HP EliteBook 840 not charging not turning on, motherboard repair

If you realized HP Elitebook 840 series have been failing a lot in recent years, which I think is due to time since they have been in existence for almost 10 years. Today I decided to share a video demonstrating how to disassemble, diagnose and fix an HP laptop that does not turn on or charge.
This is very common, where a laptop standby voltage control IC fails to create first stage volts that enable the system to power on.
The chip I replaced is called TPS51225, it's very common in laptop motherboards with 4th Gen processors, like HP 820, Dell 6440, etc.

[@uxeys1k791]

0:42 saved me, I checked adapter and it wasnt working and just yellow and white lights blinking. now everything fixed. Thanks a lot.

[@escobarvon6065]

Thanks, it was really helpful. At least I know where the fault is from

[@platinumphonesandcomputers]

You are welcome

[@LeAdri1du40]

Most cowboy repair I've ever seen, amazed it worked, the soldering iron and air blower are way too big for smd and measuring a live motherboard, my man likes risks

[@platinumphonesandcomputers]

hahaha thanks

[@030H]

Well done 👍

[@icewater4723]

Hi, friend! I have the 850 g4 laptop, but there is a problem, it won’t turn on. I measured it on the incoming mosfet. 19 volts come to the D contact, and only 1.6 volts to G and S. What could be the problem?

[@soblez334]

Thank you very much Platinum Phones & Computer,
Pls i need your help for explanation, cause as a beginner, is not really profitable to me without explanation

[@platinumphonesandcomputers]

Thank you, We can organize for online classes on Zoom, contact me

[@АлександрКулаков-х1х]

Спасибо, помогли решить головоломку.

[@in2Rafi]

My HP Elitbook 840 laptop is sometimes charging but sometimes not charging at all. Moreover its not running without battery. How can I solve the issue?

[@michaelcosta7235]

Laptop was working fine but not charging. Did this procedure and now it won't power on.

[@clintonaligwo]

Please can a g2 voltage chip work for g3?

[@platinumphonesandcomputers]

No they are different

[@clintonaligwo]

@@platinumphonesandcomputers alright

[@rubengabrelian4997]

Hi there, where are you located?

[@platinumphonesandcomputers]

Uganda

[@universejorel]

hi my hp folio 1040 works on charger but it dosen't with the battery even if replaced. any ideas?

[@platinumphonesandcomputers]

Its most times due to the MOSFETs that allow battery voltage to the main rail not opening. You may need to check there it can be fault or short

[@hrishikeshprabhakar8024]

आप कहां के हैं मेरा भी लैपटॉप hp Elitebook 840 है जो चालू करने पर दो बार लाईट जलाकर बंद हो जाता है दिखाए तो बोले पावर बतम लोक टूट गया है जो नहीं बनता है

[@emiratemuhammad5752]

Can you please share hp 840 G1 continues blinking light once, when you plugged in adapter and it doesn’t turn on

[@platinumphonesandcomputers]

continues blinks depends on which led is exactly blinking, but probably adapter without middle pin does
A fault ram however this include caps lock and num 3 times
And a fault bios firmware

[@camerondavis2012]

hey so i didnt have 5v at the LDO but i did have the 3.2v on the LDO is mine the same problem that needs to be fixed

[@platinumphonesandcomputers]

Try checking the condition of the 5V LDO regulator, or disconnect the external 5v LDO circuit and see if 5V comes up

[@OnlyPcMobilegames]

My laptop hp Elite book g1 840 buttom side heating and "power led on" .
heating only and not power on

[@platinumphonesandcomputers]

You can follow this video to fix it.
th-cam.com/video/lX69uFGHDj0/w-d-xo.html

[@zaharaddeenel-hassan1771]

Please I have HP 1040 g2 is the same problem could it be the same solution?

[@platinumphonesandcomputers]

probably, follow the video and check for those volts rails

[@patrickmusyokimutiti3331]

Do you do repairs?

[@platinumphonesandcomputers]

That is obvious

[@richardappow6770]

what is the name of your multimeter and where to buy one?

[@platinumphonesandcomputers]

Its called Chengfa 98A+, this specific brand is rare these days but if you search for auto range multimeters you can find some like this

[@paulomiguel1201]

Parabéns!!

[@platinumphonesandcomputers]

obrigada

[@judychebet617]

where can we find your services here in Kenya Nairobi

[@platinumphonesandcomputers]

In Uganda

[@rough274]

How did you get the replacement chip?

[@platinumphonesandcomputers]

I salvaged it from another donor board

[@TFT00852]

Bhai Mera bhi repair kr doge

[@melaniemariner9703]

Hi can you please confirm the name of the part you called (voltage chip) and where I can get one please?

[@platinumphonesandcomputers]

Hey, that chip is TPS51225 made by Texas instruments, you can get it from other 4th Gen Motherboards' on some online websites.

[@melaniemariner9703]

@@platinumphonesandcomputers hi thanks for your reply when I test it as it is it shows around 3v or just over on some of the terminals am I too assume it's suppose to be 5v or 19 consistently?

[@platinumphonesandcomputers]

Now the processor of diagnosing that chip is a bit complex, it has 4 voltage regulators inside, each giving out two 3.3Volts and two 5Volts. 19 or battery voltage should be present on Vin and power MOSFETs, however, there are also other enable and reference volts that should be present to enable the chip to make those volts.

[@VictorBamgbade-cg8rk]

Please I have the same PC with this same prob

[@km.younus.79]

amr same modeler laptoper same problem, apni solve kore dite parben??

[@platinumphonesandcomputers]

can you write in english

[@exceptionalfahim2709]

Vai thik koraicen?

[@macchiato0122]

What is name of this part ?

[@platinumphonesandcomputers]

can you quote the time stamp of the exact part you would like to know

[@exceptionalfahim2709]

Where are you from bro?

[@platinumphonesandcomputers]

From Uganda

[@exceptionalfahim2709]

@@platinumphonesandcomputers bro i face this problem from two days. Naw what can i do?

[@platinumphonesandcomputers]

@@exceptionalfahim2709 you can follow the video and fix it

[@exceptionalfahim2709]

@@platinumphonesandcomputers bro, what is the name of this problem?
I will repeare it from any it center.

[@km.younus.79]

Vai apner phone number diyen, plz

[@Kiyingiprime-pg8db]

Bro help mi your contact m in uganda