820-00850-A - Tries to turn on and restarts

[2informaticos]

I'm sure you can find many videos on Internat about CH341 and that 1.8V adapter.
I use different programmer anyway...

 

[mushr00m]

I just bought another 1.8v adapter and the behavior is the same itself.

It gets a bit hot on the 1.8v IC thing
But still error detecting the eprom

What could it be? The black board itself?

 

[2informaticos]

Do you get 1.8V at pin 8 of your chip (on the black board)?

CH431 may not recognize the chip correctly.
In such case should show some unknown ID, not all 00.

Did you test with normal SOP-8 1.8V SPI chip (without black board)?

 

[mushr00m]

There is 1.8V @ pin 8 on the black board

Its gives these images

I do not have any SOP-8 1.8V SPI chip to test without blackboard.

Since it has 1.8V on pin 8 do you think the black board is damaged?

 

[2informaticos]

Test at least if your CH341 detects and read/write a normal 3V SPI chip.

 

[mushr00m]

Yes CH341 detects read and write an A1278 bios

image attached

 

[2informaticos]

Now try the same chip soldering into the black board.
Don't use the intermediate 1.8V adapter in this case.
If works, you have a problem with that adapter.

 

[mushr00m]

It worked perfectly using the black board it read and write

I put everything back and still same error.

Is there a way to buy a brand new BIOS and to program it to this computer?

I think this BIOS is trash

 

[2informaticos]

You can find it on Aliexpress, eBay and many other online stores.

 

[mushr00m]

Searching for 820-0050 BIOS only results for CH341 and alike. How to find the IC on Aliexpress? U4770 also didn't return anything

 

[2informaticos]

U4770 has no code marked on your schematic???
Did you try searching for MX25U3235F?
Be aware to choose correct package, WSON 3x4.

 

[mushr00m]

With a brand new can I make the macbook turn on again and back to life?

 

[mushr00m]

https://es.aliexpress.com/item/1005002748887534.html?spm=a2g0o.productlist.main.1.58082172zg5RKK&algo_pvid=76975dd5-cc05-4821-b801-fccf57337b77&algo_exp_id=76975dd5-cc05-4821-b801-fccf57337b77-0&pdp_ext_f=%7B%22sku_id%22%3A%2212000021955805261%22%7D&pdp_npi=3%40dis%21BRL%2141.03%2141.03%21%21%21%21%21%40211bc2a016789098976667141d06f3%2112000021955805261%21sea%21BR%21166226339&curPageLogUid=MlyjuoJWIE2k

Going to buy this one!

 

[2informaticos]

Flashing correct bin, you should go trough DFU and recover the machine.

 

[mushr00m]

Can I buy from that link is that the correct chip right?

I will follow flash procedures when it arrive!

 

[2informaticos]

Yes, correct.

 

[sekidata]

I just bought the identical setup as above for flashing T2 ROM chips. Can you recommend a MacOS app that will work as a CH341 USB Programmer?

 

[2informaticos]

I use Windows...

 

[sekidata]

Thanks. Will use Bootcamp then, no problem. What's a good source for clean SoC ROM bin files? Or would you recommend reading ROMs from a known good board instead of downloading them?

 

[2informaticos]

We have several SoC ROMs posted on the forum.
And still provides more, when needed...