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Last edited by Techtiger; 11-19-2019, 02:10 AM. -
Re: ACER 5742 Dead M/Board
source 18.9ohms, gate 14.5kohms, drain 3Mohms dropping unstable.
See attachment photo. Thank you.Attached FilesComment
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Re: ACER 5742 Dead M/Board
latest update could do with some help.
Replaced chip, cpu,fan so injected 19v see attachments for voltages.Attached FilesComment
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Re: ACER 5742 Dead M/Board
If you look back post 32# pic you will understand how the 1st 2 fets workingComment
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Re: ACER 5742 Dead M/Board
Techtiger, yes it's 4v.Comment
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Re: ACER 5742 Dead M/Board
Was the Battery inserted when you check the voltage if so remove and test again or the PQ52 is faulty what voltage you get PR297 pin 1? PU18A is a comparator it’s not working properly pin3 should be 3.6VLast edited by Techtiger; 11-23-2019, 11:27 AM.Comment
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Re: ACER 5742 Dead M/Board
Techtiger, no battery inserted, pin 1 = 0v. I will try changing lm393. Then pq52.Comment
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Re: ACER 5742 Dead M/Board
Fitted lm393 and pq52 D=5.3, G and S=18.68. PQ 51 D=19, G andS=18.68
LM 393 Pin1=13,14,1.3v fluctuating drawing 55mA
Pin2=10.8
Pin3=13.4
Pin4=14.0
Pin5=13.5
Pin6=13.4
Pin7=14.0
Pin8=18.5Comment
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Re: ACER 5742 Dead M/Board
I doubt your measurements. How can gate voltage of PQ51 and 52 be different when they are tied together??Comment
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Re: ACER 5742 Dead M/Board
I have double and treble checked voltages pq51 and pq52 are the same as post 50.
Lm393 pin1 is all over the place from 14v down to just under a volt sometimes steady at 1.3v I really have no idea what is wrong. I don,t think pq52 was faulty but replaced it anyway so I'am stuck at present. I have a scope if that is worth using but only 20Mhz analogue. Many thanks.Comment
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Re: ACER 5742 Dead M/Board
There is no voltage on Zener diode1 near pin 1 lm393.Comment
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Re: ACER 5742 Dead M/Board
Techtiger, You where right mate found 19v one side of pr296 other side 0.0v where can I buy 10kohm 0402 5% are they thick or thin footprint nothing is easy with these smd components. May still have more faults very long learning process for me ha ha!Comment
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Re: ACER 5742 Dead M/Board
Hi, pretty sure Pr296 open should arrive tomorrow.Comment
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Re: ACER 5742 Dead M/Board
Arrived today excellent service. Ordered 50 of each value after pinging 4 and losing them while attempting to solder I finally managed to solder one.
Tested with dmm pin 1 is now shorted to gnd and both sides of the new resistor shorted to gnd and PD1 no voltage either way when tested diode mode back to the drawing board. This was the first 0402 component I have attempted I am ok with 0805 but these are really small. When I removed the old resistor I tested the pads they where shorted will try to find what is causing the short.Comment
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Re: ACER 5742 Dead M/Board
Update.Attached FilesComment
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Re: ACER 5742 Dead M/Board
More Pictures.Attached FilesLast edited by John McGivern; 12-03-2019, 03:01 PM.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