Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

You can open the RAR file with 7-Zip.

I would consider soldering work to be the last resort. And actually, there's one more thing to try. The most neat and orderly explanation I can think of would be if PR70 were shorted. It's not a common failure mode for resistors, but it can happen. It's an even nicer explanation if the board is turning on PQ8. That would create the path to ground we are looking for, and it would disappear when the board is unpowered.

Let's test this hypothesis (See attached pic #13):

- With the board unpowered, test the resistance of PR70. It's supposed to be 13k ohms.

- With power connected to the board, measure the voltage on the pins of PQ8.

Resistence on PR70 is 12.99 to 13.03K ohms I checked this a few times. With power connected to board PQ8 pin1-0.0mv pin2-0.9mv pin3-0.3mv

[BlueMidnight]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

You can open the RAR file with 7-Zip.

I would consider soldering work to be the last resort. And actually, there's one more thing to try. The most neat and orderly explanation I can think of would be if PR70 were shorted. It's not a common failure mode for resistors, but it can happen. It's an even nicer explanation if the board is turning on PQ8. That would create the path to ground we are looking for, and it would disappear when the board is unpowered.

Let's test this hypothesis (See attached pic #13):

- With the board unpowered, test the resistance of PR70. It's supposed to be 13k ohms.

- With power connected to the board, measure the voltage on the pins of PQ8.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Okay, doing the math for the multiple paths of significance from +VA to ground and back up to LIMIT_SIGNAL, I get a value of 190k. That seems to check out. And come to think of it, we could explain the 1.749k resistance reading with the power supply connected if it has a discharge resistor on the output of perhaps 1.8k-2k.

But the near zero voltage reading on LIMIT_SIGNAL still doesn't make sense unless there is a short. It would have to be the sort that hides unless it is in the powered condition.

I'd probably double-check for corrosion and such -- including around the area in pic #12. If nothing found, then it's possible to inject up to 5V at LIMIT_SIGNAL (at CN11) with a current-limited supply and see what happens. Alternatively, it's possible to desolder PR158 and PR70 to narrow things down.

Ok , i'll check for corrosion around components in pic 12 . I'll clean board as well. A pic of PR158 and PR70 would be helpful. So I should desolder them first, befor adding 5V at CN11 pin 6?, this maybe getting beyond my skill set, but if I mess it up oh well, always another board to try. Can't learn without trying. Give it my best shot. I still don't know how to open that board view file. It's a rar file. Can that file be sent as a link, so that I can just open it?

[BlueMidnight]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Okay, doing the math for the multiple paths of significance from +VA to ground and back up to LIMIT_SIGNAL, I get a value of 190k. That seems to check out. And come to think of it, we could explain the 1.749k resistance reading with the power supply connected if it has a discharge resistor on the output of perhaps 1.8k-2k.

But the near zero voltage reading on LIMIT_SIGNAL still doesn't make sense unless there is a short. It would have to be the sort that hides unless it is in the powered condition.

I'd probably double-check for corrosion and such -- including around the area in pic #12. If nothing found, then it's possible to inject up to 5V at LIMIT_SIGNAL (at CN11) with a current-limited supply and see what happens. Alternatively, it's possible to desolder PR158 and PR70 to narrow things down.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

no DC jack connected +VA to limit signal 187.3 K ohms, reverse 188.4 K ohms. In diode mode OL, reverse same OL Board #2 187.1 K ohms, reverse 188.6 K ohms In diode mode OL, reverse same OL

going to clean up those pads today. I think I can get that cap from my donor board.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

The component near pin 1 of CN11 is PC164, a 0402 size 0.1uF 25V capacitor. It's used for input power filtering. While it should be there, it shouldn't prevent the board from working.

The +VA to LIMIT_SIGNAL resistance looks interesting. What is the reading without the DC jack connected? Is it the same in both polarities? What do these measurements look like on the second board?

no DC jack connected +VA to limit signal 187.3 K ohms, reverse 188.4 K ohms. In diode mode OL, reverse same OL Board #2 187.1 K ohms, reverse 188.6 K ohms In diode mode OL, reverse same OL

[BlueMidnight]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

The component near pin 1 of CN11 is PC164, a 0402 size 0.1uF 25V capacitor. It's used for input power filtering. While it should be there, it shouldn't prevent the board from working.

The +VA to LIMIT_SIGNAL resistance looks interesting. What is the reading without the DC jack connected? Is it the same in both polarities? What do these measurements look like on the second board?

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I'm good, thank you. Just a busy weekend. Didn't have a chance until now to fully investigate the next steps.

Okay, so that is a very curious result. But, of course, sometimes the less likely thing is what happens.

So we are left in the same position as before. Either the resistance from pin 6 to the positive connection is too high, or the resistance from pin 6 to ground is too low.

First, I'd like to just verify how many ohms the ID resistor is inside the new power supply. With the new power supply and DC jack plugged into each other but not plugged into anything else, what is the resistance between the pins 1 and 6 (red and brown wires)?

It should be ~500k for a 45W power supply, 390k for 60W, or 440k for 90W.

You've already checked the resistance between CN11 pin 6 and ground and it was fine. Let's try testing it a couple additional ways.

First, connect the power supply and DC jack to the motherboard. Do not plug the power supply into the power outlet. Measure the resistance between +VA and LIMIT_SIGNAL as indicated in attached pic #12. This is the same as measuring the red and brown wires, but also will test the connection through CN11. I've marked some other stuff on the pic, but ignore that for now.

Second, try measuring between LIMIT_SIGNAL and ground using diode mode in the meter just to see if the readings are any more interesting. Try both polarities of the probes.

Ok ,did all measurements over, first the Id resistor on DC jack and power supply is 333.3 K .ohms next, CN11 pin6 to ground is 62.0 K ohms Next, +VA and limit signal, 1.749 K ohms in pic#12 next in diode mode OL with probes switched. same either way. Also looked at board under scope. Component next to CN11 pin 1 white dot just fell off. It was just hanging on. I do blieve its a diode. pads look ok. ITS TINY, can hardly see it.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I was just looking over the board with the camera, and discovered that the component next to CN11 nest to pin one, and white dot on board, has lifted not connected to outside pad towards the edge of the board. I'm assuming that is a diode. I'll get those measurements this evening, thanks BlueMidnight!

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I will try what you suggest this evening and post results. Its just confusing that on the second board all my new parts work, even the other parts, could there be a problem with the traces to the pins on the connector itself. I will get to it, thanks again.

[BlueMidnight]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I'm good, thank you. Just a busy weekend. Didn't have a chance until now to fully investigate the next steps.

Okay, so that is a very curious result. But, of course, sometimes the less likely thing is what happens.

So we are left in the same position as before. Either the resistance from pin 6 to the positive connection is too high, or the resistance from pin 6 to ground is too low.

First, I'd like to just verify how many ohms the ID resistor is inside the new power supply. With the new power supply and DC jack plugged into each other but not plugged into anything else, what is the resistance between the pins 1 and 6 (red and brown wires)?

It should be ~500k for a 45W power supply, 390k for 60W, or 440k for 90W.

You've already checked the resistance between CN11 pin 6 and ground and it was fine. Let's try testing it a couple additional ways.

First, connect the power supply and DC jack to the motherboard. Do not plug the power supply into the power outlet. Measure the resistance between +VA and LIMIT_SIGNAL as indicated in attached pic #12. This is the same as measuring the red and brown wires, but also will test the connection through CN11. I've marked some other stuff on the pic, but ignore that for now.

Second, try measuring between LIMIT_SIGNAL and ground using diode mode in the meter just to see if the readings are any more interesting. Try both polarities of the probes.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

No power on pin 6, with new power supply and DC jack. There has to be something wrong with the connector itself. I checked under microscope to see if I can find any burnt trace or pin, nothing! all looks good very minimal corrosion. I'm just confused at this point. Is there anything that protects that connector that could be bad? On board 2, I managed to get fan to spin for a second or two. the white charge light on the DC jack flashed once and shut off.

Hope all is well with you, haven't heard from you in a few days, stay safe!

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

New DC jack and power supply arrived.

No power on pin 6, with new power supply and DC jack. There has to be something wrong with the connector itself. I checked under microscope to see if I can find any burnt trace or pin, nothing! all looks good very minimal corrosion. I'm just confused at this point. Is there anything that protects that connector that could be bad? On board 2, I managed to get fan to spin for a second or two. the white charge light on the DC jack flashed once and shut off.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

New DC jack and power supply arrived.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Problem solved, loose keyboard ribbon. I'm not going to disassemble laptop. parts should be in on 9th. If we can look into the other board while we wait for new parts, that would be great.

I was doing some voltages measurements on board #2 the one with the voltages present, using the dc jack that showed good voltages, and my power supply. I checked CN11 I get the 5.04V on pin 6 that we are looking for on board 1. i'm just not understanding whats going on with board 1 CN11. If DCjack and power supply work on board 2, then why not board 1. Can there actually be a problem with the actual connector(CN11) itself, like a burned trace we can't see.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Yes, you can use the DC jack from the laptop if you disassemble it.

Flickering problems like that are usually the screen itself or the cable connecting it to the motherboard. If movement leads to flicker, then you can gently press/flex the various parts to search for bad connections or broken wires. It might be necessary to disassemble the top cover (i.e. the part of the case that surrounds the LCD itself) to properly check all areas.

Yes, that component is PU20. Location is in the pic in this post.

Problem solved, loose keyboard ribbon. I'm not going to disassemble laptop. parts should be in on 9th. If we can look into the other board while we wait for new parts, that would be great.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

I'll disassemble and see what I can find. I'll get those measurement on PU20in a day or so.

[BlueMidnight]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Yes, you can use the DC jack from the laptop if you disassemble it.

Flickering problems like that are usually the screen itself or the cable connecting it to the motherboard. If movement leads to flicker, then you can gently press/flex the various parts to search for bad connections or broken wires. It might be necessary to disassemble the top cover (i.e. the part of the case that surrounds the LCD itself) to properly check all areas.

Yes, that component is PU20. Location is in the pic in this post.

[rccrasher65]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

Can I use the DC jack from the laptop, as I'm going to disassemble, to see what causing the flickering, has to be something loose. It flickers now even when I touch the case. I can squeeze it and stop the flickering.Can you also show me PU 20. I hope it's not that component I jacked up on my parts board, trying to remove, lifted the pads. I think it is though.

[BlueMidnight]

Re: Hp Probook 455 G3 DAX73AMB6E1 blinking charge light, not turning on

For the other boards... as a general rule, problems earlier in the power sequence are easier to find and fix. So the lowest hanging fruit is probably the one with no voltage present on the power rails. And for that one, the next step is to measure the voltage on the pins of PU20.

Best to wait for the new parts first, though.