Good morning.
This MacBook came to me with the defect that it doesn't turn on, even the green or orange LED doesn't turn on from its power supply with magsafe connection. While disassembling the motherboard I noticed the following problems:
UG400 with a hole, I desoldered it.
I find very low resistance to ground on the LG801 coil. I unsolder UG800 and the short disappears. With these two components desoldered, I connect the magsafe and the light turns on orange but still doesn't start. I order a new Ug400 and UG800 but nothing changes, same problem. I check the components under...
robgerr
Senior Member
Last Activity: Yesterday, 05:41 AM
Joined: 04-05-2012
Location: Ragusa
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Macbook A2485 ( Main 820-02100-A) no power
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The modified bios solution to deactivate the soldered ram works but the problem is that windows downloads the updated bios version through updates and once the bios is updated the soldered ram deactivation fails. I solved it this way instead. I downloaded the latest bios from the Lenovo site, I cut the parts relating to the flash software, I modified the bios to deactivate the soldered RAM. Now the machine works, if I enter the bios the serial entry is invalid. In this way Windows will no longer be able to automatically update the bios because it does not recognize the serial number and therefore... -
Macbook A1708 Main 820-00840A
Good morning, this macbook does not power on. By connecting the (non-original) power supply it negotiates 20V and absorbs 1.40A (battery connected and perhaps charging). Disconnecting the battery it stores at 5V and after about 5 seconds it rises to 20V and absorbs 20 mAmp. I did a quick check under the microscope but I didn't find any oxidation damage, it seems perfect. I checked the main rails and they seem ok.
PPBUS_G3H 13,070v
PP3V3_G3H 3,42v
PP5V_S5 5v
PP3V3_S5 3,31v
PP1V_S5G 1v
PP1V8_S5 1,80V... -
Hi mon, SL4503 not present, only pad. I fix problem, cutted line lcd_bl_pwm and made jumper. Attached photo. Now backlight work at max (no backlight control).
in any case the customer is fine with this without control
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20240724-162428-8820.jpg","data-attachmentid":3315518}[/ATTACH]...Leave a comment:
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I think the problem is lcd_bl_pwm because voltage is 0v (pin 34) but i'am not sureLeave a comment:
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Hi mon2, thank's for your reply. Pin 32 is connected to gnd, enabler is on pin33.Leave a comment:
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Asus N580VN no backlight lcd. Main X580VN rev 3.0
Good morning forum. , This notebook has problems with the backlight being absent. If I shine a flashlight on the screen, i can see the image. I tried to change several LCDs but the same problem. When I disassembled it, I noticed the LVDS connector was a little burned in the backlight pins. I also found oxide in the LVDS connector on the motherboard. I replaced the LVDS cable, same defect. I replaced the LVDS connector on the motherboard, same problem. I took some measurements on the pins (I used the boardview of the X580VD).
pin 36,37,38,39 19,40v
pin 35 no connected
pin... -
This is the schematic I found, but unfortunately it doesn't match serigrafy.
[url]https://www.badcaps.net/filedata/fetch?id=2052989[/url]https://This is the schematic I foun...52989[/url]Leave a comment:
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Hi Mon2 and thanks for replying. I downloaded the schematic but I don't remember where. I'll send you a photo of the oxidized component IC charger replaced (picked from other same main board)
[ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3161154}[/ATTACH]...Last edited by SMDFlea; 12-11-2023, 04:58 PM.Leave a comment:
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Toshiba L50-B-1Q0 (Main DABLIDMB8E0 REV:E) no power on
Good morning forum. This laptop comes into my laboratory with the defect that it won't turn on. By connecting the bench power supply I have an absorption of 1.56A (battery charging), I disconnect the battery, I have an absorption of 0.01A. I give the power on but it doesn't react. I check the mainboard and I notice the Isl88732 charger with oxide and a little burnt between pins 7-8. I remove the charger, clean the pads and solder another ISL coming from another identical board. I also find a bit of oxide in the power button connector. I clean the connector, clean the flat that goes to the power... -
Re: Asus K3500P Main (X7400PC R2.2) Bios Dump Reques
Thank's SMDFlea, serial number writed in bottom cover: MAN0CX229059426Leave a comment:
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Asus K3500P Main (X7400PC R2.2) Bios Dump Reques
Good morning forum, I'm trying different bios to try to resurrect this machine, with all the bios tried the machine turns on, the fans turn but the screen is black. I tried to download the correct bios from the Asus website (x3500PC by reading the QRCODE from the motherboard) but this is a PFAT AMI, I managed to decrypt it but I get several files and rebuilding it is very laborious, I tried with the uefi tool to extract only the main bios and cut the decrypted one and rebuild it in hex but it doesn't work the same. Wondering if anyone has a dump for this main board. I thank you.
Attach... -
Asus K3500P Main (X7400PC R2.2) Bios Dump Reques
Good morning forum, I'm trying different bios to try to resurrect this machine, with all the bios tried the machine turns on, the fans turn but the screen is black. I tried to download the correct bios from the Asus website (x3500PC by reading the QRCODE from the motherboard) but this is a PFAT AMI, I managed to decrypt it but I get several files and rebuilding it is very laborious, I tried with the uefi tool to extract only the main bios and cut the decrypted one and rebuild it in hex but it doesn't work the same. Wondering if anyone...Leave a comment:
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Re: hp dv3 dis to uma?
In my case laptop the conversion in Uma worked by removing R166 and inductor L6. My mainboard is 6050A2371701-MB-A01with i3 350M CPULast edited by robgerr; 11-03-2020, 12:32 PM.Leave a comment:
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Re: projector Cheerlux CL720 with damaged psu
I thank you for the answer, but do I have to connect the 12v in the primary side of the transformer or in the secondary?
I noticed that in the primary and secondary side of the transformer there are more outputs, in any case this power supply works with two voltages, 12v and 35v in outputLeave a comment:
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Re: projector Cheerlux CL720 with damaged psu
[attach]194993[/attach]
[attach]194994[/attach]Re: projector Cheerlux CL720 with damaged psu
[attach]194993[/attach]
[attach]194994[/attach]...Leave a comment:
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projector Cheerlux CL720 with damaged psu
Hello to all friends of the forum. This projector will not turn on after a power surge. Disassembling it, I found the psu with burnt components, I found a large carbonized resistor, burnt smd resistors, short power mosfet, and two small smd smeared transistors, The ic switch is a ld7575ps. Do you think it is possible to go back from another scheme to the components that can be replaced since the names are not legible?... -
Re: Acer E5-571G Black Screen (a5wah la-b991p)
Good afternoon friends of the forum. I replaced PU801 but the defect remains. on pin 1 of pu801 I find 1.05V. Other suggestion?Leave a comment:
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Re: Acer E5-571G Black Screen (a5wah la-b991p)
pin 121 3,3vLeave a comment:
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Re: Acer E5-571G Black Screen (a5wah la-b991p)
is correct value?Leave a comment:
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