Dell Latitude 7430 - LA-L581P: not powering on, not charging.

[djtaotao]

Hello guys, I need some help for troubleshoot my personal laptop. It's my first attempt to repair a laptop, I have good soldering skills and basic electronics knowledge.

Dell Latitude 7430 - not powering on, not charging.
The USB charger is negotiating the voltage and the USB meter shows 19.98V and 0.08A on both ports.
When I plug in the charger the led on the power button lights up and stays on for 30s, turns off for 1s and turns on again for 30s and so on.

The main power rail is done by ISL9538, without battery I have +8.6V and with the battery plugged in I have constant +17.2V on it.
The disconnected battery shows me 16.2V.
With battery connected to MB I tried to inject some voltage to the battery connector but is taking no current.

I changed the charging IC ISL9538 and the associated boost dual mosfets FDPC5030SG with no results, I have the same behaviour.

I have attached a picture of a reference schematic for the charging circuit.

3.3V and 5V are present.

Thank you for any advice!

[mon2]

Voltage to ground check on:

ACOK
ACIN

[djtaotao]

AKOK = 3V
ACIN = 3.8V

[mon2]

These are good measurements. ACOK is at a logic '1' since the ACIN > threshold voltage from the power adapter so the charger IC likes the power adapter.

What are the voltage to ground measurements for the DCin mosfets? What is the gate voltage? It must be higher than the voltage being passed between source / drain pins to enable so should be ~25 volts which is supplied by the charger IC.

[djtaotao]

I assume you're referring to the 1st and 2nd mosfets and I think they are opened by the PD controllers, there are 4 mosfets, 2 for each PD and they are P-channel, the voltage on their gates is 1.8V, and the voltage after them is 19.9V.

[Bill F]

I believe you may have a bad bios. I had two boards behave like that. A new clean bios fixed them.

[djtaotao]

I believe so. I tried to "cook" a clean one based on yt tutorials but I failed. The CSME FIT tool is giving me some decompress error messages.

[mon2]

Post your request for a working bios for this logic board in the dedicated bios forum. See above.

[santoslao]

Hello guys, I need some help for troubleshoot my personal laptop. It's my first attempt to repair a laptop, I have good soldering skills and basic electronics knowledge.

Dell Latitude 7430 - not powering on, not charging.
The USB charger is negotiating the voltage and the USB meter shows 19.98V and 0.08A on both ports.
When I plug in the charger the led on the power button lights up and stays on for 30s, turns off for 1s and turns on again for 30s and so on.

The main power rail is done by ISL9538, without battery I have +8.6V and with the battery plugged in I have constant +17.2V on it.
The disconnected battery shows me 16.2V.
With battery connected to MB I tried to inject some voltage to the battery connector but is taking no current.

I changed the charging IC ISL9538 and the associated boost dual mosfets FDPC5030SG with no results, I have the same behaviour.

I have attached a picture of a reference schematic for the charging circuit.

3.3V and 5V are present.

Thank you for any advice!

Would it be possible for you to provide the electrical diagram for this board? I would be grateful!

[SMDFlea]

Would it be possible for you to provide the electrical diagram for this board? I would be grateful!

Read again "I have attached a picture of a reference schematic for the charging circuit." . There is no schematic available but a boardview has recently been released.It is on some paid sites.If you post your request in the thread where you`ve already asked for the schematic someone might post it,if you`re lucky. https://www.badcaps.net/forum/troubl...581p-schematic .Or you could buy it yourself and share it

[djtaotao]

Would it be possible for you to provide the electrical diagram for this board? I would be grateful!

Unfortunately I don't have it. The schematic I posted it above is for the LA-K371P board, most likely the previous Latitude version. That schematic is for free to download on the internet.