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All sorted, no worries - figured it out myself.
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Any idea if this generation of DELL, using only USB-c for power in requires battery to be installed for the board to powerup?
On USB-c only, the board is power sequencing up to SIO_SLP_S4# OK, but no SUS_ON_EC // On battery only or battery+USB-c it is going all the way to the DDR_DRAMRST# signal OK, before shutting itself down.
Any idea why it is not happy without a battery - I normally expect a board to be more fussy with the battery than without it if experiencing a power fault.
I really dislike the move away from a dedicated simple, robust DC in jack -...
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1.8 v = 450ohm, 1.2v = 480ohm, 5v = 49k, 3v = 13k >> one curiosity with the 3/5v is after the board has had power, these rails stay very low ohms for quite a while until they recover.
I probed around the TPS51285B 3/5v controller and all seemed ok, except when measuring voltage on pin 2, VFB1 - the voltage feedback for the 5v the usb-c would power cycle and renegotiate voltage every time my probe touched the pin. Did not happen on the 3V feedback VFB2 on pin4. I will probably try swapping out this chip, and maybe the PD controller - but for now will leave as is as i made progress....
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Hello Sir.FairRepair -- I think you might be my number one youtube for repair, you know how to put in the hard work! Thankyou.
You are right, a lot of this involves having a known good board and proper documentation. Have neither.
I am currently troubleshooting what to do with a missing PCH_RSMRST# - that seems to be where my power sequence is stopping. The fear is as always, a faulty EC or firmware that can not be recovered, or indeed the PCH is always villain number 1.
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I removed all 5 mosfets from the circuit above, and they all measure high M/OL across S/G/Din all directions and polarity.
Measuring from PL1901, the main inductor in the circuit above with all the 5 mosfets still off the board - across to all other inductors on board, lowest reading is about 47k over to the 1.2v RAM inductor.
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I did find some irregularity with the NVDC mosfet circuit above, but it could just be my knowledge of N-channel and this type of circuit and ISL chip that needs to improve.
So all of the 4 power mosfets, no problems from ground to S/D/G. Probing across the mosfet between S/D/G in both polarities no problems except between GATE and SOURCE on the high side mosfets measure low resistance. But not consistently, I am not sure if something is being triggered by my probing or the circuit itself. Removing the 2 high side mosfets off board, there is no low resistance between S/G on the mosfet...
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The EC is a bga MEC5107. I have no way of knowing where the associated circuit for pin F5 for [B]RTC_CELL_VBAT[/B] is located. I probed around the whole area and could not find batt voltage present - however i do have battery voltage on main power line.
With battery only at battery connector i have 3.3V at [B]3.3V_BAT_LDO[/B], but no CLK_SMB, DAT_SMB, SYS_PRES#. With USBC also present, I have 3.3V on LDO,CLK,DAT - only SYS_PRES# remaining low at 0V. SYS_PRES# seems involved with a battery switch, which the circuit is not on my board and PWR_SHIP_MODE. I concluded I think I am fine...
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DELL XPS 15 9510 LA-K411P (NVDC ISL9538C) NO BOOT / NO CHARGE
Device history > Bit of liquid damage, that I cleaned up and sorted out all bad components.
Current state > No Boot. No charge. It negotiates 20v on all USBC ports, and will even PD charge out – so all of the USBC circuit is probably ok. I have 3.3V + 5V ALWP present and stable. PCH has its 3V,1.8V,1V. On the board, PCH,EC,ISL,PD chips are all powered on and active. Power button has 3V, board is being signalled by it but not responding. I have 20V USBC in OK, I have a 12.6V main power rail ok. The battery was undervolt dead, so had to manually charge each cell individually...
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This P1 board does indeed have 1st.P + 2nd.N channel DCin mosfet pair, neither of which are driven by the BQ24780.
Not a completely new theory invented by me, again i will upload the schemtatic pages of interest highlighted in green.
You can clearly see that the BQ24780 chip, ACDRV pin is floating - going nowhere as indicated by the big X - not driving any mosfet.
You will also see, the 2 DCin mosfets, first being a P channel, 2nd being an N channel. The N channel gate is being driven from the TE1 chip (thinkengine power sequencing EC) on the DCIN_DRV line.
[ATTACH=JSON]{"data-align":"none","data-size":"full","data-attachmentid":3209030}[/ATTACH]...
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BQ24780
I used green marker to highlight areas of interest. It definitely is not the BQ driving DCin mosfets from what I can understand, but the TE1 chip - which is a lenovo thinkengine chip right next to the main EC chip. This TE1 looks like a seperate EC lenovo thinkengine power management chip.
I have already replaced the TE1 chip, with no change. The chip was an aliexpress order, unsure if a good chip or not or whether this chip has to be programmed / can be programmed from the main EC however I am getting the exact same response from the board so will assume both...
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LENOVO P1 G1 (X1 EXTREME) 0.8V MAIN POWER RAIL [LPM-1]
No shorts on any main power rails.
All power mosfets over the whole board test good.
Have 20v into first DC in mosfet, when power button is pressed main power rail is at 0.8V. Not sure if it is the EC or BQ creating that 0.8V or?
The 2 input DC mosfets are not driving voltage, 2nd mosfet is N channel and no 25V on the gate. Again is this coming from the EC or BQ chip.
BQ chip has 25.6V at ACDRV.
Thankyou
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Was asked twice for serial number, rules - fine.
Hoaca gave me a random file, told me to "try it", with absolutely no further context or information of what that file I was told to try was.
Is there a rule to provide useful information for any file told to try, otherwise how do we know what we are being given, whether it is malicious, what was done to the file, how will anybody learn anything.
Thankyou...
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That CH341 voltage "mod" creates more problems, I would leave it as is.
However, if you have 40 units to program, do yourself a favour and get a T48 programmer - you will be in pain running at the speed of the CH341.
Unfortunately, you will be best to remove the bios chip from the mainboard - normally creates more problems leaving it on the board, especially as you say every read is different.
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