MBX247 water damage

[Bisketti]

Hi I need some help with this one I have a Sony Motherboard MBX-247 it has very small amount of water/liquid damage. on the KBC and few surrounding components. I replaced the KBC and lifted the coil PL13 on the 3.3v line as theres also a short farther down on the +3vpcu line . But fir the moment I am trying to get 3.3v from pu9 (PM6686) but not getting output. I have replace this chip with new one also.
So I get
Pin1 ref 1.8v
Pin2 Ton 0v
pin3 vin 4.9v
pin4 enldo 4.9v
pin6 vin 19v
pin7 ldo 4.9v
pin27 en1 4.9v

Any ideas why Im not getting 3.3v out?

[dj_ricoh]

Re: MBX247 water damage

every thing its ok on ISL88731?

[Bisketti]

Re: MBX247 water damage

every thing its ok on ISL88731?

Looks ok , is there anythin in particular I should be looking at. Im stumped .I cant figure out why there no 3.3v output

[hazardus]

Re: MBX247 water damage

If you have a scope check the signal on Pin 23 and 25,26 at PU9.

[Bisketti]

Re: MBX247 water damage

Thanks for the input. So basically the pu9 3.3v wont output until the coil is in place due to the feedback loop I presume because I re soldered PL13 and then then bench supply returned to switching on current limit and going back into the loop. I then removed pq45 and pq44 and the 3.3v retuened to pl13. bo if I now put 3.3v into either of the +3v (pq45 pin1) or +3v_s5(pq44 pin 4) the the overcurrent kicks in. So basically Im looking for a fault common to both lines.

[Bisketti]

Re: MBX247 water damage

I have also found that pl8 (+1.05v) has a short on that line also. When I lift one side of Pl8 the short on the regulator side isnot prsent so is further downstream on the +1.05v line.