On a laptop motherboard... red circled component. Is quite broken. When the power adaptor is unplugged, I get the correct voltage from the adaptor. When I plug it into the laptop, it keeps bumping from 0v to 0.20v and back, as if it's trying to start but not getting anywhere.
Name that component
Collapse
X
-
Re: Name that component
Its a transistor that blew up, and is shorted. This would explain why the PSU goes into safety/shutdown when connected.<--- Badcaps.net Founder
Badcaps.net Services:
Motherboard Repair Services
----------------------------------------------
Badcaps.net Forum Members Folding Team
http://folding.stanford.edu/
Team : 49813
Join in!!
Team Stats -
Re: Name that component
I promise you'll get a cut :P
Ludicrous gibs!
Comment
-
Re: Name that component
You have to find out what it is. Look for the same model motherboard (or a good high-res pic of one) from a working unit. The transistor will have tiny numbers on it, and from there it can be identified, and most likely someplace like digikey will have a replacement for mere pennies.<--- Badcaps.net Founder
Badcaps.net Services:
Motherboard Repair Services
----------------------------------------------
Badcaps.net Forum Members Folding Team
http://folding.stanford.edu/
Team : 49813
Join in!!
Team StatsComment
-
Re: Name that component
If you gave all the laptop's information up front (and in the thread title... *hint*), there might be a member with the same board.
Also, a backed-off shot helps people locate it on their board.
Can you find the blown-off top piece to it? Could have viable numbers on it...veritas odium paritComment
-
Re: Name that component
Take it off and see if the adapter is still shorted by the board.Mann-Made Global Warming.
- We should be more concerned about the Intellectual Climate.
-
Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
- Dr Seuss
-
You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
-
Comment
-
Re: Name that component
These mods I say
Seriously a service manual would tell you too, look for Q23 in it..."The one who says it cannot be done should never interrupt the one who is doing it."Comment
-
Re: Name that component
There are a few ways of correctly finding this part is:
1. Looking into a service manual for Q23 on this board.
2. Find a parts list for the board that has Q23 listed.
3. Draw out the circuit of parts before and after this component to determine its use - then cross reference.
There really is no simple way. You might find out that it is nothing but a general purpose transistor. In that case, you can find them almost anywhere. The service manual would be the best though. I would search for one but we dont have any model numbers yet.The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS
Comment
-
Re: Name that component
I'd like to know where you guys are getting service manuals!! Last I ever knew, motherboard manufacturers don't release schematics and whitepapers for their boards.....so this would be a new wrinkle!<--- Badcaps.net Founder
Badcaps.net Services:
Motherboard Repair Services
----------------------------------------------
Badcaps.net Forum Members Folding Team
http://folding.stanford.edu/
Team : 49813
Join in!!
Team StatsComment
-
Re: Name that component
I've never seen a component level service manual for any mobo, let alone a laptop.
Intel server boards have docs that come close for some specific circuits [not the whole board] but that about as good as it gets.Mann-Made Global Warming.
- We should be more concerned about the Intellectual Climate.
-
Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
- Dr Seuss
-
You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
-
Comment
-
Re: Name that component
So, I removed the broken transistor, and there's no change in the behavior of the voltage.
I pulled the processor to make sure it's not shorted... still no luck. Would this require there be a battery present to kick over the charging/power circuit?Ludicrous gibs!
Comment
-
Re: Name that component
Could be something else shorted. A diode across input for reverse polarity protection?
What voltage are you reading with it disconnected from laptop?
When plugged in, are you measuring at the input jack to the laptop?
Is this the correct power pack for this computer? NW199AAveritas odium paritComment
-
Re: Name that component
Power pack (per HP) has built in overload protection. So, the jumping you're seeing is the PSU trying to come up, seeing the short, and cycling.
You're going to have to trace the input and find the component(s) that shorted. With the removal of the obvious bad transistor, the short (most likely) lies between it and the input.
I'm assuming this is your laptop and you've never used any other PSU except the HP one you have, correct?veritas odium paritComment
-
Re: Name that component
This is not my laptop... Working on it for a friend. I do not know its history, other than she said she left for a week and when she came back it didn't work anymore. I don't even have another similar laptop to be able to charge the battery and see if it runs off batt. In the meantime, I'm loaning her my spare laptop, and we'll go through the options of repairing (replace motherboard) or just buying a new one. Motherboard is around $225 off eBay.Ludicrous gibs!
Comment
-
Re: Name that component
Try measuring the voltage at the pads where you removed the transistor
To see if the voltage reaches this point or is blocked by something in the path to it"The one who says it cannot be done should never interrupt the one who is doing it."Comment
-
Re: Name that component
Then try tracing the circuit back from there untill you find whatever it is that stops the current from flowing"The one who says it cannot be done should never interrupt the one who is doing it."Comment
Related Topics
Collapse
-
This specification for the HP EliteBook 850 G5 + Mini Dock, Bag & Spare AC Adaptor Notebook can be useful for upgrading or repairing a laptop that is not working. As a community we are working through our specifications to add valuable data like the 850 G5 + Mini Dock, Bag & Spare AC Adaptor boardview and 850 G5 + Mini Dock, Bag & Spare AC Adaptor schematic. Our users have donated over 1 million documents which are being added to the site. This page will be updated soon with additional information. Alternatively you can request additional help from our users directly on the relevant...09-06-2024, 08:50 AM
-
by Simonc123Hi guys, I need a bit of help. I use a CH341A programmer, which is fine for 3.3v old-style bios chips. I need to reprogram some 1.8v chips, which are QFN type chips. I have the 1.8v adaptor for that slots onto the programmer, which does step the voltage down to 1.8v, but as you can see in the picture added, it doesn't fit in the IC holder.
Please see the 4th picture that shows what looks like what should work for the QFN IC (highlighted in red). The issue is that the 8 pads on the programmer are too long and short out the IC. Is it a case of putting kapton tape over the center ground...4 Photos-
Channel: General Computer & Tech Discussion
-
-
by ronelexMacbook Pro A1502 Adaptor Shorted When Battery Attach
Unit works on Battery Mode
Unit works on Adaptor Mode
But When Adaptor and Battery both attach, the charger plug overheat so much, when using PSU it draw 3A when battery is attach
Checking battery connector when adaptor only attach, J7050 PPVBAT_G3H_CONN measures 12v- 0v- 12v cycle and the mosfet driving Q7155 pin 4 measures 5v then 12v cycle -
Hi. I have been watching videos on how a power adaptor works.
There is explanation of the rectifier bridge to the pulse width modulator, the mosfet for switching, and opto-couplers, but there is little to nothing about the AC stage of the transformer the powers the primary coil.
So, I see that the PWM needs DC to work, but I don't see anything about how the AC gets from the mains supply to the transformer stage.
A transformer only works on AC so where is that part of the circuit.
I only see Capacitors on the output. Should I assume that the secondary coil and...-
Channel: General Computer & Tech Discussion
-
-
by apostsamkingHello everyone hope all is well. Pls I bought this second hand dell latitue e5450, I realize that the battery cannot be charged because it says ac adopter unknown at bios. I tried several chargers but still I get the same messageAC Adaptor unknown. So I open the laptop up checked the motherboard and i realised that the diod PD5 is fried so I changed, but I still get the same message, changed even the charging ic still the same message AC Adaptor unknown. Can any one help me?
- Loading...
- No more items.
Comment