Dell Inspiron 15 5570 Plugged in not charging

[Eniaro]

Dell 5570 - LA-F115P

I found the Schematic here
There may be errors in how I interpret the schematics, correct me if I'm wrong, please. I'm learning to read schematics [at least I think I am]

LA-F115P CAL50 DAL10 REV 1.0 (A00) Dell Inspiron 15 5570 schematic diagram
https://www.badcaps.net/forum/attach...0&d=1602584738

Found the problem







According to the Schematic (Page 53) PD1 part number is TVNST52302AB0_SOT523-3




Googling the part number leads me to Mouser with parts that have the same package size. Or other schematics that have the same part.

Where do I get, and know if I'm getting the right part?

Is it a common/standard part on Dell laptops if so can I find it on another dell laptop, I have a box full of older ones made in 2009-2012?

[mon2]

Re: Dell Inspiron 15 5570 Plugged in not charging

Hi. The referenced part, PD1 is a transient TVS diode. This component protects the attached voltage rail from being damaged from sudden bursts of energy caused by static discharge or similar events. This part will clamp the energy to ground to protect further damage. Often such parts are sacrificial in that they will die to protect the rail.

On this note, they are not immediately required for the design to work but a damaged part could impact the operation of your logic board.

For now, you can remove this part off the PCB. Just have to be careful about static on your body.

The part can be replaced by many similar devices in the SOT-523 package such as the following from Littlefuse:

https://cdn.badcaps-static.com/pdfs/...fa7fe10248.pdf

Same pinout and footprint as the original from INPAQ (Taiwan).

It should be possible to source this part from Mouser, Digikey or Arrow Electronics. Not familiar with Dell boards but check near the USB connectors which may offer a similar part to protect the D+ / D- USB 2.0 interface.

[mcplslg123]

Re: Dell Inspiron 15 5570 Plugged in not charging

Removing PD1 will let the mb to charge perfectly but protection is gone. Quite a common problem on LA-F115P mb.

[Eniaro]

Re: Dell Inspiron 15 5570 Plugged in not charging

Replaced PD1 and PC worked perfectly. Thank you

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

Thank you for this! I only found one YouTube video that even mentions which component on the motherboard could fail when the sense/ID line has overvoltage. And that video was in a language I could not understand. He just flipped the motherboard over and pointed at the TVS diode package.

Since only half of PD1 is connected, I wonder if I could remove the leg from the shorted diode and run a wire from the NC pin. That would remove the shorted diode from the circuit, and allow the sense signal to use the unused half of the TVS diode package?

I know, I should just replace the whole package. I'm just looking for the Easy button.

Thanks again!
Dana Repouille

[mon2]

Re: Dell Inspiron 15 5570 Plugged in not charging

Best to replace the tvs diode since a transient took the part out. Very possible that the other half was impacted by the transient.

What is the exact part # ? Digikey or Mouser should have the part.

For now, you could hot air and remove the damaged part off the logic board but note that the esd protection is lost.

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

I have donor motherboards for the Inspiron 5570. The schematic indicates that PD1, PD5, and PD6 are all TVNST52302AB0_SOT523-3. PD1 is connected to the charger sense pin, while PD5 and PD6 are connected to the battery data and clock pins. That makes it easier to find cheap replacement parts. Thanks for the schematic!

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

Hi. The referenced part, PD1 is a transient TVS diode.
Not familiar with Dell boards but check near the USB connectors which may offer a similar part to protect the D+ / D- USB 2.0 interface.

The Dell Inspiron I/O daughterboard (for USB 2.0, SD card reader, and CR2032 battery) is LS-F111P. It appears to have a similar TVS diode labeled DI1 next to the USB port. However, it seems to be a different part number than the three TVS diodes on the motherboard.

Is a schematic for the LS-F111P available for download?

[mon2]

Re: Dell Inspiron 15 5570 Plugged in not charging

Attached.

L30ESDL5V0C3-2_SOT23-3

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

Thank you. Even though the TVS diode on the daughterboard is in the same SOT23-3 package, it has a different part number than PD1, PD5, and PD6 on the motherboard. I assume it has different thresholds, so it would not be safe to use it to replace the other three TVS diodes. That may be because the USB port uses 5V, while the data lines on the motherboard use 3.3V. Just guessing here.

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

Oh wait. The three packages on the motherboard are SOT523-3, but the package on the daughterboard is SOT23-3. It's easy to miss that difference!

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

There appear to be four TVNST52302AB0_SOT523-3 packages on the motherboard. In addition to PD1, PD5, and PD6, I think EU4012 is the same package type. It appears to be connected to Pin 2 of JFP1, the fingerprint reader connection. However, when I look for it on LA-F115P TOP.pdf, it appears in the middle of the board, nowhere near the fingerprint reader connector. Now I need to examine the motherboard under a scope to find EU4012.

I'm just looking for all the spare TVS diodes that I can harvest from donor boards to replace blown PD1, since it seems to be a common failure point (by design).

[mon2]

Re: Dell Inspiron 15 5570 Plugged in not charging

A compatible ESD TVS diode should be available from Digikey / Mouser / Arrow.

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

It looks like EU2701 is near JFP1, so I don't know why the schematic shows EU4012 connected to JFP1. Confusing.

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

Nope. EU2701 and EU4012 are both AZC199-02SPR7G_SOT23-3, which do not match PD1, PD5, and PD6. Oh well. There are plenty of donor boards available, especially the ones with 7th Gen Intel processors that nobody wants.

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

Agreed. Since we don't know the specifications of the original part, how do we know which model of TVS diode to order?

It looks like they cost about 50 cents each for a lot of 100, so about $50 for 100? It seems like someone on eBay could make money buying 3,000 of these, and cutting them into smaller strips. If they list them on eBay as Dell Inspiron TVS diodes, I would buy them.

[Eniaro]

Re: Dell Inspiron 15 5570 Plugged in not charging

Agreed. Since we don't know the specifications of the original part, how do we know which model of TVS diode to order?

It looks like they cost about 50 cents each for a lot of 100, so about $50 for 100? It seems like someone on eBay could make money buying 3,000 of these, and cutting them into smaller strips. If they list them on eBay as Dell Inspiron TVS diodes, I would buy them.

I've used Little Fuse SP0502BAHTG in a previous repair in 2021. The laptop is still going. It was recommended by Mon2 @ the start of this thread.

So this should be written as 2.168K = ~2.2k or ~2K2 ohms.

Noted for future I did not know this

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

I've used Little Fuse SP0502BAHTG in a previous repair in 2021. The laptop is still going. It was recommended by Mon2 @ the start of this thread.

I appreciate the link, and may order some from Mouser.

I found two listings for SP0502BAHTG on eBay. Oddly enough, both listings state this is a "SP0502BAHTG SOT-23 Littelfuse Diodes - TVS" rather than a SOT523-3. I often worry that eBay listings are inaccurate, especially when accuracy matters the most.

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

This website was started because of Bad Capacitors (and has evolved over the years...) I'd replace the tvs diodes with new ones because tvs diodes might be the new bad caps

I agree with that, especially since PD1 is connected to the center pin of the charger, and is routinely abused each time the charger is connected. My theory was that I could harvest PD5 and PD6 from the battery's data and clock lines of donor boards, and use them to replace PD1.

I just now removed a blown PD1 from a motherboard, and it worked (charged the battery) perfectly! However, the SOT523-3 package is so darn tiny that I can't imagine how I am going to install a replacement onto those tiny pads.

I have a digital camera with zoom, as well as a 5X magnifying lens, but performing soldering miracles at that level is just insane. I don't know why the companies that make these magnifiers mount them onto an "adjustable arm" that shakes with the work surface.

And not to mention that when I removed the blown PD1 diode package, I noticed that two of the three legs came off. That may have happened because the shell was damaged and structurally unsound, or maybe because my tweezer hand was a bit shaky.

[dana.repouille]

Re: Dell Inspiron 15 5570 Plugged in not charging

Well, I was close!

My donor board had a good PQ1 and a blown PD1. I removed the blown PD1, and the board recognized the Dell charger again. However, when I removed the blown PD1, it ripped out the pad near PL3. That is OK -- it's a donor board.

So I harvested PQ1, PD5, and PD6 from the donor board to use on my "target" board.

My "target" board had a blown PQ1, so I suspected PD1 was also questionable, since it did not protect PQ1 as it should have. I removed PQ1 and PD1 from the target board. Since PQ1 was so badly scorched, it ripped up half the pad under one of its legs. There was enough of the pad left behind to use, so I transplanted PQ1 and PD5 from the donor board onto the target board in the PQ1 and PD1 locations.

The target board still does not recognize a Dell charger. I suspect either PR1 or PQ2 are also damaged. After all this microscopic SMD work, I need a break. So I may try to transplant PR1 and/or PQ2 after my eyes have recovered. Better yet, I think I will switch to transplanting USB 3 ports from my donor board to others that need them.