Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting Laptops, Portable, and Mobile Devices
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 05-01-2019, 03:54 AM   #1
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Alienware 18 LA-9332P 3V, 5V short

Hi, as far as I can tell, this board has a short on 3VALW and 5VALW and I am currently stuck on what to do next.

PU100 gets hot when the AC adapter is connected so I assume it's shorted so I have removed it for testing.

QZ1 is grounded on pins 1, 2, 3, 5, 6, 7, 8.

PQ104 pin 5 grounds the DC jack shorting the AC adapter so I have removed it.

PL102 is grounded on pin 1.

PL101 is grounded on pin 1.

PL501, PL502, PL503 and PL504 are grounded when the CPU is in, they are ungrounded when the CPU is removed.

PL201 is grounded.

QZ3 is grounded on pins 1, 2, 3, 5, 6, 7, 8.

PQ201 is shorting the DC jack also and is removed for testing other stuff.

As far as I can tell, 3VALW and 5VALW are shorted somehow and I have come to an end on where to go next so I;m acking the experts on what could be going on. Thanks :-)
Attached Files
File Type: pdf compal_la-9332p_rx02_schematics.pdf (1.49 MB, 21 views)

Last edited by Johndill; 05-01-2019 at 03:56 AM..
Johndill is offline   Reply With Quote
Old 05-01-2019, 05:14 AM   #2
piernov
Badcaps Veteran
 
Join Date: Jan 2016
City & State: Valbonne, 06
My Country: France
I'm a: Knowledge Seeker
Posts: 1,115
Default Re: Alienware 18 LA-9332P 3V, 5V short

It's not always safe to remove a buck controller and power on the board because then the gates of the high-side MOSFET are floating, and they could pass current, meaning sending 19V to the 3V or 5V rail. If you need to power on the board with the buck controller removed, either disconnect the PJP jumper, remove the output inductor or remove the high side MOSFET.

Ignore PL501, PL502, PL503 and PL504, it's normal to have low resistance to ground there with CPU inside the socket.

You have several places shorted to ground that should not be shorted together and are mostly unrelated. I'm not sure what happened but this doesn't look good.
It's especially concerning to have PQ201 shorted but for now ignore that circuit as the 3V/5V circuit must be fixed first.


You should try to isolate the shorts as much as possible, so remove QZ1 and QZ3 (which are probably dead anyway) and check which side is shorted for both.

Disconnect PJP100, PJP101 and PJP102 and check which sides are shorted too. If they cannot be disconnected, remove PL101 and PL102.

Also check for a short to ground on pin 3 and pin 13 of PU100.
__________________
OpenBoardview http://openboardview.org | IRC #openboardview@irc.freenode.net
piernov is offline   Reply With Quote
Old 05-01-2019, 08:25 AM   #3
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

Quote:
Originally Posted by piernov View Post
It's not always safe to remove a buck controller and power on the board because then the gates of the high-side MOSFET are floating, and they could pass current, meaning sending 19V to the 3V or 5V rail. If you need to power on the board with the buck controller removed, either disconnect the PJP jumper, remove the output inductor or remove the high side MOSFET.

Ignore PL501, PL502, PL503 and PL504, it's normal to have low resistance to ground there with CPU inside the socket.

You have several places shorted to ground that should not be shorted together and are mostly unrelated. I'm not sure what happened but this doesn't look good.
It's especially concerning to have PQ201 shorted but for now ignore that circuit as the 3V/5V circuit must be fixed first.


You should try to isolate the shorts as much as possible, so remove QZ1 and QZ3 (which are probably dead anyway) and check which side is shorted for both.

Disconnect PJP100, PJP101 and PJP102 and check which sides are shorted too. If they cannot be disconnected, remove PL101 and PL102.

Also check for a short to ground on pin 3 and pin 13 of PU100.
I've replaced everything I removed except PL101 and PL102 as I removed them to isolate the short earlier.

QZ1 removed:
pins 1, 2, 3, 5, 6, 7, 8 shorted, pin 4 good.

QZ3 removed:
pins 1, 2, 3, 5, 6, 7, 8 shorted, pin 4 good.

PL101 already removed:
pin 1 short
pin 2 good

PL102 already removed:
pin 1 short
pin 2 short

PU100:
pin 3 good
pin 13 good
found pin 12 short

cap PC117 short to ground, short was gone when I removed PU100 earlier.

Last edited by Johndill; 05-01-2019 at 08:30 AM..
Johndill is offline   Reply With Quote
Old 05-01-2019, 08:30 AM   #4
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

Please refresh as I have corrected some mistakes ^^^
Johndill is offline   Reply With Quote
Old 05-05-2019, 05:10 PM   #5
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

What should I try next?
Johndill is offline   Reply With Quote
Old 05-06-2019, 09:51 PM   #6
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

Bump.
Johndill is offline   Reply With Quote
Old 05-09-2019, 01:54 AM   #7
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

I'm not sure what else to test from here, suggestions?
Johndill is offline   Reply With Quote
Old 05-14-2019, 05:48 PM   #8
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

Am I alone? It's so cold in here.

Last edited by Johndill; 05-14-2019 at 05:50 PM..
Johndill is offline   Reply With Quote
Old 05-14-2019, 11:15 PM   #9
ktmmotocross
Boardkiller
 
ktmmotocross's Avatar
 
Join Date: Feb 2014
City & State: slovakia
My Country: slovakia
Line Voltage: 230VAC 50Hz
I'm a: Hobbyist Tech
Posts: 1,725
Default Re: Alienware 18 LA-9332P 3V, 5V short

to be sure u mean short is resistance under 2ohms?

to locate short remove all components where u find shortted pins

Last edited by ktmmotocross; 05-14-2019 at 11:16 PM..
ktmmotocross is offline   Reply With Quote
Old 05-15-2019, 09:53 PM   #10
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

Quote:
Originally Posted by ktmmotocross View Post
to be sure u mean short is resistance under 2ohms?

to locate short remove all components where u find shortted pins
Yes, short is under 2 ohms and continuity to ground.

That has been done in the previous posts but have still been unable to find the main short.
Johndill is offline   Reply With Quote
Old 05-16-2019, 11:51 AM   #11
ktmmotocross
Boardkiller
 
ktmmotocross's Avatar
 
Join Date: Feb 2014
City & State: slovakia
My Country: slovakia
Line Voltage: 230VAC 50Hz
I'm a: Hobbyist Tech
Posts: 1,725
Default Re: Alienware 18 LA-9332P 3V, 5V short

there are too many shorts. did u remove pu100 and check?
ktmmotocross is offline   Reply With Quote
Old 05-16-2019, 12:45 PM   #12
khaahk
Badcaps Veteran
 
khaahk's Avatar
 
Join Date: Dec 2013
City & State: Tallinn
My Country: Estonia
I'm a: Knowledge Seeker
Posts: 566
Default Re: Alienware 18 LA-9332P 3V, 5V short

Use lab PSU to find shorts in +3VALW and +3VS, the same with +5VALW and +5VS rails. It is most likely not an easy job - probably need to replace many components (maybe too many). If successful then replace PU100 and PU200, measure mosfets - change if needed, check ram chip for short.
khaahk is offline   Reply With Quote
Old 05-16-2019, 04:45 PM   #13
Johndill
Badcaps Veteran
 
Join Date: Aug 2015
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 257
Default Re: Alienware 18 LA-9332P 3V, 5V short

Quote:
Originally Posted by ktmmotocross View Post
there are too many shorts. did u remove pu100 and check?
Yes, PU100 was removed in post#1, however the shorts remained.

Quote:
Originally Posted by khaahk View Post
Use lab PSU to find shorts in +3VALW and +3VS, the same with +5VALW and +5VS rails. It is most likely not an easy job - probably need to replace many components (maybe too many). If successful then replace PU100 and PU200, measure mosfets - change if needed, check ram chip for short.
I have been looking for a donor board for parts but from what both of you are saying, mine will be better off being the donor board instead, if I can find another AW 18 board to repair.
Johndill is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2019
Powered by vBulletin ®
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 06:44 AM.
Did you find this forum helpful?