MacBook Air 820-2855 A

[Djsp]

Hi, I'm learning how to repair the macbooks, I'm working on a macbook air A1370, card 820-2855 A, the cold machine starts normally, at some point, has video artefacts, and then 3 beeps, I don't seem to recognise the twig, I don't know how to do it, because

 

[2informaticos]

First of all, welcome to the forum!

Looks like RAM issue.
You can try to reflow all DDR chips, gently tapping each one, to ensure good solders.
Reballing should be the best option.

Keep in mind, broken solders/traces under CPU can cause this symptom too.

 

[Djsp]

I thought the can, too, but the machine starts at the beginning is all normal, with another machine didn't read the twine from the beginning and he didn't go to video, but He starts, after something warm up, the problems started

 

[Djsp]

This is what I get, I don't know if I dedicate myself to cpu or to ram.

 

[2informaticos]

You can only try to reflow/reball RAM chips.
Unless you have necessary tools and skills to reball/change CPU.
However, first step is to go for RAM...