820-3115 - Hissing/ticking noise by the lvds connector

[Alan.L]

Power down with ac the noise is still there.

 

[Alan.L]

Ah bullcrap. Noise actually still there even with battery power off state. But noise is much quieter.

just to confirmed.

plug magsafe only, (noise present) board then auto power on, then i press power off switch (noise still present)


plug battery only (noise present) then i press power off switch (quiet noise)

 

[dukefawks]

So it comes from U7000 circuit. Bad U7000, resistors, caps, FETs, traces

 

[Alan.L]

definitely, quieter, the noise is still there but very faint noise. after power off with battery only.


u7000 has been replaced once. but caps, resistors and fets are original.


Q7085 (removed, noise still present)
Q7080 (removed, noise still present)
Q7030 (removed, noise still present)
Q7035 (removed, noise still present)
D7005. (removed, noise still present)

 

[Alan.L]

You powered it down from battery, this will not exclude U7000 circuit, so I still don't know if the noise comes from there. Power down with AC connected.

noise is still there after i removed Q7931

 

[Alan.L]

ok noise is gone after injecting voltage to the board.

it was L6995 lol.. i pretty sure replaced this couple of time.

now i get a steady 3.4v on PP3V42_G3H instead 3.5v.

 

[Alan.L]

sometime charger doesnt go solid green and doesnt turn on what could cause this?

when no green light =

PP3V42 - 3.47V
SYS_ONEWIRE - 3.46V
PPBUS_G3H =12.52V
ADAPTER_SENSE - 3.48v
PP5V_S5 = 5v
PP3V3_S5 = 3.32v


however turns on with battery all the time.


can a bad L6995 coil damage U6990 or ISL6259 even tho i replaced these 2 chips for 3 times already when trying to find the noise?