Ppbus_g3h

[john]

When I measure up in diode mode it give me 0.49
when i measure in V mode it give me 12.6 V and then slowly it's dropping.
What does it means?

 

[aprendiz]

It means it is failing.....lol

What board are you talking about???

 

[john]

820-2879-b

 

[aprendiz]

Check R7005, should be 20ohm...... Also remove F7040 and see if voltage gets stable on pin 1....

 

[john]

R7005 is 20ohm. removed f7040 measured at pin one i get 12.5V for 3 seconds and it goes down to 5V slowly and then back again to 12.5 and so on

 

[aprendiz]

Resistance between pin 17 and 18 and between pins 27 and 28 from U7000.....

 

[aprendiz]

Voltage on pin 2 from U7000 is stable??

 

[john]

16.52V stable

 

[aprendiz]

ok, what about the other question, resistane between pins 17/18 and 27/28...

 

[john]

17/18 - 2.87
27/28 - 19.89

 

[dukefawks]

Seems fine. Look around TPS51125 area, corrosion?

 

[aprendiz]

Replace U7000.........

 

[dukefawks]

Don't touch U7000 just yet. If U7000 is dead it should still power on from a battery that has a charge.

 

[john]

there's no corrosion around TPS51125

 

[john]

i have a green light in the charger and that's it. any thoughts on this?

 

[dukefawks]

No, connect a battery that holds a charge and see if it will power on.

 

[aprendiz]

Put back F7040 first of course....

 

[john]

i did connect a battery and still nothing...the F7040 is on the board

 

[dukefawks]

Check resistance to GND on L7220 and check voltage on R7273. Do this without battery and on AC, see if it pulses.

 

[john]

R7273 is 3.4V
L7220 1.71kohm

I was keep tracking where on the board it starts the voltage to drop and i find out on Q7085 at pin
1 i have 16.26V
2 is 16.26V
3 is 16.26
4 is 15.5 13.3 and 5.5V
5 is 16V then 15 14 13V its dropping to 4 ad so on like PPBUS_G3H