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Macbook A1989 820-00850-A No boot

S

sourcensolutionsonline@gm

Member
Hello ,

I got this Macbook A1989 was previously water damaged and was repaired by me , last week the owner brought it saying that its not charging and not booting , so I have checked it and on my AMP meter i am getting 5.09V , 1.01 watts and 0.20 amps . So I proceeded to open it and take a quick look inside and all was looking fine .So I pulled out the board and connect my amp meter and placed the board under my thermal imager and found that U6903 was getting super hot , so I ordered U6903 on eBay since i did not have any donor boards here to harvest it from , I received the chip on Friday and I installed it Yesterday and the behavior did not change . Since after I changed U6903 with the new chip that I ordered U7800 and U3900 The T2 along with U6903 they get hot but still no 20V on my USB amp meter and no boot , I have checked all the CD3215 Chips and I have even changed the whole 4 of them which I did not even have to but did it just in case , now I m wondering if my U6903 new chip can be bad as the seller would allow only one chip per order so i was able to get only one chip of U6903 . PPBUS_G3H is Present.

Please Help me out.
 
2informaticos

2informaticos

Administrator
Staff member
Changing a chip because geting hot???
Usually heats because of overcurrent, caused by OTHER component.

Didn't even check its output voltage?
What about diode mode to ground at 3V3_G3H_RTC?
 
S

sourcensolutionsonline@gm

Member
I forgot to mention that , That was the first thing that I did , 3V3_G3H_RTC before I removed the chip was short to ground Diode mode was . then as soon as I remove the chip the short was gone then after I replace the new chip 3V3_G3H_RTC in diode mode was 0.311 and measuring 3V3_G3H_RTC voltage i am getting 12.28
 
S

sourcensolutionsonline@gm

Member
I have another good board the same type also when i measured 3V3_G3H_RTC I am getting 12.65V, I wonder if my new U6903 that I ordered on eBay is working. Any other suggestions?

Thank you very much.
 
2informaticos

2informaticos

Administrator
Staff member
No idea how can you get such voltage on 3V3_G3H_RTC.
Did you really check on correct point?
What about L6900/01 voltage?
 
S

sourcensolutionsonline@gm

Member
I was also shocked too as i was expecting 3.3v there and that was why I got my known good board to compare voltages and the good working one was giving me 12.65V

L6900 and 6901 is giving me 3.373V
 
S

sourcensolutionsonline@gm

Member
P3V3G3HRTC_FB = 0.869V

P3V3G3HRTC_SS = 0.869V

I am going to rerun the voltages again , but I am having a very strong feeling that my U6903 that i got from Ebay maybe is not a genuine chip , I don't wanna pull it from my other good working board as I keep them to compare voltages when they come in with problem , On rossmangroup store t U6903 is not listed , do you have any other suppliers where i can get those from and Quick?
 
2informaticos

2informaticos

Administrator
Staff member
"L6900 and 6901 is giving me 3.373V"
What's the problem then, why do you want to change U6903 again???
Isn't 3V3_G3H_RTC coming from these coils?
I cannot understand how do you got 12V before...

PLEASE, try to understand a schematic and post ACCURATE information.
We can't help if your replies are "out of range"...
 
S

sourcensolutionsonline@gm

Member
Ok , Sorry If I did not clearly express that but 3V3_G3H_RTC and PP3V3_G3H_RTC_REG_R to me they are two different power rails from my point of view ,

And I can see L6900 and 6901 is connected to the power rail PP3V3_G3H_RTC_REG_R is providing 3.373V , but the 12.28V that I mentioned in my earlier message is coming from PPVIN_G3H_P3V3G3HRTC_R . I am going to post of the diode mode and voltages of U6903
 
2informaticos

2informaticos

Administrator
Staff member
Don't bother anymore with U6903 if you indeed get correct 3V3_G3H_RTC.

All AWAKE and SLPS2R voltages present?
Check LDO voltages for CD3215 chips.
 
S

sourcensolutionsonline@gm

Member
All AWAKE and SLPS2R voltages is present and normal

When I Check LDO voltages for CD3215 chips. I found U3100 , 3200, as well as UB300 PP1V1_UPC_XA_LDO_BMC 0.000, without voltages while all the other voltages are present , that same PP1V1_UPC_XA_LDO_BMC diode mode reading is 0.486 However at UB400 PP1V1_UPC_XA_LDO_BMC is present and normal , Help me to proceed please.
 
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