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Old 11-04-2021, 05:39 AM   #21
mon2
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Default Re: 820-00244 PP5V_S0 shorted to ground

On a low voltage rail, low resistance like 60 ohms is ok.

So you are noting that L4010 had a short to ground -> you removed L4010 and the short was gone -> now after fluxing the pads & soldering back L4010, the short to ground is gone?

If yes, I think the fault is fixed and was linked to the soldering of L4010 inductor.

The short to ground was probably linked to a pad of L4010 shorting to either C4013 or C1348.
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Old 11-04-2021, 10:14 PM   #22
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Default Re: 820-00244 PP5V_S0 shorted to ground

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Originally Posted by mon2 View Post
On a low voltage rail, low resistance like 60 ohms is ok.

So you are noting that L4010 had a short to ground -> you removed L4010 and the short was gone -> now after fluxing the pads & soldering back L4010, the short to ground is gone?

If yes, I think the fault is fixed and was linked to the soldering of L4010 inductor.

The short to ground was probably linked to a pad of L4010 shorting to either C4013 or C1348.
ok @mon2,

i will try to assemble everything now..will update ASAP
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Old 11-05-2021, 01:28 AM   #23
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Default Re: 820-00244 PP5V_S0 shorted to ground

can turn on but still keyboard and trackpad not function..but i can turn off with power button from keyboard..
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Old 11-05-2021, 04:46 AM   #24
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Default Re: 820-00244 PP5V_S0 shorted to ground

1) Check fuse F4800. Voltage on both sides ok for this fuse ?

2) Check the voltage @ PPBUS_G3H_TPAD_FLT, pin # 2 on inductor L4800 ?

3) J4801, voltage @ PP3V3_G3H_KBD_F ?

4) J4801, voltage @ PP5V_S0_KBD_F ?

5) J4801, voltage @ PP3V3_S4_TPAD_F ?

6) J4801, voltage @ PP5V_S4_TPAD_F ?
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Old 11-05-2021, 09:21 PM   #25
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Default Re: 820-00244 PP5V_S0 shorted to ground

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1) Check fuse F4800. Voltage on both sides ok for this fuse ?

2) Check the voltage @ PPBUS_G3H_TPAD_FLT, pin # 2 on inductor L4800 ?

3) J4801, voltage @ PP3V3_G3H_KBD_F ?

4) J4801, voltage @ PP5V_S0_KBD_F ?

5) J4801, voltage @ PP3V3_S4_TPAD_F ?

6) J4801, voltage @ PP5V_S4_TPAD_F ?
1. voltage on F4800 both sides 8.6V

2. PPBUS_G3H_TPAD_FLT, pin # 2 on inductor L4800 8.6V

3. PP3V3_G3H_KBD_F 3.29V

4. voltage @ PP5V_S0_KBD_F 5.1V

5. PP3V3_S4_TPAD_F 3.3V

6. PP5V_S4_TPAD_F 5V

everything seems normal...should i change the flexible?
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Old 11-07-2021, 10:27 PM   #26
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Default Re: 820-00244 PP5V_S0 shorted to ground

i just change the flexible and now all normal..
thanks to @mon2
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Old 11-10-2021, 04:41 AM   #27
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Default Re: 820-00244 PP5V_S0 shorted to ground

so weird....now it comes back and keyboard and trackpad not function...ic check the voltage all ok
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Old 11-10-2021, 06:28 AM   #28
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Default Re: 820-00244 PP5V_S0 shorted to ground

That sucks.

The issue may require you to replace the trackpad (most likely) and/or the keyboard (backup requirement). The technology of these 2 mated parts are not serviceable.

Did you check the attached location for their voltages?

We have had cases were the trackpad was the root cause and at least was causing a heatup of the logic board.

Do you have an oscilloscope? You can check for activity of the SPI interface used for the trackpad communications.

MISO = Master IN (logic board); Slave out (trackpad)
MOSI = Master OUT (logic board); Slave in (trackpad)
CLK = Clock used to frame the above SPI traffic and is generated by the SPI bus master (logic board)

Do you see activity on the above 3 lines with a scope ? As you move your finger about the trackpad, you should see bits flying by to denote the X, Y of the finger action.
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File Type: png tpad_voltage1.png (175.5 KB, 1 views)
File Type: png tpad_voltage2.png (225.9 KB, 1 views)
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Old 11-10-2021, 08:27 PM   #29
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Default Re: 820-00244 PP5V_S0 shorted to ground

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Originally Posted by mon2 View Post
That sucks.

The issue may require you to replace the trackpad (most likely) and/or the keyboard (backup requirement). The technology of these 2 mated parts are not serviceable.

Did you check the attached location for their voltages?

We have had cases were the trackpad was the root cause and at least was causing a heatup of the logic board.

Do you have an oscilloscope? You can check for activity of the SPI interface used for the trackpad communications.

MISO = Master IN (logic board); Slave out (trackpad)
MOSI = Master OUT (logic board); Slave in (trackpad)
CLK = Clock used to frame the above SPI traffic and is generated by the SPI bus master (logic board)

Do you see activity on the above 3 lines with a scope ? As you move your finger about the trackpad, you should see bits flying by to denote the X, Y of the finger action.
thanks for the reply @mon2
the keyboard is new changed by another shop..i tried to use trackpad from macbook 12" 2015 but still not working. ia m sorry @mon2 i dont have oscilloscope
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Old 11-10-2021, 08:38 PM   #30
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Default Re: 820-00244 PP5V_S0 shorted to ground

From here, check L4804.

https://boards.rossmanngroup.com/thr...eyboard.39416/
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Old 11-10-2021, 09:41 PM   #31
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Default Re: 820-00244 PP5V_S0 shorted to ground

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thanks a lot @mon2.. just check that L4802 is not connected on both side and replaced...now keyboard and trackpad working...hopefully this is all..
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Old 11-11-2021, 12:36 AM   #32
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Default Re: 820-00244 PP5V_S0 shorted to ground

and now.......trackpad and keyboard no function again....sigh
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Old 11-11-2021, 02:03 AM   #33
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Default Re: 820-00244 PP5V_S0 shorted to ground

Check that part again. It is possible that the current draw of the replacement keyboard and trackpad is higher than the rating of the applied inductor that passes the current. Then these interface inductors are acting like fuses. That is, may make sense to use higher current rated part for the location that is not working.
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Old 11-11-2021, 07:43 AM   #34
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Default Re: 820-00244 PP5V_S0 shorted to ground

the trackpad still original but the keyboard is not. so if you say like that if i disconnect keyboard and only connect trackpad with the logic board then the trackpad should function right? but it is not so what should i do now?
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Old 11-11-2021, 07:48 AM   #35
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Default Re: 820-00244 PP5V_S0 shorted to ground

No, I meant to check the voltage rails that power the trackpad & keyboard circuit.

See attached. Measure and post the voltages for each of these coils when the power is ON. Suspecting that one of these is not working.
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File Type: png keyboard_trackpad.png (81.0 KB, 4 views)
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Old 11-11-2021, 08:00 AM   #36
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Default Re: 820-00244 PP5V_S0 shorted to ground

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Originally Posted by mon2 View Post
No, I meant to check the voltage rails that power the trackpad & keyboard circuit.

See attached. Measure and post the voltages for each of these coils when the power is ON. Suspecting that one of these is not working.
ok @mon2, tomorrow i will check. many thanks
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