Repair Samsung (WAM551/WAM550) M5 Multiroom speaker

[Tony.T]

I have a problem that the speaker does not start.
When i probe this component..

http://www.gmt.com.tw/product/datasheet/EDS-2992B.pdf

sop 8.

on pin 5...6..7...8....

there is 3.8V...then suddenly a buzzing sound is heard ....and the voltage drops down to 0 V. Efter 2 seconds...it stops...and the voltage rises up to 3.8V again.
it seems that this component has something with eeprom chip to do??...

any ideas what to search for more?  what the problem could be? Shortcut in eeproom? faulty eeprom? or this component?  Don't know what purpose it has.

I also thinking that the main cpu...attached picture...maybe starts to boot but somehow reset it self every 15 seconds (time between the buzzing sound and voltage drop).  As it is BGA chip...maybee one should try to reheat the chip to resolder the bga points?

The black ring shows where the EDS-2992 chip is located on the other side of the PCB.

Anybody with schematics for this PCB?

Datasheet for the sdp1207???

Thanks for any possible input that can point me to any direction ....

[Tony.T]

Ok....lets put in some more data.

Here is a picture of the cpu...and the flash memories. When i plug in the white socket cable (capacitive buttons on top of the picture) the CPU starts to initiate i think...and then reboots is my guess?  When the cable is unplugged i can not hear any strange sound and voltage drop.
When i measure on the 3.3V...and 5Voltage points on the pcb...everything drops to 0 volt every 9th second.  And is zero in 1 second and then normalized again to 3.3 or 5V.  and that is on every point there is after the buck converters that converts from 14 to 5 or 3.3 V....or any capacitor etc.  It is as the CPU resets everything and shorting it to ground.??

I will also attach a soundfile that you can hear how it sounds when something happens and the voltage drops to zero. (The 14V input is ALWAYS stable)....and there is 4 buck converters on the PCB and it is the same on those....after the converters the voltage drop is present every 9th second.

[Tony.T]

The soundclip aswell....  the silence between the voltagedrop is 9 seconds....in the clip i have shortened the time.  4 times in this soundclip the voltage is dropped.  I had the phone microphone directly on the samsung chip on the picture posted before this.

[Rasz]

maybe it boots and at the end enables Audio amplifier and thats where the short is

[Tony.T]

hmm...interesting idea ...  yes, could be that it is a shortage that is activated when the processor initiate it.  i have tried to find the service manual/schematics but it is impossible. That should help me to see where the amplifier part is....

[danikd]

HI, any solution, has one with same symptoms. many thx for info. Daniel

[mopk47]

My M5 is rebooting every few minutes. Is there any info available? Cheers