Re: ACER 5742 Dead M/Board
Just another photo.
Just another photo.
Attached Files
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Re: ACER 5742 Dead M/Board
Photos of voltages.Attached FilesComment
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Re: ACER 5742 Dead M/Board
Your gate voltage at PQ51/52 is still wrong at 18v. it should be around 6-8V. Unless that is fixed PQ52 wont pass 19V to P3(Thats your B+ line). So effectively you are having 6V instead of 19V at B+ line. So laptop will not turn on.Comment
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Re: ACER 5742 Dead M/Board
Mcpisig Techtiger has been helping me with this laptop and has already explained this to me, can you suggest what may be causing the problem???Comment
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Re: ACER 5742 Dead M/Board
PQ56/58-Either one of them or both may be faulty in my opinion.Comment
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Re: ACER 5742 Dead M/Board
Hi mcpisig123, thanks for replying, I will wait till techtiger gets back to me as he has been my main man, many thanks.Comment
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Re: ACER 5742 Dead M/Board
Yes, its always wiser to get more opinions and@techtiger has been helping a lot of people in the forum. keep up the good job@techtiger.Comment
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Re: ACER 5742 Dead M/Board
techtiger mcpisig123, thank you for helping. I haven't had time to remove pq56/58 I tested them in circuit and seem ok. When I removed pq52 I tested pads and they are shorted to gnd. I think B+is shorted. See photo these caps all show the lowest ohm reading 28ohms dont know which one or more. the 2 large caps are marked C1 and C2 but I cannot find them on the schemeatic. I found 4 more same value tested them in diode mode red to gnd black to cap these measure very low compared to the same value caps 252 to 31. The large caps are 10uF 25v (1206) Silly question which are likely to fail first???
I cannot find what line all these caps in photo are on.Attached FilesLast edited by John McGivern; 12-12-2019, 06:14 AM.Comment
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Re: ACER 5742 Dead M/Board
C1/C2 caps are connected to +VGA_CORE(page25). The 7 small caps placed together-3 on the right side seems in bad shape as per your pics. can you remove them and test out of circuit. Btw, this is part of cpu vrm circuit-so low resistance is expected.Comment
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Re: ACER 5742 Dead M/Board
All 3caps are ok. Do I need them.Comment
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Re: ACER 5742 Dead M/Board
Removed pc248 same voltage on pq drain 6.24v replaced pc248, removed pc249 voltage on drain same. Only pq56 and 58 to replace but I think these are good.Comment
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Re: ACER 5742 Dead M/Board
Disaster pc248 ping lost 0402 package.
Does anyone know where to buy cut reel smd caps or acer 5742 cap selection pack??? UK
I could have bought a used m/b cheaper than what I have spent on this M/B but I am determined to repair this plus it's a good learning process. The really frustrating part is acquiring parts and waiting for them to arrive, many thanks, John.Comment
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Re: ACER 5742 Dead M/Board
MB should work even without PC248Comment
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Re: ACER 5742 Dead M/Board
Unfortunately no how crucial is cap value I have board from hard drive with similar footprint but difficult to measure cap value mcpisig123 I changed pq56 Will change pq58 they are difficult to desolder due to other components being so close this board has large copper traces and requires a lot of heat even removing small packages and my skills are lacking a bit when trying to remove 0603 and 0402, thanks for advice, John.Comment
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Re: ACER 5742 Dead M/Board
Hi, changed pq56 applied 3.3 and adapter. One side od pr371 is 3.3v other side is 0.290v this is pq59/63 gates. 19v pq51 and drain of pq52 source is still 6.24v and pq52 still removed from board.
Merry Xmas and a Happy New Year to all Bad Cap Members.Comment
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Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
[HELP] Acer AN515-55 (LA-J871P Rev: 1B) – Board won't power on after GPU investigation – Suspecting Super I/O or PCH
Hi everyone,
I'm working on an Acer Nitro 5 unit with the following specs:- Motherboard: LA-J871P Rev: 1B
- Model: Acer AN515-55-59MT
- S/N: NHQ7JAL00403906A973400
- SNID: 03902728734
Initial Issue
The laptop initially presented graphic issues and driver failure (Code 43) for the GPU.
After preventive maintenance (cleaning, thermal paste, etc.), it powered on normally. We disassembled it again to inspect the GPU, reassembled... -
Hi everyone,
I have a NM-A321 board that is dead, with no power at all.
When I received the laptop, the +5VPMIC line was shorted. Removing the PU3 (ISL95905) solved the short, so I ordered and replaced the ISL.
With the new ISL, the short is gone, but still no voltages at all. I measured the following rails:- +3VALW
- +5VAUX
- 1.2VSUS_PWRGD
- 3VALW_PGD
- 1.05VAUX_PWRGD
Additionally, the ISL95906 (PU3) is not getting any voltage on the VIN rail.
The only place on the board where I find any voltage is on the first MOSFETs, specifically:... -
I'd like to offer an Acer IPIMB-AR Rev: 1.02A fullflash BIOS (cleaned ME region). The model is for Acer Predator G5920.
It is a model that is based on Intel Z77 PCH and doesn't have on-board graphics and video connectors.
I suppose it doesn't have any restriction about discrete graphics cards (I mean they don't have to be in a whitelist).
Please don't mistake this mainboard with a similar model with on-board graphics and based on Intel B75 PCH.
Jumper FLASH_OVERRIDE
default position: 1-2 - BIOS area protected
position 2-3 allows to dump BIOS or write...06-26-2025, 05:15 AM -
All left and right refers to looking from rear of TV (or looking from front with TV upside down)- TV came with vertical bars and no image. Found faulty TVS on left buffer board. Also replaced T-Con (may have damaged the original while hot air removing components, board has slight warp) and have full image but few horizontal lines on the screen. Some of the lines appears to be 2 pixel tall while others are 1 pixel tall.
- Disconnecting left and right buffer board potentially reveals problems on both sides with different signals (unless this T-Con require jumper like Samsung FB_TRDY1&3) Fault
Comment