820-3209-a no green light.

[Sr. Robot]

Hi, i have an 820-3209-a with loads of corrosion. Theres no green light and PP3V42_G3H is not present.

Replaced C7121, R5250, R5251, C7103, C2453, and Q2815

Diode mode on PP3V42_G3H is 0, but nothing seems to be getting warm

 

[2informaticos]

Start posting Q6910 voltages.

 

[Sr. Robot]

PPDCIN_G3H_ISOL : 14.98 v

DCIN_ISOL_GATE_R: 6.7 v

PPDCIN_G3H: 14.98 v

 

[2informaticos]

Now post U6990 voltages...

 

[Sr. Robot]

P3V42G3H_FB: 0.6 v

PP3V42_G3H: 0.5 v

P3V42G3H_BOOST: 1.8 v

P3V42G3H_SW: 0.6 v

PPVIN_G3H_P3V42G3H: 14.15 v

 

[2informaticos]

Do you get 14V at both 6 & 8 pins?
Check/replace R6995/96; C6995 can be removed.
Post first EXACT diode mode to ground at L6995; not sure if you meant 000, or OL.

 

[Sr. Robot]

Yes, 14v at both pins.

R6995/96 are looking good and resistances are 127kohms. Removed C6995

L6995 diode mode: 0.000

 

[2informaticos]

So you have short to ground at 3V42_G3H; very good reason for NO voltage.
Lift L6995 and see where the short remains.

 

[Sr. Robot]

Removed L6995.

Pin 2 is 0.002 now

Pin 1 is 0.237

 

[2informaticos]

Then use voltage injection method.
Start with 1V, no more than 4V.