thankyou for that great information... I am still learning.
as original post states, there are no 'obvious' shorts on the board unless the low value i do get at the cpu inductors, but i thought that was to be expected anyway ? (like, 1-3 ohms?)
Ill post results of checking resistance to GND . If i inject 1v to the CPU coil, will that indicate a blown CPU on thermal camera?
again many thanks...
zlr8r
Senior Member
Last Activity: Yesterday, 11:36 AM
Joined: 02-13-2023
Location: N.Ireland
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Thanks for info.
I do seem to be getting all necessary voltages to make the board work.
In thermal view, I see [B]just 3[/B] inductors heating up along with the cpu.
The rest of the board is ice cold.... including the small die on the CPU. it almost seems like there is no power getting to the smaller die ?
If that was the case, what would cause that and where on the board can i check to verify ?
If the CPU was dead as you say, would it power up at all ? How can i test this ?
If i repeat power connection connecting the battery,...Leave a comment:
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can anyone offer advice ? thanksLeave a comment:
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HP Probook 640 G5 - replaced blown components, getting power led, fan full, 5-flashes on CAPS Lock and NUM lock, black screen
Hey guys, bit stumped with this laptop after replacing 2 blown components i.e., MP86493, MP2979A.
To begin with, this laptop was dead-dead.
Now with replaced (visibly) blown components, i do get some progress; after connecting battery or main cable;[LIST][*]am getting white power led[*]5-long-flashes on CAPS Lock and NUM lock[*]then, fan full speed[*]CPU heats up some (smaller die PCH, does not)[*]always constant black screen no matter what's tried[*]no USB recognition[*]no HDMI output[/LIST]this is as far as I can get with it and not sure where to inspect next ?
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scrapped the laptop as I couldn't pinpoint the exact problem component. Thanks to all those who tried to help.Leave a comment:
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any recommendations for next step in repair ? replace charging IC, and maybe RAM controller IC ? thanksLeave a comment:
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thanks, where should i be looking next to locate fault ?Leave a comment:
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Values ; [B][I]source / drain resistance, source / gate resistance, gate / drain resistance.[/I][/B]
[B](top-left mosfet)[/B]
0.6 MΩ S - D
none - S - G
none - G - D
[B](top-right mosfet[/B][B])[/B]
2.5 MΩ - S - D
none - S - G
none - G - D
[B](lower-left mosfet[/B][B] )[/B]
3.2 MΩ - S - D
none - S - G
none - G - D
[B](lower-right mosfet[/B][B])[/B]
0.9 MΩ - S - D
none - S - G
none - G - DValues ; [B][I]source / drain resistance, source / gate resistance, gate / drain resistance.[/I][/B]Leave a comment:
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whoops! apologies, ignore previous values, i forgot i had removed a big coil directly from the other side of the board from those 4 mosfets.
i soldered it back on and the correct values are ;
[B](top left)[/B]
1.1 MΩ - D
1.5 MΩ - S
none - G
[B](top right)[/B]
1.5 MΩ - D
0.2 Ω - S
none - G
[B](lower-left)[/B]
1.5 MΩ - D
0.2 Ω - S
none - G
[B](lower-right)[/B]
2.5 MΩ - D
1.1 MΩ - S
none - G
do you still want me to complete your...Leave a comment:
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ok, for all 4 of those grouped mosfet's, the values [U]with the [B]Charging IC[/B] removed[/U] (D,S,G to GND), are ;
[URL=filedata/fetch?id=3205532&d=1706373405][ATTACH=JSON]{"alt":"Click image for larger version Name:\tCHARGING-IC.png Views:\t0 Size:\t206.5 KB ID:\t3205532","data-align":"left","data-attachmentid":"3205532","data-size":"custom","height":"130","title":"CHARGING-IC.png","width":"231"}[/ATTACH][/URL]
...Leave a comment:
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Hi, does anyone here have a Boardview file for this motherboard , thanks ?Leave a comment:
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Hi, sorry for the delay.
with bare motherboard on bench, no power, no battery, on that lower right mosfet I am seeing the following values. (it may be already burned though).
80 kΩ - [B]S[/B]
OL - [B]G[/B] (meter value rises to a MΩ point then goes to OL)
155 kΩ - [B]D[/B]Hi, sorry for the delay.
with bare motherboard on bench, no power, no battery, on that lower right mosfet I am seeing the following values. (it may be already burned though).
80 kΩ - [B]S[/B]
OL - [B]G[/B] (meter value rises to a MΩ point then goes to OL)...Leave a comment:
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ok, bit of a delay waiting on replacement mosfets coming from China.
Okay, I installed all 4 mosfets just to be sure. Reconnected the 19v charger.
Same thing happens as before, power light comes on for about 2-3 seconds and then goes off.
Or, the amber light flashes 3 times followed by 5 white lights. At same time, the CPU is getting extremely hot , and I can hear a whine from a coil somewhere, and then the same mosfet on the lower-right of image ends up blowing (shorts itself out after getting extremely hot - so hot I burned a square into my thumb lol)...?...Leave a comment:
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many thanks. If im replacing 1 i may as well do the 4 since its going to take 3 weeks for them to come from China....
While im waiting on those , is there anything else I should be checking on the board for possible issues ?
thanks...Leave a comment:
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[ATTACH=JSON]{"alt":"Click image for larger version Name:\tmosfet+cap_removed-edit.png Views:\t0 Size:\t6.18 MB ID:\t3165735","data-align":"left","data-attachmentid":"3165735","data-linktype":"2","data-size":"custom","height":"279","title":"mosfet+cap_removed-edit.png","width":"536"}[/ATTACH][ATTACH=JSON]{"alt":"Click image for larger version Name:\tmosfet+cap_removed-values.jpg Views:\t0 Size:\t51.1 KB ID:\t3165737","data-align":"none","data-attachmentid":"3165737","data-linktype":"2","data-size":"custom","height":"306","title":"mosfet+cap_removed-values.jpg","width":"489"}[/ATTACH]...
Last edited by zlr8r; 12-20-2023, 11:54 AM.Leave a comment:
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Indeed, lower-right mosfet removed and getting a short on it between Source and Drain.
Good reading on its motherboard pads and other 3 mosfets (around 520 Ohms)....Last edited by zlr8r; 12-20-2023, 11:49 AM.Leave a comment:
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PPU403 mosfet removed , and getting a direct short on it between Source and Drain.Leave a comment:
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ok, I removed the Cap nearest to the lower-right mosfet. The resistance now on that mosfet is now, 42 Ohms (was 26 Ohms before removing the nearby Cap).
I also see a direct short between Source and Drain on that lower-right mosfet ? Should I now remove it and retest ?
cheers
[ATTACH=JSON]{"alt":"Click image for larger version Name:\tfetch?id=3165589&d=1703073249&type=medium.jpg Views:\t0 Size:\t38.0 KB ID:\t3165675","data-align":"none","data-attachmentid":"3165675","data-size":"full","title":"fetch?id=3165589&d=1703073249&type=medium.jpg"}[/ATTACH]...Leave a comment:
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