Greetings,
kindly I need some help.
On a working motherboard of an A1466 emc 2632 MD760LL/B, I replaced the efi eeprom with one purchased on ebay. When I did this operation I didn't have an adapter to read the contents of the memory, so I got one already programmed.
Unfortunately now the MacBook doesn't turn on anymore and when I connect the Magsafe the charging LED doesn't turn on.
Has this ever happened to anyone? Could it be due to the contents of the chip or how I soldered it?
Thank you
sempre
Member
Last Activity: 08-05-2024, 01:56 PM
Joined: 11-11-2020
Location: roma
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Macbook Air A1466
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Re: HP DMI Tool NBDmiFit
Hi, I replaced the motherboard of a hp 820 g2 with one purchased on ebay,
I would like to know if I can change the serial number, so as to insert the one on the motherboard that was there before. I no longer have the old motherboard and I don't have the copy of the previous bios.
Thank you, -
Re: Samsung T22b300 power supply problem
rm802 was the right solution! Thank you all!Leave a comment:
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Re: Samsung T22b300 power supply problem
I checked rm802 (close to the transformer output) and it is open! Tomorrow I try to replace it, I have to look for it on some other board.
Thanks everyone for helping me!...Leave a comment:
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Re: Samsung T22b300 power supply problem
I replaced icm901s, the 220pF 1kV capacitor and a fuse, all shorted or blown.
Next I checked and replaced rm803 and two capacitors one on 5V another on 58V.
The TV is powered at 220vacLeave a comment:
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Re: Samsung T22b300 power supply problem
Thank you for your reply.
In this board there are mainly 5v and 13v for the main board, and 58v for the leds. When there is nothing connected I find the voltages at the right value. When I connect a load, they oscillate and (the 5v goes down to 0 then back to 5).
I redid the reading on the 100uF 450V capacitor and there are between 295v and 297v. I noticed that these values drop by a couple of volts when I connect the main board and the leds, the reading fluctuates a little....Leave a comment:
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Re: Samsung T22b300 power supply problem
300vLeave a comment:
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Re: Samsung T22b300 power supply problem
Hello,
Thanks for the reply.
I first replaced rm803, (I used a 0.39ohm) because it seemed slightly cracked, the measured value was still correct.
When I removed the resistor, I could check the diode dm803 (with the curve tracer) and it's ok.
I have powered the board and connected only the leds and there is always the same problem.
Then I replaced the 47uF capacitor next to the strw ic and the 1200uF and 100uF 100V capacitors.
Nothing has changed.
I tried to attach an animated gif but I couldn't (now...Leave a comment:
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Re: Samsung T22b300 power supply problem
Yes, thanks for the reply, I checked that too.Leave a comment:
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Samsung T22b300 power supply problem
Hi I'm trying to repair the Samsung lt22b300 power supply. I replaced the srtw6052 chip that was shorted together with the blown fuse and a blown 222 1kv capacitor.
Now if I check the output voltages they all seem ok, but as soon as I connect a load, led or mainboard, all the outputs become oscillating (backlight flashes).
To rule out problems with the LEDs or the main board, I tried to replace the power supply board (PD23A0Q) with a borrowed one from another working TV and everything works regularly.
I checked all the diodes and non-smd capacitors... -
Re: macbook A1398 EMC 2674 no chime and black screen
Actually I removed it with hot air I soldered it with a soldering iron, only I did it at least 4 times to test the flash. In the end, I didn't clean the card well. I'm pretty sure the problem is in the flash content. Is there anyone who please, before I change it (I ordered one and I'm waiting for it) who can suggest me what else to check? It seems strange to me that with the oscilloscope I cannot see the clock on pin6. Thank youLeave a comment:
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Re: macbook A1398 EMC 2674 no chime and black screen
Hi, a little update, I found the schematic of this motherboard and checked the connection to the flash and I'm ok. Miso and Mosi are set at 3.3v,I also checked with the oscilloscope that Miso and Mosi are set at 3.3v, there is no activity.Leave a comment:
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Re: macbook A1398 EMC 2674 no chime and black screen
Here attached are two photos a little better. Pin 3 goes to 3.3k pull up resistor, and the two? I also checked gnd and 3,3v and they are ok, for the other pins unfortunately I don't have the schematic, do you know where they are connected?
Thank you so much....Leave a comment:
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Re: macbook A1398 EMC 2674 no chime and black screen
Here is a photo attached...Leave a comment:
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Re: Need help for bios a1398 emc 2674 N25Q064A
Thanks !!
I checked the file you sent me and I saw that for the mac model MGXA2X (EMC 2876 mid 2014)
MacBook Pro 15-Inch 2.2 GHz Core i7 (I7-4770HQ).
Mine is a ME293LL (EMC 2674 late 2013) Core i7 2.0 (I7-4750HQ). Do you think it's okay anyway? I ordered a flash I should arrive this week, as soon as it arrives I will try. Do you think it is possible that it no longer starts because of the flash (only fans start)?
Thank you,
EdoardoLeave a comment:
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Re: macbook A1398 EMC 2674 no chime and black screen
The board number is 820-3662-aLeave a comment:
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Re: Need help for bios a1398 emc 2674 N25Q064A
820-3662-a c02m99bpfd56Leave a comment:
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Re: macbook A1398 EMC 2674 no chime and black screen
Thank you for your answer,
the flash is from the original card which was too damaged. I was able to read the chip with a programmer and it seems ok to me unfortunately I lost the chip of the board purchased as a replacement which was working before.
Tank you
EdoardoLeave a comment:
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Need help for bios a1398 emc 2674 N25Q064A
Hi is there anyone who can please check if this file is correct?
It is for a Macbook pro late 2013 a1398 emc 2674 with Micron N25Q064A chip. With this chip, only the fans start and the screen does not turn on and there is no sound. I can't figure out if the problem is something wrong with this file or something else is broken.
Please help me thanks.... -
macbook A1398 EMC 2674 no chime and black screen
Hi, I have a problem with macbook pro A1398 EMC 2674 (late 2013), after replacing ic Micron N25Q064A efi flash, it doesn't start anymore. when I press the power button the fans start, the screen remains off and makes no sound.
Could it be caused by invalid flash content? Have you ever had a similar problem? Any suggestions?
Thanks!
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