LA-F115P +19VB = 13.6v instead of 19v

[koby058]

Re: LA-F115P +19VB = 13.6v instead of 19v

Nice to know that the unit is working. Try with another dell original known good adapter.
If adapter is still not recognised, you have alikely fault in PS_ID circuit which is very simple to solve. Check whether PS_ID is present on pin36 of SIO and 33 Ohms resistor is intact or not.

I have checked resistance is 33ohm and i have 3.3v on pin36 but still it complains it cannot recognize adapter

Since it is not a bios issue i have reflashed the original BIN that i have backed up before changing bios still not recognizing the adapter

what else it could be ?

[mon2]

Re: LA-F115P +19VB = 13.6v instead of 19v

Measure the voltage to ground on both sides of PL3 with the power adapter connected.

Then remove PL3 for a quick test. Measure the voltage at PL3 again and post all readings.

[koby058]

Re: LA-F115P +19VB = 13.6v instead of 19v

voltage is 3.3v when connected

is removing it and measure == measure on pin 3 on the charging port when it is disconnected from board?

if yes then voltage on pin 3 of charging port is 0v


I am asking since it will take me time to remove

[mon2]

Re: LA-F115P +19VB = 13.6v instead of 19v

Hmm. You should have some voltage on pin # 3 of the charging port side since this is the voltage that the local EC controller will sample (Analog to Digital conversion) to determine the power rating of the adapter.

Can you check if the voltage is present if you float the power connector in the air ? This same power adapter functions to power other laptops OK ?

If the voltage is present if you DO NOT connect to this board, then check the connections of the DC in power connector. Also, with NO power, check the resistance to ground of this same pin #3 on the charging port. Perhaps some short to ground that is halting this PS_ID from working.

[mcplslg123]

Re: LA-F115P +19VB = 13.6v instead of 19v

Besideds@mon2's suggestion, check whether ACOK is pulled low.

[koby058]

SOLVED: LA-F115P +19VB = 13.6v instead of 19v

Hi, thank you all for your help.

It was a great learning experience, I have brought (laptop tests was at home) a new charger and new charging port (eventually was not used), and the laptop works ok now.

I am really appreciate the time and effort invested here by you

Thanks

[mferna14]

Re: LA-F115P +19VB = 13.6v instead of 19v

I have identical problem in this model. No AC power adapter detected. PSID is fine, get 3.3 volts, ACOK is fine. But I still cannot understand the logic of 13.5V on the main 19v rail. Why do the MFG. want voltage to drop with this buck converter. Can someone pls. explain me this logic???

[mcplslg123]

Re: LA-F115P +19VB = 13.6v instead of 19v

Read about NVDC technology in charging circuit and it'll be clear to you why 13.5V as main rail is correct.

[mferna14]

Re: LA-F115P +19VB = 13.6v instead of 19v

Thanks for the info.... Now inform me why is the laptop not working on AC power. But at time when I remove the motherboard & turn it on Stand alone, it works perfectly on AC power, the moment I attach the battery terminal, NO AC POWER DETECTED. Can you please help me in this. Thanks

[mon2]

Re: LA-F115P +19VB = 13.6v instead of 19v

Is the adapter being detected ok if the battery is removed?

If not...

Check the continuity of the PS_ID line to the actual connector contact on the DC power jack.

If it is ok, measure the voltage to ground of the protection mosfet (source / drain / gate).

Post each measurement.

Sounds like you have a leaky 2nd DCin mosfet if the battery and AC adapter cannot coexist.

Remove all power -> meter in resistance mode -> check the resistance across the 2nd DCin mosfet.

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement.

[mferna14]

Re: LA-F115P +19VB = 13.6v instead of 19v

Thanks @mon2 for the quick response. I will do this tomorrow, as I close right now & will come fresh with all these troubleshooting methods. Will surely inform you tomorrow.

[mferna14]

Re: LA-F115P +19VB = 13.6v instead of 19v

mon2., PSID continuity is perfect. Right now I want to inform you about the intial two MOSFET (both PNP) PQ3 & PQ4. 19v enters the source of PQ3. Now accourding to the schematics there is a voltage dividers on the Gate (1Mx1M). Out here I am getting 18.1v, which is not right, according to the divider formula, the voltage should be around 9.79 volts. So something is wrong in the initial stages. Now except for 19v ponits I am not getting any voltages on the board because PQ3 is not by passing the 19v to PQ4 & the board. So now pls. guide me. I have to check PQ3 gate & correct these voltages. I shorted/soldered a wire to see any difference, but nothing, still does not turn on with AC power. Both MOSFET are ok. Not getting +3.3V_ADP_DCIN & this is generated through PU1 RT9069-33GB_SOT23-5, Input 19v pin 1 is fine, EN pin 4 is ok, output pin 5 varies, & I observe it now, it is getting hot, poured alcohol on it, just sparked ^_^. Is there any replacement for this chip RT9069-33GB_SOT23-5 ??? Thanks

[mon2]

Re: LA-F115P +19VB = 13.6v instead of 19v

Remove all power and measure the resistance to ground at the output of this LDO regulator that is getting hot.

Replacements are available from Digikey:

https://www.digikey.ca/en/products/d...9-33GB/5270908

[mferna14]

Re: LA-F115P +19VB = 13.6v instead of 19v

Thanks., will do this what you told me.

[mcplslg123]

Re: LA-F115P +19VB = 13.6v instead of 19v

Working on a dell G3 gaming laptop-works on battery but dont work on adapter. After taking the board out, RT9069-33GB is blown. Removed the component, checked resistance on input/output/enable and soldered a new RT9069-33Gb. Working perfectly on adapter. So may be you too will have success.

[mferna14]

Re: LA-F115P +19VB = 13.6v instead of 19v

Thanks mcplslg123 for this update... I just have to find one RT9069-33GB on a donor, before I start to order them. mon2 & mcplslg123 are great help!!!

[mcplslg123]

Re: LA-F115P +19VB = 13.6v instead of 19v

RT9069-33GB is very sparingly used-I've seen only 3-4 models with this chip so far and that too in Dell only. So may not be available in scrap boards. Better order online and order a couple of pcs more for future usage. The chip is available at less then 1$ per piece

[mcplslg123]

Re: LA-F115P +19VB = 13.6v instead of 19v

For testing purpose, you can use a buck coverter card set to 3.3V on output pin of RT9069 but ultimately the chip needs to be replaced.

[mferna14]

Re: LA-F115P +19VB = 13.6v instead of 19v

"mcplslg123" received this regulator RT9069-33GB today. Replaced it & all worked like charm. No problems at all. Now I got a lot in stock. Thank you very much for all the help.

[mcplslg123]

Re: LA-F115P +19VB = 13.6v instead of 19v

Glad to hear you fixed it.