Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

[marce002]

Hi all

I have a A1425 for a motherboard swap because the SMC burned. I have replaced motherboard but showed up lock screen, then replaced efi chip and started ok with some strange screen issues, then it is only turning on with chime, fan spinning and backlight (noticeable signs of backlight working and back screen apple hole is lit) but no image, so i assume brain is ok, backlight is ok but no image.... that sound EFI to me, no signs of usb drives activity but 5vol is present and also keyboard caps not working and not able to select boot options.... is this a clear EFI issue that needs to be firmware fixed?

thanks in advance...

PD
note a little hot, but replaced thermal paste, and remember
new mother was working for 3 or 4 minutes , with strange screen behaviour as i mentioned, and stopped working after a smc or nvram reset i think.

[marce002]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

forgot to mention: it does show the NO BATTERY screen blinking, when battery is almost empty.. clearly no screen / backlight issues. just need to know if im ok with the feeling that:
as using a Bios chip from another board, need to reprogram a new chip with a Clean ME region , if so i would look in a thread with this subject involved. thnks for an anw\swer

[marce002]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

please any one?

the situation is this:


I have bought an used 820-3462 motherboard on an ecommerce site: mercadolibre/.. is like ebay, I replaced my old motherboard (burned SMC) with this one, but realized it was pin locked with 4 codes.. i cant return it so replaced the efi chip with my old motherboard but still not working fine... downloaded a dump replaced my own serial but still no luck... it shows a blinking folder but as soon as i assemble the whole mac it will go to black screen (only chime)... and this is driving me crazy because i did solder and desolder the efi chip 12 times!!! trying different options and dumps ... I do not have raspberry, only a simple ch34a which flashes ok on the dump, that is not the issue. The problem is that whatever firmware I place on it after 2 or 3 restarts or connecting everything, it goes to chime and black screen of death (backlight present though).. WHAT I'M doing wrong?


thanks in advance!!


PD i have original dump (and more that 12 modified versions that i have already tried..) in original the ME ANALYZER shows:

Firmware: Intel ME
Version: 8.0.4.1441
Release: Production
Type: Region, Extracted
FD: Unlocked
SKU: 1.5MB
VCN: 2
PV: Yes
Date: 06/03/2012
FITC Ver: 8.0.4.1441
Latest: No

[SMDFlea]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

With some models a good full working battery is needed for the machine to boot, i don`t know if this is one of them. If you want the bios cleaning post your original backup in the bios requests sub forum - https://www.badcaps.net/forum/forumdisplay.php?f=40

[marce002]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

thanks a lot, nop it did not make a difference with battery connected... as soon as i try with a new flashed efi it gets overwritten by the system and it will not boot of course, sometimes chimes but most of the time does not (it depends on the flashed firmware), but never gave video again.... yes i will post the very first locked firmware for someone help me HERE...
A1425
820 3462
EMC 2557
ME 8.0.4.1441

[mon2]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

Have you tried a PRAM / SMC reset ?

Do you ever see the Apple boot logo ?

Can you test with an external video adapter ?

Does the caps key LED toggle after a 'normal boot' ? If yes, then the OS has booted.

[reformatt]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

These boards should boot out of the chassis without a battery connected. Do you have a Chipmunk USB tester and a way of measuring the Magsafe current?

The Chipmunk is a great way of quickly determining if the board is powered on, and the green flashes indicate the port is being probed for something to boot off. If your system had POST'ed and you see green flashes, you know it's likely a display problem. It's well worth the investment if you work on boards a lot. Failing that, you could use one of those USB sticks with LED on them.

I have a USB-C 85W charger, Uni-T USB-C meter and USB-C to Magsafe1 or 2 cable. Current here gives you a good indication on how the board is behaving. Variations in current up and down usually indicate whether there is CPU activity or not.

I think I have an A1425 kicking around my dumpster pile for an SPI dump. Nobody wants them when the anti-reflective coating is worn off.

[reformatt]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

So the board I have here boots fine on the bench with no battery. Initial current via Magsafe is 800ma, but then alternates between 440ma to 550ma when its probing the USB port to boot (this is without fans connected).

Firmware version is 429.0.0.0.0 from last Catalina update. I did take a dump of it if needed. Did a clean ME for it to test it out, but when trying to put it back on, had some issue with getting the chip to erase. I think this chip has some registers to prevent erasure according to the datasheet (BP0~BP3). So make you are indeed erasing the chip prior to rewriting it.

[marce002]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

thanks to all,,,, this is really a nightmare... i have tried mon2 hdmi, smc and pram reset with no luck because this is not detecting chipset or not completing POST I think.... so no caps lock because no os loading at all... only chimes with my original bios and black screen. If I try the bios tham came with the motherboard not even chimes. Always backlight present. only difference is chime with my bios (the one that was on my burned smc board) and nothing with the bios that came with the mother I have bought. Remember that the first time it did a lock screen , when i swap the motherboards, then put my chip efi with no edit at all, and showed up a 4 pin lock.... after that situation 12 or 13 instances of new bios attemps only logo , then only chime, and no image... but i know this is an efi issue or me regios or related to a lock.

i have tried TO SET A CLEAN ME (Management Engine) REGION IN APPLE EFI because:

it will boot, chime, but stays on a black or white screen and doesn't even reach a loading bar. i have posted the bios in the forum, maybe someone can unlock it, and also soldered wires to the board in order to flash efi 20000 millions of times with out removing the EFI and works fine, because c6100 was missed in one of the procedures and is lost and havent replaced yet, is a very tiny one in the efi chip area, as it is a gnd one did not replace yet. i want to fix this board . thks to all for any clue

[marce002]

Re: Macbook A1425 820-3462 chimes ok backl ok no picture EFI?

end of issue. was webcam / cable problem. disconnected and working