Asus Q502L does not boot up properly

[SMDFlea]

Re: Asus Q502L does not boot up properly

I think PQ8102 is the culprit.Remove it and see if PU8100 still gets hot. I`d get a 2nd opinion from @caspian though.

[tibimakai]

Re: Asus Q502L does not boot up properly

I will remove both FETs(PQ8102 & 8103) and see what happens.

[tibimakai]

Re: Asus Q502L does not boot up properly

So there is no short, but for some reason, the output voltage is very low. 5V is 0.156V(76 Ohm) and 3.3V, is 0.043V(48 Ohm). PU8100 still getting hot.

[SMDFlea]

Re: Asus Q502L does not boot up properly

I think its just a process of elimination at this point.You removed PQ8102,8103 ,look at what else is connected to pin 18 of PU8100 ,theres PR8107,PC8106 and PL8101 . Remove all those parts and do a brief power test ,if the PU8100 still gets hot solder those parts back on,and go onto the next pin e.g. pin 1 - remove PR8103

[tibimakai]

Re: Asus Q502L does not boot up properly

Thank you, I will try that.
What is low resistance, is pin #4, at only 2 Ohm.
Do you think, that it's OK? To me, it sounds way to low.

[tibimakai]

Re: Asus Q502L does not boot up properly

I have been busy lately, with other stuff. I'm not giving up.
I'm also working on an Onkyo home theater that had a power surge, so has a short somewhere. Working on my garage as well.
I was thinking, that is a good idea to remove the two FETs(PQ8102 & PQ8103), from the output of PU8100 and turn it on? Or only, with the solder bridge(PJP8101) removed?

[caspian]

Re: Asus Q502L does not boot up properly

it is great that you are back. I was away last week too. So I did not see the posts in page5 before. If you work on this laptop more often, Badcaps technicians do not forget the repair details, so they can help you better. If a big time gap is made between updates in this thread, I will forget the details and I have to read all the previous posts again. So far, I think you replaced PU8100 once. Please upload a photo of PU8100 and the components near it. If there is still any short there, do not connect power to the laptop. At this point, you have to remove a number of components until all the shorts are completely removed. First remove PQ8102 and PQ8103 and PJP8101. Then, if there is a short, remove PU8100. Then, if there is a short, remove the capacitors near PU8100. I hope there is a local IC supply, so that you can order and replace any IC easily. Thus, start removing them using a hot air station.

[tibimakai]

Re: Asus Q502L does not boot up properly

I will come back to this, this weekend. Sorry about that, but I have a water pipe leak issue, my car had some issues, my wife's Kenwood unit died.

[SMDFlea]

Re: Asus Q502L does not boot up properly

Bad luck comes in threes. If you want to repair the kenwood - https://www.badcaps.net/forum/forumdisplay.php?f=8

[tibimakai]

Re: Asus Q502L does not boot up properly

Sorry, I don't get it with that link.
The only thing that happens with it, is the backlight comes on, the red triangular(reset button) LED and the fan.

[tibimakai]

Re: Asus Q502L does not boot up properly

I took that picture. PCB is not cleaned, as you can see.

[tibimakai]

Re: Asus Q502L does not boot up properly

Any help?

[SMDFlea]

Re: Asus Q502L does not boot up properly

Any help?

Yes, just need some time to read through the thread again.

[tibimakai]

Re: Asus Q502L does not boot up properly

Sorry about that.
This was pointed toward caspian.

[caspian]

Re: Asus Q502L does not boot up properly

First you have to remove the shorts. what have you done from the removing jobs that were recommended in Post88?

[tibimakai]

Re: Asus Q502L does not boot up properly

Forget about those, I will remove them today.

[tibimakai]

Re: Asus Q502L does not boot up properly

OK, I have removed PQ8102, PQ8103 and opened up PJP8101. At pin #18 of PU8100 I'm getting only 3.5V, and PU8100 is still hot.
At coil PL8101(main 5V coil), I measure 77 Ohm. At coil PL8100(main 3.3V coil), I measure 15.7 Ohm.

[caspian]

Re: Asus Q502L does not boot up properly

now, it is time to remove PU8100. then remeasure the resistances mentioned in Post98. then, keep PU8100 removed to be able to do some more measurements.

[tibimakai]

Re: Asus Q502L does not boot up properly

Sorry to be so late, but I'm working on multiple devices.
I have removed the PU8100(new once came in as well) and I have measured all the pins, here are the results:
Pin #1= 36.2K, Pin #2= ~7K, Pin #3= 2 Ohm, Pin #4= 10k, Pin #5= 36K, Pin #6= 220K and goes up, Pin #7= 94K, Pin #8= 15.6K, Pin #9= OL, Pin #10= 10K, Pin #11= OL, Pin #12= 6k goes down, Pin #13= 5M and goes up, Pin #14= ~14K, Pin #15= OL, Pin #16=23K and goes up, Pin #17= OL, Pin #18= 15K and it goes up, Pin #19= 170M and goes up, Pin #20= 200k and goes up.
At PL8101, it starts around 1M, than drops and then goes up toward 15k.
At PL8100 it is a stable 15.6 Ohm.

[caspian]

Re: Asus Q502L does not boot up properly

now remove PQ8100, PQ8101 and open up PJP8102, PJP8103, PJP8104, and PJP8105. then, connect PJP8101. then, measure resistance on PL8100. keep previous components removed.