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#1 |
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![]() Laptop powers on but no display. Caps lock blinks 5 long and 3 short. HP support says that means,
"5.3 (blink) System board The embedded controller times out waiting for the BIOS." I flashed bios with programmer but it made no difference. I cannot find schematic or boardview for this board. I don't have an oscilloscope, but my multimeter has a frequency reading function. I measured the RTC crystal labeled YH2 near keyboard connector and it reads 59.96Hz. None of the large gray coils have any voltage on them. Help? I have attached pics of board. Last edited by grimacelord; 07-15-2021 at 08:16 AM.. Reason: attached pics |
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#2 |
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![]() before the Crystal, are there appropriate voltages in your voltage coils? 3.3 v, 5V, 1.05 V 1.5 v 1.2 V . which label is on the Crystal, 37620 H or 24mhz. you're measuring about 60hz this is the US city network frequency.
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#3 | |
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![]() Quote:
The label on the crystal reads "A952L" The power adapter is HP genuine and is producing 19.5DCV as intended and I can read 19.5DCV at the DCIN jack. attaching pic of crystal and pic of the only large coil I can read any type of voltage on (marked PLB02 at top of pic #2) |
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#4 |
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![]() i think u have right voltage on PR303.
after start measure voltage on pin 8 on bios ic |
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#5 |
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![]() Does the white light come on at the power jack when the charger is plugged in
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#6 | |
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![]() Ok, what the hell? Now, I suddenly have some voltages I didn't have previously. See pic in below post for voltages
Quote:
Yes. Last edited by grimacelord; 07-15-2021 at 12:56 PM.. |
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#7 |
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![]() Here. I marked the locations on this picture where I am receiving voltages. These are are measurements taken at coils except for the one cap which is 19.7v and the pin 8 of the BIOS. Hopefully this helps better explain.
Also, question about measuring the crystal. Do I need to measure it while the laptop is plugged into power AND powered ON? Last edited by grimacelord; 07-15-2021 at 01:00 PM.. |
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#8 |
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![]() You have missing VCore. Check why no voltage is generated on PCH power coil(located near PLZ1-the smaller coil). Without pch power, vcore will not come up. However, i'm assuming that coil near PLZ1 is indeed pch power coil based on experience and i may be wrong. There must be a controller near to that coil which will generate this voltage and you need to check its requirement.
Meanwhile do check resistance(in Ohms mode and not in diode mode) on Vcore & PCH power coil and post here. |
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#9 | |
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![]() Quote:
The three larger coils that we're assuming are VCore have an Ohm reading of 0.5 ohms also. Attaching a pic of PCH/VCORE area if it helps |
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#10 | |
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![]() Quote:
New measurement resistance to ground in ohms mode: The small coil that we think may be PCH power: 14 ohms The three coils we think are Vcore are all 2.6 ohms |
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#11 |
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![]() The power controller nearby to the coils seems to be an OnSemi NCP81215. I'm assuming this should be providing PCH power judging by the datasheet: https://www.onsemi.com/pdf/datasheet/ncp81276-d.pdf
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#12 |
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![]() I took some measurements of the NCP81215 controller. I'll be honest, I'm not 100% sure which of these pins are important, but I checked what seem to be important by their names.
Pin 39 PWM_VID - 0V Pin 38 PGOOD - 1.27V Pin 36 EN (enable?) - 0V Pin 33VCC - 1.05 V Pin 11 PWM/PHTH4 - 1V Pin 10 PWM/PHTH3 - 0 Pin 9 PWM/PHTH2 - 0 Pin 8 PWM/PHTH1 - 0 I am not very familiar with what all of these pins are. I know the schematic gives a description of each one. A few of them I recognize like pins 34/35 SCL/SDA are data lines. Pin 29 is FB or "Feedback", but some of these others I am not sure what exactly they do, even after reading the description The fact that the enable pin seems to not be outputting could that be my issue? I checked for shorts on the data lines and there are none. Not sure what to check here... Last edited by grimacelord; 07-16-2021 at 12:02 PM.. |
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#13 |
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![]() PLA1 is VCCSA not PCH VCore.
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#14 |
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#15 |
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![]() Also, I thought this was interesting as another thread on here had a the same problem and the ultimate issue was the guy was missing VCCSA voltage at coil.
He replaced PQ4012 and it solved his issue. This laptop isn't like his however, so I don't have the same component markings. Last edited by grimacelord; 07-16-2021 at 12:24 PM.. |
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#16 |
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![]() So if PLA1 really is VCCSA coil then I am also missing voltage on that coil just like the guy in the other thread I linked to. It seems to be fed by the component below it labeled PQA1. The markings say: "B09 A03 FMA0193". Having trouble finding it's datasheet.
EDIT: This might be the datasheet: https://datasheet4u.com/datasheet-pd...php?id=1111716 Last edited by grimacelord; 07-16-2021 at 12:32 PM.. |
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#17 |
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![]() Do these readings appear normal? This is on PQA1 and PLA1 which apparently is VCCSA.
PQA1 appears to be a EMB09A03HP MOSFET. (Datasheet= https://datasheet4u.com/datasheet-pd...php?id=1111716 ) Here are the measurements I am seeing in pic attached Last edited by grimacelord; 07-16-2021 at 01:00 PM.. |
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#18 |
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![]() The reading is not correct due to missing gate voltage. This is just a dual channel mosfet. I think there should be an IC driving the gate of this mosfet. Yes PLA1 seems like VCCSA.
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#19 | |
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![]() Quote:
I tested continuity and found that two of it's pins have continuity with gate1 and gate2 of the mosfet, so it seems you were right. This appears to be the IC that drives the mosfet. I checked for voltage on the two pins of this IC that has continuity with the mosfet, but there was 0 voltage. I have no idea what this IC is that is labeled "CGT" and has a board identifier marking of PUA1??? Here is a pic to illustrate: |
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#20 | |
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![]() Quote:
See page 91 in the LA-H501P schematic https://www.badcaps.net/forum/showth...light=LA-H501P |
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