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

[dukefawks]

Looks like just a bad fan to me. That noise is an inductor/coil. Usually when you put pressure on the noisy coil the pitch will change. See if you can locate the coil that is making the noise, there are only 3 big coils near the LCD connector.

 

[Alan.L]

noise is coming from multiple locating, near the lcd connector and near the usb ports.

 

[dukefawks]

Find the coil......go over them one by one and put some pressure on them with something sharp/hard, finger won't work.

 

[Alan.L]

but fan is working on other machine perfectly.



edit. actually after replacing U6990, Q7030, Q7035. i dont have dim green light anymore. not sure if this is temporary or permanent fixed.

but now, sometime it get a green light and fan doesn't spin and no post.
and sometime green light, fan spin and post.

is it power problem or sensor problem, maybe it want to post but something preventing the fan to spin?

ASD passed all test.

 

[Alan.L]

mm, i can turn on the board without a fan attached. is this right?

 

[Alan.L]

i poked u9330, it got piping hot. i only notice the heat after i pick up the board by usb port.

it has not crack when i looked under microscope. external display are working before poking it.

 

[Alan.L]

ohhh other side of the board, which is under u9330,
the u9410 looks like it has erupted.

 

[dukefawks]

Thunderbolt circuit. Fuck that shit and rip if off, don't waste time trying to fix thunderbolt the board works fine without.

 

[Alan.L]

this cant be causing no fan spin and also i can turn on the board without a fan attached. is this right?

 

[dukefawks]

Fan or not will not matter. Remove the fucked chip and get another fan.

 

[Alan.L]

i dont have another fan in stock. i will come back to this board someday..next week.

 

[Alan.L]

managed to obtain a replacement fan.

i;ve removed both u9330 and u9410. hissing noise is still present. maybe i poked u9410 little too hard caused to explode.

still sometime will not switch on, can it be bad smc ?

 

[Alan.L]

i;ve removed L9701, L3895, L7770, L7700 L7100, L7630 and noise still present.

have a listen.

lol... just remember i had one of this stethoscope in storage.

.
i think the noise is coming from Q7070 , Q7630 or Q7085

 

[dukefawks]

Let the board auto power on and shut it down with the power switch. Is the noise still present when the board is in this off state?

 

[Alan.L]

Yes.I'll remove these 3 components once i get home.


duke, how come forum search doesnt work when i type eg. 820-3115

 

[dukefawks]

Cause of the "-" symbol. 3115 is unique enough to use.

 

[Alan.L]

damn, i'am still stuck

duke, is there a way to turn off a rail. i want to know which rail the noise is coming from.

maybe i should give up

 

[Alan.L]

Let the board auto power on and shut it down with the power switch. Is the noise still present when the board is in this off state?

if i power on with a battery then shutdown with the power switch, the noise goes away.

 

[2informaticos]

If noise is not present in S5 state (with charger), pull out Q7931 and listen if appears again.

 

[dukefawks]

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.