mon2
Badcaps Legend
Last Activity: Today, 12:05 PM
Joined: 12-15-2019
Location: Windsor, Ontario
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Test the voltage on the SMBUS / I2C lines on the BQ24780S. The BMS uses these lines to offer the battery details and the 100% charge status is often linked to issues with these lines. -
These are diode mode measurements.
Looks low. Switch to the lowest resistance mode. Measure the resistance to ground of the same location. What is the resistance in ohms?...Leave a comment:
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Brother, I think we are almost in parallel on the A1706 case.
Your USB rails are also looking low.
What is the voltage that you measure for these inductors to ground?
Concerned about the following:
A diode mode measurement of 0.080V on L8000 (P1VS4_PHASE) is not normal and typically indicates a short circuit or a severely degraded component on that rail.
Measurement Analysis- Expected Reading: For a 1.4V phase rail like P1VS4_PHASE on a MacBook Pro (such as the A1707), a healthy diode mode reading is typically between
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The lines are not shorted / shunted so not the fault.
My bad - your board is at the proper PPBUS_G3H voltage of 12v6 for a normal boot. Too many numbers in my head.
Suspecting that you have a shorted part on the board that is causing this power cycling. Test the resistance to ground of each and every inductor (grey coils). Report any low resistance to ground for a review.Leave a comment:
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Working on a similar pig in the shop now (A1706) and not having fun. At least 2 of the CD3215 are defective, possibly more due to fake(?) power adapters being used. Client wants it working to retrieve their data.
Test the voltage to ground of:
SMBUS_SMC_5_G3H_SCL
SMBUS_SMC_5_G3H_SDA
Should be ~3v42. If it is not, test the resistance to ground for each of these signals. These signals are open-drain signals that must not be shunted to allow for the PPBUS_G3H to be escalated to ~13v for the normal boot process.Leave a comment:
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If these are resistance values to ground then the main power rail is shorted. Test the resistance to ground of each and every inductor on the board. Confirm if you see a similar measurement near the CPU....Leave a comment:
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I would, yes. At least remove each off the board -> allow them to cool down -> measure the same points on the mosfet on your work bench to confirm. Appears that both of these mosfets are defective.Leave a comment:
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Yes, very possible that the CPU is shorted due to the voltage injection of the main power rail causing the CPU to heat up. This implies that the high side mosfet for the CPU power supply is defective and is leaking.
Confirm this by removing all power and measuring the resistance from the main power rail and the CPU core voltage rail. If this resistance is low, the high side mosfet is defective and the CPU has been killed from this high voltage rail.Leave a comment:
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Can you double check this measurement? This is way too high and should be 1v8 or lower. Otherwise, something is wrong here.
That is, the enable signal is driven by a logic gate that has 1v8 for the VCC pin so the max voltage here should be 1v8.
Perhaps you have measured one of the VIN pins on UC300?
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Excellent.Leave a comment:
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The HIDRV and LODRV mosfets used for the battery charging are suspects. The mosfets are N-channel for both locations with the BQ charger ICs.
Remove all power. Meter in resistance mode. Measure each, the high side and low side mosfets to test if they are defective. The charging voltage is very low to charge the battery.
Measure:
source / drain
source / gate
gate / drain
for each. Each should be hundreds of k ohms else could be defective.
Also, measure the resistance between SRN / SRP directly at the charger IC to inspect...Leave a comment:
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What is the resistance to ground (no power to the board) of PP5V_S2?
Do you have a voltage on the enable pin for this power rail @ P5VS2_PWR_EN?
The above are linked to UC300.
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Nice hint...
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Boardview shows one side is to ground. Linked to the local LAN controller / connector. My thoughts are this is a common line (CL) emi filter.
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If you hear a chime, the board is booting. Try the caps key. Does the caps key led toggle? If yes, the operating system has booted and you are at the login screen. Ignore my earlier post and update this thread.Leave a comment:
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A blinking code of 2 Amber and 1 White on a Dell computer generally indicates a CPU failure or a system board initialization error, often meaning the processor is not detected or is malfunctioning. This usually requires a hard reset, BIOS recovery, or hardware servicing to resolve.
Troubleshooting Steps:- Hard Reset: Unplug the charger/AC adapter and, if possible, remove the battery. Hold the power button down for 30–60 seconds to drain residual power. Reconnect the charger and attempt to power on.
- BIOS Recovery: Try a forced BIOS update/recovery by holding Ctrl + Esckeys while
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Test the nand flash power rail for voltage and also resistance (without power).
PPVCCQ_ANI_SSD0 (1.8V): This is for the NAND. Shorting here is a common failure.
Attempt a DFU.Leave a comment:
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measure the resistance to ground of +5vs.
The emb20n03v mosfet is also a suspect.
Measure:
source / drain
source / gate
gate / drain
Of this mosfet with no power to the board....Leave a comment:
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