it.

    One pic of complete board and close up of the fan header areas. Need to know where the control transistor or FET is
     
  11. kevindd992002

    Thread Starter Member

    Nov 23, 2010
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    As promised, pics:

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    I think I know the problem. I used a Fluke DMM to check continuity between the pins of most voltage regulators. The three pins of the voltage regulator (although only the two outmost pins are soldered onto the board) near the "USB 3.0" sign in the last picture are all shorted. This probably is the cause of the voltage regulation of CHA_FAN1 and CHA_FAN2 headers not working.

    Take note that the stupidity I did was when connecting the side fan to the CHA_FAN2 header. But the CHA_FAN2 header is connected to CHA_FAN1 header and they vary voltage together through BIOS of software. I guess the shorted voltage regulator here was the main voltage regulator IC for the Chassis Fan headers.

    Is my assumption correct?

    Also, are there possibly any other components affected by this?
     
  12. R!f@@

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    Apr 2, 2009
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    Nice board.

    I presume all fan headers are 4 pin type.

    And can u show me the fan with it's connector
     
  13. kevindd992002

    Thread Starter Member

    Nov 23, 2010
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    No. The CHA_FAN1 is a 4pin header but the 4th pin actually doesn't have any signal coming out, stupid ASUS. The CHA_FAN2 is a 3pin header. These two headers are controlled by voltage.

    The CPU_FAN and the CPU_FAN_OPT are the 4pin headers that have their 4th pin outputting real PWM signal though. These two headers are controlled by a PWM signal.

    I returned the camera to my sister for now and she's sleeping already (1:46 AM) in our place. I could vouch that the fan with its connector is damage-free though. I don't understand what could've caused the wire of the fan to heat up and not destroy it? The fan is still working properly and it reaches its rated speed of 1000RPM.
     
  14. R!f@@

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    Apr 2, 2009
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    I don't think Asus is stupid...

    U see the 4 header fan controller is somewhat tricky. The Asus probe can control fan trough windows too u know.

    The header is designed in such a way that standard voltage controlled 3 pin fans cam be used if the if the 4 pin type is not available.

    The 4 pin has PWM, tacho and Vcc. Thru bios u can set how to control the fan. Like DC control for 2 pin or 3 pin fans. PWM for 4 pin fans. It is designed to minimize the audible noise generated by the CPU fans.

    The fans and bios setting works together. So to know what ur problem is, you have to show the bios hard ware setting and also what type of chassis fan is in use.
     
  15. kevindd992002

    Thread Starter Member

    Nov 23, 2010
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    You should read about my board in www.overclock.net to believe me in saying that ASUS is stupid in making the CHA_FAN1 4-pin header. It is useless since it doesn't output any signal in the 4th pin even when 4-pin PWM fans are connected to it. Take note ONLY the 4-pin CHA_FAN1 header has this behavior. It is some kind of a "reserved" pin for THAT specific header. People even used oscilloscopes to check if there's really an output there.

    The CPU_FAN and CPU_FAN_OPT PWM headers are entirely different because they truly provide PWM signal.

    I understand you 100% about 3-pin fans being backward compatible with 4-pin headers, that is basic knowledge with fan header motherboards. But every motherboard is different and I'm telling you about my motherboard now. Before I bought this and even while having it now, I do now about its whole characteristics.

    I think the problem regarding how the header is broken is already solved. I just simply want to know if there are components that were affected by this? Simply that. I'm not hoping on reviving the fan header because I will RMA this motherboard this week or next week.

    I also know that ASUS Probe and even ASUS Suite II can control fans. Even the BIOS, and in my case it is UEFI (the new version of BIOS) mainly control the fans.
     
  16. R!f@@

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    Apr 2, 2009
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    Then they might have done it deliberately....
     
  17. kevindd992002

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    Nov 23, 2010
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    Exactly. I just want to call them stupid, lol.

    So do you've any idea with my question?
     
  18. R!f@@

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    Apr 2, 2009
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    Pics are not that clear
    The area around the headers.....Can you trace the tracks, find where they lead to.

    Need to find a regulator of sort that could have shorted.
     
  19. kevindd992002

    Thread Starter Member

    Nov 23, 2010
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    As I've said in my previous post, the regulator right beside the CHA_FAN1 header has its three pins shorted out. Could that be the only one? If so, which components could've been affected? Why was my fan not destroyed if its wires became hot when the incident happened? I also smelled something burning but not sure when it came from.

    Is it possible that the only component that was damaged was the header regulator itself? Could the PSU, Video Card, and CPU have been affected?
     
  20. R!f@@

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    Apr 2, 2009
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    What's the no. or marking on the shorted one.
     
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