Acer Not Powering la-k701p

[kalilinux25]

Re: Acer Not Powering la-k701p

EC_RSMRST# -0v This is cause of concern. Without RSMRST# present, you cant expect get anything from PCH like PM_SLP_X. Try removing DB2/DB/3/DB4 one by one and see any changes happens or not. However, before RSMRST# 1.05V/1.8V ALW rails should be present.

tried remove all db3 db4 db2 and tried to run display unit on start fan speed , 3 times unit restarted and until display is present. Ill try to stress test the unit if everything is totally functional sir.

[mcplslg123]

Re: Acer Not Powering la-k701p

Glad, you fixed it again. I suggested to remove these 3 diodes one by one so that we can identify which one is faulty. Perhaps you hurried up a bit.

PS: That particular diode we're looking for may be faulty(very unlikely) or that voltage rail's powergood is missing. Usually replacing the PWM on that rail is recommended and test the unit with all the diodes soldered back for stability.

[kalilinux25]

Re: Acer Not Powering la-k701p

Glad, you fixed it again. I suggested to remove these 3 diodes one by one so that we can identify which one is faulty. Perhaps you hurried up a bit.

PS: That particular diode we're looking for may be faulty(very unlikely) or that voltage rail's powergood is missing. Usually replacing the PWM on that rail is recommended and test the unit with all the diodes soldered back for stability.

will it last without those diode? or do I ned to change a pwm and which one specificsir ?

[mcplslg123]

Re: Acer Not Powering la-k701p

will it last without those diode? or do I ned to change a pwm and which one specificsir ?

How i can confirm which PWM is responsible when you didnt removed them one by one.

Yes, it should last without these diodes.

[kalilinux25]

Re: Acer Not Powering la-k701p

How i can confirm which PWM is responsible when you didnt removed them one by one.

Yes, it should last without these diodes.

ill try it again sir one by one again to pin point the pmw sorry I hurried again without trying the basic steps mybad

[mcplslg123]

Re: Acer Not Powering la-k701p

Let it go this time but dont loose patience next time. Btw, i helped you fix this board twice in a row-so you owe me a coffee.

[kalilinux25]

Re: Acer Not Powering la-k701p

Let it go this time but dont loose patience next time. Btw, i helped you fix this board twice in a row-so you owe me a coffee.

Thanks sir , Ill do my best during the process, im having a refresher course again because I stop doing repairs for a while .

[tblazers]

Re: Acer Not Powering la-k701p

Thanks sir , Ill do my best during the process, im having a refresher course again because I stop doing repairs for a while .

I have a similar issue, which diode ended up being the correct one that was removed? and did you jump it once it was removed ?

[mcplslg123]

Re: Acer Not Powering la-k701p

Diode should not be jumpered.One solution may not fit in all cases. Describe your problem details for better clarity.

[tblazers]

Re: Acer Not Powering la-k701p

Sorry i made my own post now here
https://www.badcaps.net/forum/showthread.php?t=120768

[EpicFix]

Hi guys, total noob here I have an Acer board in with “no power” issue. GH5JJ / GH7JJ LA-K701P Rev 1 C.

@ PRB3 I get 18v (7Mohms)

19v comes up to PCB8, PCB9, PCB10 but nothing goes into PQB5.

Side note:
PC501, PC506, PC503, PC504, PC505 all continuous with ground on both ends but the shorts are released when PU501 is removed.
PL502 is also continuous to ground on both ends (along with all the caps PC508 to PC513) even after PU501 is removed.

If anyone can offer me some guidance on where I can check next I'll be super grateful. How / where do I detect shorts?

[mon2]

See attached. This means everyone to the RIGHT side of this PU501 is a suspect.

I would start with checking the USB connectors since VBUS is used to power the USB devices. The local load switch often fails.

Remove all power. Meter in resistance mode. What is the exact resistance to ground of +5VALW_USBA? If the resistance is ok and not a short, move onto reviewing JPQ3. Remove this short / solder blob.

Is the short condition now gone?

[EpicFix]

See attached. This means everyone to the RIGHT side of this PU501 is a suspect.

I would start with checking the USB connectors since VBUS is used to power the USB devices. The local load switch often fails.

Remove all power. Meter in resistance mode. What is the exact resistance to ground of +5VALW_USBA? If the resistance is ok and not a short, move onto reviewing JPQ3. Remove this short / solder blob.

Is the short condition now gone?

I checked @ UT10 the resistance is 2.2 Ohms. Is that a short?

[mon2]

100% a short. Flux and remove this part. Then test if the short is gone or not.

[EpicFix]

100% a short. Flux and remove this part. Then test if the short is gone or not.

Removed...... still shorts. PL502 is also continuous to ground on both ends (along with all the caps PC508 to PC513)

[mon2]

Remove the solder blob @ PJ501. This will isolate the 2 sides of this shorted rail. Then measure each side of the removed solder blob.

Which side is still shorted?

[EpicFix]

Remove the solder blob @ PJ501. This will isolate the 2 sides of this shorted rail. Then measure each side of the removed solder blob.

Which side is still shorted?

PJ501 removed. Shorts gone from PL502 and the surrounding caps (PC508 to PC513). Resistance @ UT10 now 7.8 Ohms @ PIN 5, 13 MOhms @ PIN 1 (both readings done with the component removed). I checked the component off-board PINS 1,2 and 5 are continuous. The pads on the board for UT10 (PIN 2 and PIN 5) are continuous between themselves and also to ground. Is that still shorted? Where do I go next?

[mon2]

Would you have a thermal camera?

[EpicFix]

Would you have a thermal camera?

Yes I do, but its not a very good one FLIR C5. I also have a bench supply and a "short killer" / voltage injection tool. It's reading schematics and figuring out problem circuits I'm a noob at 🤣

[mon2]

We too have the 'short killer 30A' !! Good taste. My only complaint is that the display is a bit dim from day #1 so not supper happy with the vendor.

Be 100% that the pin with the low resistance is not ground. Fairly confident that you are doing this properly so far. Dial up 0v8 on the display. We want to keep the voltage as low as possible. Then apply the short killer onto the pad with the low resistance. Check who heats up. Hope it is a capacitor. The injection should smoke out the shorted part.