[SOLVED]820-00426 In S0, No Power

brunomotter

Member
Hello. Got an 820-00426 board here. No liquid damage, board looks perfectly fine, no corrosion at all and nothing getting hot. I get all voltages from page 84 up to PPVTT_S0_DDR. From that down the list nothing is present. PP1V05_S0 is reading low. It starts at 0.1V and goes slowly up to around 0.35V, jumps to 1V and goes back to 0.4V where it stabilizes. Looks like something is dragging it down. I'm suspecting bad PCH, but want to be sure before sending this back to costumer as I don't have proper equipment to replace that chip. Any hints?
 

2informaticos

Administrator
Staff member
Check first diode mode to ground at L7630; compare with similar board.

Post U7600 voltages; pins 3, 13, 14.
Check/replace R/C7630.
 

brunomotter

Member
Diode mode on L7630 gives me 0.074, unfortunately I don't have similar board to compare.


U7600:

Pin 3: 0.380V
Pin 13: 5.03V
Pin 14: 5.03V

R7630 is 0 Ohms as expected
C7630 is looking and measuring good with no shorts... Will replace it anyway
 

brunomotter

Member
I replaced C7630 and now it's different. PP1V05_S0 stabilized at 1.05V but still no POST

U8180:

Pin 1 - 3.3V
Pin 2 - 3.3V
Pin 3 - 0V
Pin 4 - 3.3V
Pin 5 - 3.3V
 

2informaticos

Administrator
Staff member
No need to check U8180 anymore, once you've got steady 1V05_S0.

Do you get voltage at L7430 and L7870?
Also check L7310.
 

brunomotter

Member
Somehow U7200 solder was crappy. Reflowed it with a lot of flux and board worked again! Thanks for all the help. Can mark this one solved!
 
Top