Hi guys, I got an HP 15 mobo # EPK50 LA-G07EP rev 2.0 not starting up on battery? Recently the battery completely died, wouldn't hold a charge, so I used it for like 3 or 4 days until I ordered a new battery. I ordered a new "OEM" battery and replaced it. It wouldn't start with new battery, figured it was dead and plugged it up and powered it on to see that new battery was like 60% charged. So it seems It won't start on battery if it is not plugged in. It charges fine and lets me use it while not plugged in. If I use it and shut it down and try to power it back on it'll start from power button without being plugged in. But if I leave it overnight and try it won't power on from battery. I am not getting the standby voltages on PL302 or PJ302 with battery connected or AC connected. I am not able to test if this is an issue with new battery as the old one is dead and won't charge.
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Check the ENABLE voltage for this LDO regulator leg. Confirm if the LDO rails are active or not.
The ENABLE voltage is built by the 2 resistors that feed off the main power adapter rail as copied below.
Assuming the enable signal voltage is OK, then proceed to test if this rail is being shorted. Remove all power. Meter in resistance mode. Measure the resistance to ground of PL302.
Also interested in checking if the dual diode @ PDB1 is working properly. Remove all power. Meter in DIODE mode.
Red meter probe onto pin # 2; black meter probe to pin # 1 = Vcc on the charger IC (pin 20). The meter should conduct. Confirm this. Then reverse the meter leads and the diode should block with 'OL'.
Repeat the same test using pins # 3 and pin # 1 on this diode. If you find the diode conducts in both directions, then this dual diode is defective (a common fault) and must be replaced.
To charge the battery, the power adapter must be suitable and ACOK should be OK with a logic '1' voltage.Comment
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No rail can be shorted to GND as the mb works fine with display.
I'll prefer to check the resistor value on SDA/SCL/SRN/SRP/ACN/ACP pins and check the connectivity to respective CLR.Comment
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Resistance to ground of PL302 on both sides is 33K -37K ohms depending which color probe I have on ground. But I see that PLB11 has 12V when connected to battery and AC but discharges to to 0 when no charger is removed. Also the I have not been able to locate PDB1 and PR307,309 I think we have different schematics or boards. Also I have no standby voltages on any of the caps or coil when a battery is connected and no charger connected. The issue is somewhere near PL301 as I have no voltage around those caps and the coil itself. So CL2 is open and I get no voltage on it isn't that the current sense resistor or coil? Interestingly CL2 is also directly on the backside of the power switch on the board.Last edited by SuperAman; 12-17-2024, 11:28 PM.Comment
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So CL2, which is to the right of the screen connector is open. Aside from that the cap below PRB11 writing is short when I test it for continuity but when I test it in diode mode (red probe on ground) I get a reading of 547 on each side. I believe that is ground pad all those caps and resistors are dumping to. I checked most of the components and I didn't see anything that else that stood out to me.Last edited by SuperAman; 12-18-2024, 10:09 AM.Comment
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mcplslg123 mon2 So it suddenly started working. I cleaned the board last night but the hinges was falling apart so I decided to test for voltages and I wasn't getting any then suddenly I got 11.2v on the battery lines and it and it turned on with battery power only. I completely removed screen assembly and it powers on with battery only. I will try to use epoxy to fix the hinges and will test once it is all together. I wonder if the hinge was causing a short or issue with power button but it is weird it only wouldn't power on when the AC adapter wasn't connected.Last edited by SuperAman; 12-18-2024, 12:59 PM.Comment
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Remove all power. Meter in resistance mode. Review if PQB13 is leaky. PQB13 is the battery mosfet that powers the logic board when using only the battery.
Test this mosfet using the resistance mode of your meter:
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. Each should be hundreds of k ohms or higher otherwise this mosfet may be leaky and needs to be replaced.
Suggest to also investigate the DCin mosfet PQB12 (ie. 2nd DC in mosfet) which is often defective on such cases.Comment
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thank you mon2 it help me a lot ^_~Originally posted by mon2 View PostCheck the ENABLE voltage for this LDO regulator leg. Confirm if the LDO rails are active or not.
The ENABLE voltage is built by the 2 resistors that feed off the main power adapter rail as copied below.
Assuming the enable signal voltage is OK, then proceed to test if this rail is being shorted. Remove all power. Meter in resistance mode. Measure the resistance to ground of PL302.
Also interested in checking if the dual diode @ PDB1 is working properly. Remove all power. Meter in DIODE mode.
Red meter probe onto pin # 2; black meter probe to pin # 1 = Vcc on the charger IC (pin 20). The meter should conduct. Confirm this. Then reverse the meter leads and the diode should block with 'OL'.
Repeat the same test using pins # 3 and pin # 1 on this diode. If you find the diode conducts in both directions, then this dual diode is defective (a common fault) and must be replaced.
To charge the battery, the power adapter must be suitable and ACOK should be OK with a logic '1' voltage.
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