(347) 552-2258 [email protected]

00165 ppbus stuck at 4v

Patricia

Patricia

Member
Hi to you all nice people , Merry Christmas first of all :)
Got a 820-00165 board with no liquid damage or corrosion whatsoever. Had a short on C7430 , replaced it and ppbus went up to 4v (from 0 )
now the board is taking 23 mA and i am stuck :) pp3v42 is ok and i do have green and orange light .
Measured around the U7100 and pin 1 is 0 V , that cant be ok .... so traced back to R7185 and R7186 and they are up to specs .... The voltage there is probably not ok though , on pin 1 R7185 =18.51 and pin 2 =7.51V and the R7186 pin 1 =7.51 and pin 2 = 0 V

The Q7180
pin 1 and 2 = 18.51
pin 3 = 7.51
pin 4 and 5 = 17.95
pin 6 = 17.79

if you had this board would you replace the isl or q7180 ? :)

Thanks in advance
 
2informaticos

2informaticos

Administrator
Staff member
Merry Christmas too!

Q7180 looks good, as you get correct output voltage.

Post exact resistance between pins 17/18 and 27/28 of U7100.
Be sure C7125 is good.
Also check R/C networks from pins 5, 7, 8.
You may need to replace Q7130.

Check R7150 voltage, removing F7140.
 
Patricia

Patricia

Member
Hi 2informaticos
thanks for your reply

resistance between 17/18 is 3.3 Ohm , resistance on 27/28 is 20.2 Ohm
voltage on R7150 when F7140 removed is 8.58 on all pins
Voltages on Q7130
1 = 9.7V
2, 3 ,4,9 =17.94 V
5,6,7 = gnd
8 = 0.6 V
10 = 8.57 V

the only thing that shows any sign of heating up on thermal cam is the U7100 ( up to 30 celsius )

thanks again for your help
 
2informaticos

2informaticos

Administrator
Staff member
If you get 8.58V at R7150 removing F7140, then no problems on U7100 area.
Resolder F7140 and post diode mode (both directions to ground) at PPBUS_G3H.
 
Patricia

Patricia

Member
Jesus do i feel stupid ..... I DID check it in the initial stage and it was still ok :) guess it said goodbye during the reparation :)
What can i say besides thank you a thousand times !!!
mark it as solved :)
 
You must log in or register to reply here.
Top