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Old 01-19-2019, 05:36 PM   #41
BlueMidnight
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Alright, it's not going to give up its secrets that easily. So when you get your power supply, it's going to go as follows:

- Set a voltage limit of 3V.
- Start current limit at 0.
- Either clip the ground lead to a screw hole at the edge of the board, or solder a wire to a suitable ground point and clip the ground lead to the wire instead.
- Solder a wire to the PL12 pad that still measures as shorted (or reattach PL12 and solder directly to PL12 itself), and then clip the positive lead to that wire.
- Slowly ramp up the current.

The actual voltage shouldn't even reach your limit since the resistance is too low. But it will edge up slowly as the current increases.

We don't know where the short is, so we don't know how much current will be required to find it. If a small component (like a surface mount capacitor) is shorted, then it won't take much power to get it hot. But if a larger chip is the culprit, then it might take a lot more to get it warm.

I'd say set it to 100mA. And if everything looks good, starting moving it up to 500mA, 1A, 1.5A, etc. At each level you must touch every single little component (including the tiny surface mount parts) on the board to see if they are getting warm.

If you narrow the warmth to a small area, but can't decide which component is the source of the heat, you can use drops of isopropyl alcohol. The warmest spot will be where it evaporates first.

No heatsink is required during this test.
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Old 01-20-2019, 09:56 PM   #42
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I'm hoping my dc supply will arrive on Monday, in the meantime, I will prep the board with those wires on ground and PL12, shorted side.Lets hope its something nice and easy to find.
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Old 01-22-2019, 03:15 PM   #43
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Power Supply arrived, I found the little trouble maker. first tiny resistor, next to the 144pin chip. resistor got hot as hell. its right next to the large circle on the chip. will load a pic but don't know how to mark the resistor.

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Old 01-22-2019, 03:52 PM   #44
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I can't seem to load my picture, On pic 3, the 144 pin chip. There is a large circle on the left side of the chip. Its the first tiny resistor next to the first pin of the chip on the left hand side of the chip. Will continue to try and load my picture.Going to put PL12 back on board. I would assume you will want me to remove that small resistor to see if short goes away.
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Old 01-22-2019, 03:59 PM   #45
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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I can't seem to load my picture, On pic 3, the 144 pin chip. There is a large circle on the left side of the chip. Its the first tiny resistor next to the first pin of the chip on the left hand side of the chip. Will continue to try and load my picture.Going to put PL12 back on board. I would assume you will want me to remove that small resistor to see if short goes away.
I got it to load.
Attached Images
File Type: jpg 20190122_155842.jpg (599.2 KB, 19 views)
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Old 01-22-2019, 04:27 PM   #46
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I'm not sure if you are using your phone, PC, etc, to upload things. On the PC, I use FastStone Image Viewer ('D' key) or IrfanView ('F12' key) to do annotations, though it can be done in Paint or other similar apps too.

You can also use the boardview posted earlier to find the name of the hot component.

Pointing works just fine too. Heh

Actually, that is a capacitor with the identifier C550. That's a good thing. A resistor getting hot is harder to explain. But that capacitor does indeed go from the 3.3V rail to ground.

And you guessed right. Let's remove it and see if the short goes away.
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Old 01-22-2019, 06:40 PM   #47
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Yes I'm using my phone for now. It wasn't badcaps, It was my phone not letting me connect with my computer. I'm not very good with a computer, I'm lucky I can get what I'm giving you now. I will place PL12 back on board, and remove that cap. Where do you source a replacement? I have never had to replace something that small before.

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Old 01-22-2019, 08:04 PM   #48
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

You can easily find all those simple components (caps/resistors/etc) at DigiKey or Mouser. They will also be on eBay and such, but with less certainty as to their true manufacturer. Since they are unmarked, you have to trust the seller to identify them honestly.

C550 is a 10uF 6.3V ceramic capacitor in a 0402 (roughly 0.04in x 0.02in or 1mm x 0.5mm) package. Ceramic capacitors also have ratings for temperature low/high/stability. The schematic doesn't say for this one, but "X5R" will be good.
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Old 01-22-2019, 09:44 PM   #49
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I reset PL12, and removed the bad cap. short is no longer there. PL12 now measures on both sides 26.98K ohms. Can you attach the link to what I exactly need from Digikey I have never ordered anything that small, and there site is very confusing.
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Old 01-22-2019, 10:07 PM   #50
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

This one will do nicely.
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Old 01-22-2019, 10:50 PM   #51
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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This one will do nicely.
Ordered, Thank you very much. I'll let you know when it arrives, purchased a few extra.
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Old 01-24-2019, 11:41 AM   #52
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I do believe caps should arrive on Fri or sat at the latest, any tips on placing that small cap on board. I do have Amcap, a microscope pen camera. that will magnify the board. I guess hot air would be best.
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Old 01-24-2019, 04:36 PM   #53
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

For really small components like this, they come right off with a soldering iron to just one side. For larger components, hot air is needed to remove them.

But when it comes time to attach components, hot air is usually not desirable.

I only use hot air to reattach things with pads/balls underneath, like power FETs or BGAs, because then you really do have to heat up the whole component to solder-melting temperatures. It's just more wear and tear on the PCB than is necessary for other things. And tiny components will just want to blow away.

For most components (again, without pads/ball hidden underneath), just clean off the pads with desoldering braid (being extremely extremely careful not to accidentally pull off any neighboring components. Gently hold the new component in place, flat on the pads, and tack down a couple pins with your iron. If there are remaining pins, it is now easy to solder those as well.
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Old 01-24-2019, 06:46 PM   #54
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Quote:
Originally Posted by BlueMidnight View Post
For really small components like this, they come right off with a soldering iron to just one side. For larger components, hot air is needed to remove them.

But when it comes time to attach components, hot air is usually not desirable.

I only use hot air to reattach things with pads/balls underneath, like power FETs or BGAs, because then you really do have to heat up the whole component to solder-melting temperatures. It's just more wear and tear on the PCB than is necessary for other things. And tiny components will just want to blow away.

For most components (again, without pads/ball hidden underneath), just clean off the pads with desoldering braid (being extremely extremely careful not to accidentally pull off any neighboring components. Gently hold the new component in place, flat on the pads, and tack down a couple pins with your iron. If there are remaining pins, it is now easy to solder those as well.
Okay I'll give that a try, I have 10 so if I happen to make a mistake I'll have more to try again.
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Old 01-26-2019, 12:22 AM   #55
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Caps are due in on sat, I will get one on board as you suggested using the iron instead of hot air. Hope I can see that little bugger.
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Old 01-27-2019, 09:32 PM   #56
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Had to order some new soldering iron tips, smallest I had was to big, should arrive on tues.
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Old 01-28-2019, 08:10 PM   #57
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Quote:
Originally Posted by rccrasher65 View Post
Had to order some new soldering iron tips, smallest I had was to big, should arrive on tues.
Well 6 hrs and 2 caps later I finally got that little shit on the board. I hope all this will be successful. I guess we are ready for next step.
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Old 01-28-2019, 08:56 PM   #58
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Those little components do like to jump around all over the place, get sucked up by the iron tip, and other mischief.

At his point, you can try connecting the AC adapter to insure that you get 3.3V on that rail (at PL12).

If you do get 3.3V while the board is plugged in, then you can try turning on the board. The equivalent to a power button press is shorting together pins 3 and 4 of connector CN5 (where the power button cable normally plugs in) for a moment.

The heatsink/fan should be attached for this test.

If the fan spins, then that's at least a good sign. But you will need to install the board in the notebook to test it fully, obviously.
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Old 01-28-2019, 09:47 PM   #59
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Those little caps drove me crazy, doing everything you said, and more. But I finally used hot air turned down to 5 on air flow, finally attached itself. cleaned board. I placed a 1in x3in alum, heat sink on chip and applied power. fan did start to spin. I guess Its time to start pulling apart my laptop to fully test. I will do that and get back to you with all the results. I want to THANK you for the learning experience, I've enjoyed every step of the way, and learned a lot. I d efinately owe you one, and truely appreciate all your help, Thank you again.
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Old 01-29-2019, 12:14 AM   #60
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I installed repaired mother board, and Its working like a charm, Many thanks to Blue Midnight, I cant begin to thank you enough for walking me through my first component level repair. All seems perfect, Its asking for an Operating system just like the replacement did. Ill have to find a good windows 10 operating system, as I have no recovery disk with this lap top. If you happen to know how to get one, please let me know. A friend of mine set this up the last time for me, but he is out of town for over a month on business. Again thank you for all your help, you truely are a master at what you do, many thanks, George
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