820-3787 green light appear every few second

[Yoel Ren]

I have this 820-3787, my own board who died a long time ago, time to repair it
when I plug in magsafe, it there's a green light but only a momentary, and it would appear a few second later, im using a magsafe 2 85w
is there any chance the problem is still my magsafe ?
I don't have pp 20v at the fuse, tried changing dc in already

 

[2informaticos]

Probably original charger detects leakage and doesn't want to power up the board.
Usually Q7180, or D7010 issue.
Post exact value of R7012; ohm scale, measured onboard.

Does it start with desk power supply, or fake charger?

 

[Yoel Ren]

q7180 and d7010 looks fine though
R7012 measured by probing each end is 22.06k
sorry no access to desk psu and fake charger..

 

[2informaticos]

"q7180 and d7010 looks fine though"
What this means, are they photogenic?
Do you have a DMM to check them???
Post exact ohm value for R7180/81 and R7185/86, measured onboard.

 

[Yoel Ren]

Im sorry to ignore the question, but I have 1 other board 820-00138a which is 2015 15" retina I think, so the magsafe doesnt turn on at that board too, my magsafe is 85w, but, I heard from rossmann videos if the cable is from 60w, is it still doesnt work ? if its, I will find another real magsafe 2 85w first..

 

[2informaticos]

You should get G3H and S5 voltages at least; even with 45W charger.
And board should charge battery and start with battery and any charger connected.

 

[Yoel Ren]

So changing q7180 give me steady green light, but im such an idiot, i remove the smc and accidentally mixed it up with other smc, so i want to ask, if I try to test smc 1 by 1, how can I know if the smc doesnt match? Any measurement i can make?

 

[2informaticos]

You must be sure to get SMC from same board model.
You can test all SMC one by one, untill get fully working board; supposing original SMC is good.

 

[Yoel Ren]

so I place this smc, It give me green and then amber light, i try usb mouse and i got usb activity , and then i hooked it up to external monitor and I have an image, booting fine, should i troubleshoot no video problem or this can be wrong smc ?

 

[Yoel Ren]

Sorru, just bad screen

 

[Yoel Ren]

Hi, i just realize this board doesnt have serial number ( clock set right, active internet connection). I have been told to use hex editor, but I don't really know how, any tutorial on changing serial number?

 

[2informaticos]

Many threads on the forum for the same issue.
You should got an idea already.
Replacing Fsys area into another (clean ME) BIOS, with the one from your backup BIOS, should solve the problem.

Upload your backup somewhere; if you cannot do it by yourself.

 

[Yoel Ren]

I have tried reading fsys from original bios to medusa but i got an error when trying to write fsys to new clean me bios. The problem is i want to learn how to edit serial number, in case the original bios is gone, after that i will fix checksum with the medusa

 

[2informaticos]

If you just swap entire Fsys area, no need to fix checksum.
Original serial number of the board is preserved.

If you need to change serial number, do it with HxD editor.
Then fix checksum, after BIOS has been flashed on the Mac ROM.