Macbook air with 820-3437-B extremely slow

[Francisco.s]

Hi, have a Macbook air with 820-3437-B with a weird problem.

It starts and seems to stop at the very beginning of POST, there is no chime and no access to usb boot pen-drive.

Current consumption is near 500 mili amps and seems not to do anything/

The weird issue is that if left it in this state "booting", the chime sounds about 4 minutes from start, and 2 minutes later I can see the pendrive led blinking and back-light is on. About 2 minutes more the progress bar starts, but in very slow motion.

It takes more than 30 minutes to show the logo screen. (I am using a windows boot pen-drive)

This board came to me with a new smc and I've tested a good clean dump for bios.

At first I thought that smc could be not from a correct donor motherboard, so I decided to update smc firmware.

So I use SMCTool_V1.0.7 to update the smc firmware and it took half an hour to do it.

After that nothing has change, the chime sound and POST are still extremely slow.

All voltages and signals seems to be in order.

Could be a re-branded smc or a damaged smc, what do you think?

Forgot to say that cpu temperature is normal and battery is original and ok.

[mon2]

Re: Macbook air with 820-3437-B extremely slow

https://boards.rossmanngroup.com/thr...ry-slow.51214/

[reformatt]

Re: Macbook air with 820-3437-B extremely slow

These boards will throttle the CPU when a sensor is missing or there is bad data (e.g. when the trackpad is disconnected/cable is corroded/bad). I've also had slow boots off a bad SSD too.

That said, it isn't normally that slow. ASD is available for this model, so might be worthwhile running it to check sensors etc. The problem with 2nd hand boards like this is you don't know what the last guy did to it.

I'd start off with a known good clean ME BIOS for this board and go from there.

[Francisco.s]

Re: Macbook air with 820-3437-B extremely slow

https://boards.rossmanngroup.com/thr...ry-slow.51214/

Thanks mon2, i've read the post at rossmanngroup.com and seems to be the same isssue.

I've tested the board with and without nothing connected.I will tray with external screen.

In the post mention the idea to change the smc, but is not clear if it was changed finally.

by the way, the smc version reported by MRI was 2.12f137, and before update with SMCTool is 2.13f15.

I want t thanks MuertoGB and P Daniels for this great tool.

[Francisco.s]

Re: Macbook air with 820-3437-B extremely slow

These boards will throttle the CPU when a sensor is missing or there is bad data (e.g. when the trackpad is disconnected/cable is corroded/bad). I've also had slow boots off a bad SSD too.

That said, it isn't normally that slow. ASD is available for this model, so might be worthwhile running it to check sensors etc. The problem with 2nd hand boards like this is you don't know what the last guy did to it.

I'd start off with a known good clean ME BIOS for this board and go from there.

Thanks reformatt, I've tested with no ssd connected, and also trackpad works ok, at least in boot selection menu.

I've tested a different bios dump and cleaned me region and pram with Medusa.

I will try ASD and let you know.

[Francisco.s]

Re: Macbook air with 820-3437-B extremely slow

I have managed to run ASD EFI 3S156 but can't run ASD OS 3S156.

It shows an error with Management Engine:

Chipset (test 1) - Management Engine Presence Test
-verifies the presence of the Management Engine.
ERROR-not found

Can't go any further showing more errors due to track-pad (or mouse) has a terrible delay.

I also run a linux distro from an external usb dvd drive, and it loads at a normal speed and runs smooth. (also trackpad is ok with linux)

I tried a win-10 install dvd but never ends loading. (progress bar gets stuck)

There are many references on internet about this error message but seems nobody solve the issue.

[Francisco.s]

Re: Macbook air with 820-3437-B extremely slow

It shows an error with Management Engine:

Still working with this Macbook, I'd manage to disable the "chipset test" and there are no more errors detected.

Something new occurred, now, doesn't work with a clean ME bios, it tries to start, but immediately goes to stand-by and takes only 20 mili-amps, but with the original bios newly programmed, boots but very slow as before.

I'm thinking that is not a problem with SMC, but a cpu/pch issue.

by the way, the smc version reported by MRI was 2.12f137, and before update with SMCTool is 2.13f15.

I wanted to say after update.

[mon2]

Re: Macbook air with 820-3437-B extremely slow

Still could be your bios.

See here:

https://www.badcaps.net/forum/showthread.php?t=47250

[piernov]

Re: Macbook air with 820-3437-B extremely slow

https://logi.wiki/index.php/ME_Disable_Strap

[Francisco.s]

Re: Macbook air with 820-3437-B extremely slow

Still could be your bios.

See here:

https://www.badcaps.net/forum/showthread.php?t=47250

Hi mon2, I've sent a pm to the author of the post, because it's not clear that bios solve the problem, and he says that bypassing chipset test, some more sensor errors were shown.

I bypassed chipset test, and no more errors were found.

Just in case I will reprogram a new dump.

[Francisco.s]

Re: Macbook air with 820-3437-B extremely slow

https://logi.wiki/index.php/ME_Disable_Strap

Hi piernov, I have tested the circuit of Q1920 and it works as it have to. (I think)

Pin 2 of Q1920, SPI_DESCRIPTOR_OVERRIDE_L, is high level and SPI_DESCRIPTOR_OVERRIDE_LS5V is low level, so SPI_DESCRIPTOR_OVERRIDE is low level or floating.

I've tested with shorting SPI_DESCRIPTOR_OVERRIDE to ground, and all is the same.

SMBUS_PCH_CLK and SMBUS_PCH_DATA has good dc level but no pulses. (R5300, R5301) (have nothing connected to the board)

All I2C signals in page 40 have good dc level and pulses. (except the above mentioned)