Another 820-2610 No green light

[Bohmmen]

No green light with this board.
I have replaced bad C7771

Board looks very nice and clean!

PPBUS_G3H 8.4V
PP3V42_G3H 3.41V

ISL6258
14 ACOK 3.2V
2 DCIN 16.5V
3 ACIN 3.95V

 

[dukefawks]

Did it have a green light before messing with C7771?

 

[Bohmmen]

No, it had not.

 

[Bohmmen]

C7771 was 0.3 volt before replace. Now it's 1.1 volt.

 

[dukefawks]

Usually fried Q6910 and U6915, happens if you don't line up the magsafe correctly with it out of the case. Check voltage on pin 5 of U6915

 

[Bohmmen]

pin 5 u6915 0volt

 

[Bohmmen]

it boots when battery is plugged in. I have five 820-2327 boards that acts exactly the same way, works with battery but not with charger

 

[dukefawks]

Pin 5 should have 18V or so. Check pin 2 of Q6910, it should be 9-13V. If that is ok, replace U6915 and Q6910.

 

[Bohmmen]

Having a hard time finding Q6910. They can be found on 820-2330 and 820-2390. I Don´t have any of these boards. Need to order from ebay and wait 30 days.

 

[dukefawks]

You can use a NTZD3152 for testing. It's a bit at it's limit as it is rated for 20V.

 

[Bohmmen]

Ok, thanks.
I have a couple 820-2879 boards but I don't want to steal anything from them until I tried to fix them.
I will probably spend a lot of time at this place, reading threads and learn troubleshoting

 

[Bohmmen]

Does any of these two components, Q6910 and U6915, work without the other. It's always a risk when you take anything from a donor board that the component doesn't work.

Do I get 9-13volt on pin 2 of Q6910 if U6915 is bad?
Do I get 18 volt on pin 5 of U6915 if Q6910 is bad?

 

[dukefawks]

Replace them together to avoid wasted time. It is U6915 that shorts and then kills Q6910.

 

[Bohmmen]

got U6915 and Q6910 today. Replaced both but still no green light.
pin 5 u6915 0volt

 

[dukefawks]

Voltage on R6910?

 

[Bohmmen]

Pin 1 voltage is changing between 16.71v and 16.85v
Pin 2 voltage is changing between 15.97v and 16.09v
Pin 6 0volt

 

[dukefawks]

I asked R6910...

 

[Bohmmen]

sorry, R6910 is 3.24 volt

 

[dukefawks]

ok, voltage on pin 2 of Q6910?

 

[Bohmmen]

Q6910
Pin 1 voltage is changing between 16.71v and 16.85v
Pin 2 voltage is changing between 15.97v and 16.09v
Pin 6 0volt