Name that component

[dood]

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.

[Topcat]

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.

[dood]

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.

Any way to fix? I'm guessing if I just remove it, the board will still be dead. You hired on a mod that doesn't know much about transistor-level circuit designs. I've always drawn the line at caps. But, to fix this, instead of paying $200 for a new motherboard, will make me a hero I promise you'll get a cut :P

[Topcat]

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.

[Toasty]

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...

[PCBONEZ]

Re: Name that component

Take it off and see if the adapter is still shorted by the board.

[Per Hansson]

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.

Hahaha, awsome quote of the day!
These mods I say

Seriously a service manual would tell you too, look for Q23 in it...

[dood]

Re: Name that component

I guess I shouldn't post so late at night. I was kind of out of it. Anyway, I'll get the requested information when I get home after work today.

[Dgtech]

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.

[Topcat]

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!

[PCBONEZ]

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.

[dood]

Re: Name that component

Okay, Laptop is an HP G60, and the motherboard is HP PN 578999-001

[dood]

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?

[Toasty]

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? NW199AA

[dood]

Re: Name that component

Power pack is showing 18.5v when disconnected from the laptop.

When plugged in, I'm measuring from the input jack.

The power pack I have is the original. PN 463552-004

[Toasty]

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?

[dood]

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.

[Per Hansson]

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

[dood]

Re: Name that component

I only got 0.01 volt at the top two pads.

[Per Hansson]

Re: Name that component

Then try tracing the circuit back from there untill you find whatever it is that stops the current from flowing