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Old 02-10-2019, 08:18 PM   #101
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I agree. PQ5/PQ9 have no signs of a short.

One more thing I can think of is to confirm resistance to ground on +VIN. You can measure that at PR103 (doesn't matter which side since it's only 0.01 ohms), or at the drain of PQ9 instead if you'd prefer.

If that resistance looks good, then it may be time to replace PU20.
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Old 02-10-2019, 08:42 PM   #102
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Originally Posted by BlueMidnight View Post
I agree. PQ5/PQ9 have no signs of a short.

One more thing I can think of is to confirm resistance to ground on +VIN. You can measure that at PR103 (doesn't matter which side since it's only 0.01 ohms), or at the drain of PQ9 instead if you'd prefer.

If that resistance looks good, then it may be time to replace PU20.
PR103-29.05 m ohms Gate of PQ9- 28.42 m ohms
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Old 02-10-2019, 09:03 PM   #103
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I assume that is megaohms and not milliohms. Megaohms is just fine and would mean the next best step is to replace PU20 with another BQ24780S.
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Old 02-10-2019, 09:25 PM   #104
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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I assume that is megaohms and not milliohms. Megaohms is just fine and would mean the next best step is to replace PU20 with another BQ24780S.
Yes mega ohms.
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Old 02-10-2019, 09:41 PM   #105
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

You can get BQ24780S from all the same places you could get the capacitor. The full/long part number may end in "RUYT" or "RUYR", but that's just the quantity it was packaged in when it left the factory, and not any difference in the chips themselves.

You also have one on your other spare board, obviously. But you may prefer to leave well enough alone when it comes to that.
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Old 02-11-2019, 09:21 AM   #106
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Originally Posted by BlueMidnight View Post
You can get BQ24780S from all the same places you could get the capacitor. The full/long part number may end in "RUYT" or "RUYR", but that's just the quantity it was packaged in when it left the factory, and not any difference in the chips themselves.

You also have one on your other spare board, obviously. But you may prefer to leave well enough alone when it comes to that.
I'm, just gonna try and order a few from Digi key, their web page is very confusing, so I'll just call,and tell them what I want. Any tips on changing that chip out, I've done a few of the 144pin HDMI chips, but they are much bigger.

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Old 02-11-2019, 04:45 PM   #107
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

On DigiKey you can search for "BQ24780S" and you'll get several results. Some are entire factory reels or made-to-order reels by DigiKey, or otherwise have a minimum quantity. So you just find the cheapest one they are willing to sell in quantities of 1 or more ("1" in "Minimum Quantity" column), and have in-stock (number available plus the word "Immediate" in "Quantity Available" column).

Which would be this.

Obviously, this part needs to be removed and attached with hot air. You remove it, clean the pads with desoldering braid, and then tin the pads (lightly) with new solder. Then, position the new part, heat it, and wait until the solder melts and the part should self-center on the pads. If you need to reposition it, push it down flat against the board, or break any solder bridges, use a stainless steel implement (like a dental pick).

Flux is essential for this to work well. Good flux means clean metal, which means solder sticks well, which means the surface tension pulls the solder tightly to the metal. This makes a solid joint as well as discourages solder bridges from forming between neighboring pins (extra important when the part has pads underneath the chip that you can't see while soldering, like this one does). And it can't be liquid flux (like the sort that comes in flux pens) that is going to evaporate in a second, or that brown/orange stuff that is solid at room temperature. It should be a decent gel-type flux that will stick around through the whole process. A little rubbing alcohol will clean up the residue afterward.

Louis Rossmann has a bunch of videos on YouTube. The majority of them will have a chip like this being soldered. And they have a good, clear image. He does like to put too much solder on and then clean up the solder blobs after, though. It works for him. But, I prefer to use far less solder so it can be a single step process.
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Old 02-12-2019, 09:26 AM   #108
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Originally Posted by BlueMidnight View Post
On DigiKey you can search for "BQ24780S" and you'll get several results. Some are entire factory reels or made-to-order reels by DigiKey, or otherwise have a minimum quantity. So you just find the cheapest one they are willing to sell in quantities of 1 or more ("1" in "Minimum Quantity" column), and have in-stock (number available plus the word "Immediate" in "Quantity Available" column).

Which would be this.

Obviously, this part needs to be removed and attached with hot air. You remove it, clean the pads with desoldering braid, and then tin the pads (lightly) with new solder. Then, position the new part, heat it, and wait until the solder melts and the part should self-center on the pads. If you need to reposition it, push it down flat against the board, or break any solder bridges, use a stainless steel implement (like a dental pick).

Flux is essential for this to work well. Good flux means clean metal, which means solder sticks well, which means the surface tension pulls the solder tightly to the metal. This makes a solid joint as well as discourages solder bridges from forming between neighboring pins (extra important when the part has pads underneath the chip that you can't see while soldering, like this one does). And it can't be liquid flux (like the sort that comes in flux pens) that is going to evaporate in a second, or that brown/orange stuff that is solid at room temperature. It should be a decent gel-type flux that will stick around through the whole process. A little rubbing alcohol will clean up the residue afterward.

Louis Rossmann has a bunch of videos on YouTube. The majority of them will have a chip like this being soldered. And they have a good, clear image. He does like to put too much solder on and then clean up the solder blobs after, though. It works for him. But, I prefer to use far less solder so it can be a single step process.
Ordered today, that one was same one I chose also, with a little help from Digi key. I will remove PU20, and clean pads, and tin also. I do enjoy watching Louis, someone with his skills and knowledge, would make a killing here in Pgh. I have all the things necessary to replace this chip, hopefully skills will kick in. I have replaced those 144pin Hdmi chips, but they are much bigger. Let ya know what happens, thanks again, enjoy your tutorials.
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Old 02-12-2019, 03:39 PM   #109
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Ordered today, that one was same one I chose also, with a little help from Digi key. I will remove PU20, and clean pads, and tin also. I do enjoy watching Louis, someone with his skills and knowledge, would make a killing here in Pgh. I have all the things necessary to replace this chip, hopefully skills will kick in. I have replaced those 144pin Hdmi chips, but they are much bigger. Let ya know what happens, thanks again, enjoy your tutorials.
Removed PU-20, cleaned pads and re tinned. Now just waiting for new chip to arrive in a few days. Will watch some Vids on placing those kinds of chips.
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Old 02-13-2019, 04:06 AM   #110
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Alright, good luck. The last bit of advise I can give is to inspect the edges of the chip carefully with decent magnification after doing the work. Look for solder bridges and proper centering of the chip before attempting to apply power.
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Old 02-13-2019, 08:30 AM   #111
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Alright, good luck. The last bit of advise I can give is to inspect the edges of the chip carefully with decent magnification after doing the work. Look for solder bridges and proper centering of the chip before attempting to apply power.
Ok, thank you again for all your help, will let you know how it goes.
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Old 02-14-2019, 09:11 PM   #112
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Ok, thank you again for all your help, will let you know how it goes.
New chips have arrived. Will give it my best attempt to replace.
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Old 02-16-2019, 01:31 PM   #113
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Ok, thank you again for all your help, will let you know how it goes.
Well things didn't go so good, while cleaning the old solder from the board, my solder braid must have pulled pin 3 pad off, its not shiny like all the others, a brownish color under scope. I tried to tin, but still the same. I guess board is junk now.I don't know if chip would function without pin 3.
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Old 02-16-2019, 02:08 PM   #114
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I suppose even that scenario is a learning experience in itself. Lifted pads are generally caused by either too high a temperature, too much time dwelling on that pad, and/or too much force being applied to it. It can also be caused by corrosion of the pad, but usually you can tell when an area has been subjected to that.

But all is not lost. It can still be repaired.

If you can get the rest of the pins soldered successfully, then a thin wire can be run directly from pin 3 to where it needs to go.

You can pre-tin one end of the wire, and then stuff it under pin 3 of the chip and heat the solder. The other end of the wire goes to the right side of the resistor indicated in photo #8.
Attached Images
File Type: jpg 8.jpg (68.1 KB, 6 views)
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Old 02-16-2019, 05:38 PM   #115
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Originally Posted by BlueMidnight View Post
I suppose even that scenario is a learning experience in itself. Lifted pads are generally caused by either too high a temperature, too much time dwelling on that pad, and/or too much force being applied to it. It can also be caused by corrosion of the pad, but usually you can tell when an area has been subjected to that.

But all is not lost. It can still be repaired.

If you can get the rest of the pins soldered successfully, then a thin wire can be run directly from pin 3 to where it needs to go.

You can pre-tin one end of the wire, and then stuff it under pin 3 of the chip and heat the solder. The other end of the wire goes to the right side of the resistor indicated in photo #8.
I checked my iron temp 480C. It was my fault completely, I got braid to stick, wasn't gentle with it, pulled a little to hard, surprised more didn't come off. Good thing I only payed $10.00 for board. I will try to repair this, What size wire you recommend? I definately don't have anything that small. You want me to put that wire on before chip is set, or after chip is set.Either way its gonna be nearly impossible.That's why I'm here to learn from my mistakes.

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Old 02-16-2019, 06:55 PM   #116
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

After the chip is in place, you can attempt to solder the wire by using the iron with a thin tip.

The diameter of the wire isn't critical from an electrical standpoint. It will draw very little current.

The width of the pins on the chip are 0.2 mm, which corresponds to roughly 32 AWG. Going slightly larger may be possible, but going too large risks creating solder bridges with the neighboring pins. There is only a 0.1 mm gap between the pins. I'd say don't go any larger than 28 AWG, but smaller may be necessary.

There is a slightly different technique you could attempt if you wish. If the trace going to pin 3 is still there, it is possible to scrape off the green solder mask covering the trace with the point of a knife until you see bare copper (being careful not to remove any solder mask covering neighboring traces). Then, you can solder a short bit of bare wire between pin 3 and the trace. So basically, this bit of wire would be laying directly on top of the trace (the more of the trace, the better), pushed up against the side of the chip, and covered completely with solder along its length.

Which technique is easier probably comes down to personal taste. But, little bits of wire like that tend to get sucked up into the solder on the iron tip the same way other small components do. So it might get frustrating trying to position it if you're not used to that. It is a more robust repair though, since soldering a long wire directly to the chip pin doesn't give it as much surface area to hold onto. Plus it can break off if it flexes back and forth too much.
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Old 02-16-2019, 11:08 PM   #117
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I'm pretty sure the trace is intact, and just the pad was pulled off. I will try to cut away the solder mask on top to expose the copper, that would be the best for me I think, either way, I don't think I'll be successful in getting the board to work again, just don't have the skills to make a repair like this, I can barely see, pins as small as those are. but I will give it my best shot. Still a great learning experience, and thanks for taking time out of your day to give a noob a hand.
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Old 02-18-2019, 04:15 PM   #118
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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I'm pretty sure the trace is intact, and just the pad was pulled off. I will try to cut away the solder mask on top to expose the copper, that would be the best for me I think, either way, I don't think I'll be successful in getting the board to work again, just don't have the skills to make a repair like this, I can barely see, pins as small as those are. but I will give it my best shot. Still a great learning experience, and thanks for taking time out of your day to give a noob a hand.
Donor board now, Thanks BlueMidnight for all your help!That kind of repair way beyond my skill set, just too small!
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Old 02-18-2019, 04:39 PM   #119
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Beyond your skill set.. for now :P Even a failed attempt is still a learning experience. Maybe next time.
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Old 02-19-2019, 01:00 PM   #120
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Default Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

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Beyond your skill set.. for now :P Even a failed attempt is still a learning experience. Maybe next time.
Thank you Sir for all your time and Patience, 2 out of 3 isn't bad though, couldn't have done it without your help, Thanks again!
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