ianbak
Member
Last Activity: Yesterday, 07:44 AM
Joined: 04-14-2023
Location: Hampshire
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Definitely the second, and probably the first as well! -
Toshiba R940 with water damage
Hi,
I have a Toshiba R940 which doesn't power on (fully) due to liquid damage. The mother boards is FAM2SY2 A2356A.
Most of the corrosion has cleaned up well, although I can see a few joints that need touching up. More troubling is the fact that one of the components appears to have been eaten off the board. You can see it if you zoom into the attached photograph, and it is clearly missing in the close up view.
I can't find a schematic for this motherboard, and wondered if anyone had any ideas about identifying the missing component?... -
Hi, I have a Lenovo L470 that does everything apart from POST - it powers on, bleeps if there's no RAM installed, all voltages are present, the CPU warms up and the battery charges. My working assumption is therefore a corrupted BIOS.
It would therefore be great if someone could take the configuration information from the attached BIOS dump and copy it into a fresh image for me.
The laptop is an L470 Type 20J5 with a NM-B021 motherboard, serial number PF-0UY199
Thanks!...Leave a comment:
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Do you have a thermal camera? You can usually spot a dead PCH because any heat tends to occur in a small spot, rather than uniformlyLeave a comment:
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And it's now installed and working perfectly! Thankyou so much - it's way better to have the tools that allow you to do these things for yourself!...Leave a comment:
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OK, that's generated a patched file for me - I'll let you know how I get on when it's back in the laptop. Thanks!...Leave a comment:
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My apologies, I didn't realise that both were necessary....Leave a comment:
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Hi, Would someone be so kind as to remove the Admin password from my Latitude 5300 BIOS? I have attached the dump of the 8 MB Winbond 25Q64.
The Service Tag of the laptop is 8LWNMW2 (although the BIOS dump could contain something different, as it is a replacement board) and the board is a 18827-1...Leave a comment:
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With something as new as a 450 G6 I'd start by using the USB method to recover the BIOS instead of trying to program it myself!Leave a comment:
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If that's the correct schematic then the +ve wire should go to R2502 - work out which end of it is connected to D2501 pin 3 and then connect to the other one. The -ve can go to any ground point.Leave a comment:
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Another successful recovery with SMDFlea's BIOS file and the Function + R trick! Thanks guys!Leave a comment:
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That was the problem - a broken trace between ACN and the current sense resistor. I located the break, bridged it, and now have a working laptop.
Thanks for your help - I think I'd have given up before finding the fault without it!Leave a comment:
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We might finally be onto something here! ACN to ACP is open circuit, which explains how there can be a 0.7V drop between them when they should be bridged by the current sense resistor! The current sense resistor itself has continuity (measured across terminals 1 and 4) and both ACN and ACP are MOhms to ground.
I'll continue to investigate this tomorrow....Leave a comment:
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I've just re-measured it, with and without the battery present, and the numbers are all still as before.Leave a comment:
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Sorry for the delay in replying - busy day yesterday.
There was no battery attached when those measurements were made. With the battery attached and power connected I get the following:
Pin 1 - ACN - 10.6 V
Pin 2 - ACP - 11.3 V
Pin 3 - CMSRC - 24 mv
Pin 4 - ACDRV - 18.3 mV
Pin 5 - ACOK - 3.3 V
Pin 6 - ACDET - 2.9 V
Pin 7 - IOUT - 0.8 V
Pin 8 - SDA - 0.1 V
Pin 9 - SCL - 3.2 V
Pin 10 - ILIM - 0.6 V
Pin 11 - BATDRV - 17.6 V
Pin 12 - SRN - 11.3 V
Pin 13 - SRP - 11.3 V
Pin 14 - GND - 0 V
Pin 15 -...Leave a comment:
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Yes, directly on the charger IC pads.
I tried reflowing the 24735, and it's all still as before with ~27 mV on ACDRV. I tried swapping the capacitor too - the one on the donor board measured 1.2 uF before I put it in, which is consistent with the 1.0 uF specified in the schematic.Leave a comment:
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With PRB9 removed (it took me a while to identify it!) ACDRV is still at 26 mV, he same as beforeLeave a comment:
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The MOSFETs were replaced like for like from a donor board.
PQB11 Source/Drain - 3.2 MOhm, Source/Gate - 3.7 MOhm, Gate/Drain - 6.3 MOhm
PQB12 Source/Drain - 4.3 MOhm, Source/Gate - 3.7 MOhm, Gate/Drain - 6.0 MOhm...Leave a comment:
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Here is a full set of voltages for the BQ chip:
Pin 1 - ACN - 347 mV
Pin 2 - ACP - 913 mV
Pin 3 - CMSRC - 34 mv
Pin 4 - ACDRV - 24.3 mV
Pin 5 - ACOK - 0 V
Pin 6 - ACDET - 2.93 V
Pin 7 - IOUT - 0.7 V
Pin 8 - SDA - 2.1 mV
Pin 9 - SCL - 1.9 mV
Pin 10 - ILIM - 0 V
Pin 11 - BATDRV - 2.07 V
Pin 12 - SRN - 1.07 V
Pin 13 - SRP - 1.07 V
Pin 14 - GND - 0 V
Pin 15 - LODRV - 0 V
Pin 16 - REGN - 5.98 V
Pin 17 - BTST - 3.86 V
Pin 18 - HIDRV - 1.08 V
Pin 19 - PHASE - 1.07 V
Pin 20 -...Leave a comment:
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I have attached a schematic for the board. The replacement charger IC is a genuine BQ24735, as originally used by HP. There is a reverse voltage protection circuit shown on the circuit diagram, but on my board the components are not present.
[COLOR=#8e44ad][B][SIZE=20px]LINK to schematic[/SIZE][/B][/COLOR] -> [URL]https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/schematic-requests-only/108253-hp-15gw-la-h32ap-boardview-please[/URL]I have attached a schematic for the board. The replacement chargerLeave a comment:
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