Latitude 5480 No Power/Charging, ID pin on motherboard shows 19V

[TheoConnor]

Battery disconnected.

1. Charger connected
- 19V on both, red cables and ID pin
2. Charger disconnected
- red cable and ID pin NOT shorted - OL
3. Removed those cable, DC socket
- wired NOT shorted
4. Checked charger directly
- 19V, ID pin - 0.04V
5. Connected charger to this cable, but NOT
connected to the board
- all fine
6. Put back in a place
- ID pin show 19V

Any idea ? How to proceed, what to check next ?

[rogfanther]

Is this a correct Dell charger ? Original ?

With the charger connected to the cable, but with both cable NOT connected to motherboard, and charger not connected to power, measure resistance between the pins on the cable.

[sourcebf]

Battery disconnected.

1. Charger connected
- 19V on both, red cables and ID pin
2. Charger disconnected
- red cable and ID pin NOT shorted - OL
3. Removed those cable, DC socket
- wired NOT shorted
4. Checked charger directly
- 19V, ID pin - 0.04V
5. Connected charger to this cable, but NOT
connected to the board
- all fine
6. Put back in a place
- ID pin show 19V

Any idea ? How to proceed, what to check next ?

try to remove this component and try the board without it, please add your board ID number

[sourcebf]

and check PU2 Vout if you have 3.3 v at the output (it is applicable for LA-E082P motherboard number)

[reformatt]

Replace the DC jack. You should only have 3.3V max on the PSID pin.

[TheoConnor]

Is this a correct Dell charger ? Original ?

With the charger connected to the cable, but with both cable NOT connected to motherboard, and charger not connected to power, measure resistance between the pins on the cable.

Yes, original Dell 65W charger, and I have two identical, and both works, tested with multimeter and charging other Latitude laptops - recognized, and works. No resistance between ID and Plus.

[TheoConnor]

try to remove this component and try the board without it, please add your board ID number

Can't remove - have no tools yet, but will measure later.

Dell Latitude 5480
REV:A01
PWB:0M6OW
CDM70 LA-E081P
Rev:2.0( A01 )
2017-06-29

[TheoConnor]

Replace the DC jack. You should only have 3.3V max on the PSID pin.

DC jack tested while disconnected from the board - measured fine.

[TheoConnor]

Additional information:

Original Dell 65W PSU

• bought separately, tested on this and other laptop - works
• was powering this laptop, and other
• also used 2nd identical PSU on this laptop - worked before

Battery

• Fully charged in excellent condition, new
• In bios battery setting was set to AC Primarily
• Power was connected constantly for the two days before I discovered 'No Power' on Power button push

When I plug battery back (charger not connected), and
then push power button

• Power Button lights up
• CPU starts to get warm
• fan not spinning, no screen, no keyboard light
• But it's not responsive, holding Power button will not power off, have to remove battery
• But when attach charger, this above will not happen

Front LED was always lighted up for 2 second when I was attaching charger, now
it's nothing.

I tried:

• Opened, removed battery, tried switching RAM, removed SSD, unplugging coin-battery - no change
• Laptop was sitting in "AC primarily" battery mode connected, and in hibernation, so no outside factors

[reformatt]

The only way PSID can get 19V on it is via a collapsed DC jack centre pin, shorting the inner and outer rings together. PD4 usually goes short with 19V; anything above 5V or so will turn on PQ3 to remove gate drive from PQ2, protecting the EC from excessive voltage. 19V can destroy the one wire chip in the charger though. That said, missing PSID won't prevent a laptop from starting, just throttle the CPU and battery wont charge.

Proper way to diagnose this is to connect charger only, ignore PSID for the moment. Do you have +3V on the power switch? Does it drop to 0V when pressed? What voltages are present on the board when it starts up? All up to CPU Vcore? Assuming Vcore is present, use an external DC supply and measure input current with and without RAM installed.

People can only help if you give accurate measurements.

[TheoConnor]

The only way PSID can get 19V on it is via a collapsed DC jack centre pin, shorting the inner and outer rings together. PD4 usually goes short with 19V; anything above 5V or so will turn on PQ3 to remove gate drive from PQ2, protecting the EC from excessive voltage. 19V can destroy the one wire chip in the charger though. That said, missing PSID won't prevent a laptop from starting, just throttle the CPU and battery wont charge.

Proper way to diagnose this is to connect charger only, ignore PSID for the moment. Do you have +3V on the power switch? Does it drop to 0V when pressed? What voltages are present on the board when it starts up? All up to CPU Vcore? Assuming Vcore is present, use an external DC supply and measure input current with and without RAM installed.

People can only help if you give accurate measurements.

Ok, I will try to provide as much as possible measurements.
To eliminate possibility of faluty DC jack, or/and charger, I did this:

1. Remove DC wire-connector from the board
2. Attach Battery
3. Try to power on

Result:
- Power button lights up
- CPU slowly gets warm
- nothing on a screen, no keyboard backlite, no sound warnings, nothing
- not responding - disconnected battery





Next I will try to isolate charger ID pin, disconnect battery (I keep it disconnected now whole the time), and make all important measurements, and for
that I will need to take board out, will update on results.

[TheoConnor]

Update:

• took out the motherboard for inspection
• took some pictures, and did not notice anything wrong
• put all back, and started to review picture and notice something
• I don't know where to start with measurements, please guide me
• I don't have tools for this micro-soldering, like hot air station yet, but I am will be able to take measurements

thanks

[TheoConnor]

So this is USB-C right to DC In connector, that may explain a few things, just guessing here.