820-3115 blinking greenlight

[PhilipC]

Liquid damaged dotted around the board

C7526 & C7525 we're burnt to a crisp when I got it replaced them and it cleared the short on that rail
Replaced ISL and ran a jumper from ISL pin28 to c7020. current sense resistors all measure ok.

G3h 12.59v

R7005 checks out
L7260 600 ohms to gnd
L7220 600 ohms to gnd

pp3v3_s5 3v
pp5v_s5 0v - 4Mohms gnd

Any ideas?

 

[dukefawks]

5V_S5 really 0V or you mean 5V_S3? EN pin on U7200 high?

 

[PhilipC]

yeah 5v_s5 is 0v i measured at c7273

p5vs3_entrip is 0v
p3v3s5_entrip 0.7v

edit: just measured c7273 again and now seem to be getting a fluctuating value 1.3-5v

 

[dukefawks]

SMC_PM_G2_EN stable?

 

[PhilipC]

stable at 3.46v

 

[dukefawks]

SMC_PM_G2_EN makes 5V3V3_REG_EN and enables both 3v3 and 5V LDOs from U7200. So if both signals are there the LDOs should be working or U7200 is dead.

 

[PhilipC]

5v_s5 is now stable, replaced isl and still same symptoms

 

[dukefawks]

Why did you replace the ISL? Why is 5V_S5 stable now? If PPBUS is 12.6V then 3v3_s5 should be present too.

 

[PhilipC]

I mean 7200 sorry, 3v3_s5 is present and stable but still no 5v_s3

 

[dukefawks]

Voltage on C1802/03?

 

[PhilipC]

both at 3.4 stable

 

[dukefawks]

Check for short pulses on 5V_S3, best to do with scope, multimeter are to slow. Also check 32KHz from clock chip and crap under SMC.