need help Board start only when its hot ??

[Richi_el]

Hi @ all
i have machine and some problems with it...

the board is from a machine and has a typical problem..
sometimes it starts and sometimes not..

allways when i heat the the board with a heater gun it starts.

ive tried many things ... but i didnt find out whats the reason..

Pic 1 is the whole board in top view

Pic 2 is the whole board groung view

Pic 3 is the a part of board (power supply 13V + 2x 5V)
mostly i heat this part of board an it works

Pic 4 is the same part of board in bigger view

pic 5 is the ground view of this part of board in bigger view


so maybe someone has some informations for me please because iam also a newbie in this and dont know all parts..

can someone find any thermic elements on this board ?
is the lc244a on pic 5 maybee a reason ???

please help

[Richi_el]

Re: need help Board start only when its hot ??

TOp view

[Richi_el]

Re: need help Board start only when its hot ??

Ground view

[Richi_el]

Re: need help Board start only when its hot ??

PIC 3 Power supply

[Richi_el]

Re: need help Board start only when its hot ??

Pic 4 Bigger view

[Richi_el]

Re: need help Board start only when its hot ??

pic 5 bottom side

[kasfamily]

Re: need help Board start only when its hot ??

1- pic3 U101 badly soldered. 2-Should be localized using a thin nozzle for heat gun

[Richi_el]

Re: need help Board start only when its hot ??

Edit :

Mosfet u101 is reworked now---> same problem...

But

Today ive desolderd bga in pic 1 and the board start aswell without any heating process.

It seems that the problem is by bga ..its a via but wich one ?
Is someone able to tell me the correct type of it ??
I cant find this bga on google or somewhere else....

I works in combination with the bga on pic 2 via cx700 ....

[Richi_el]

Re: need help Board start only when its hot ??

I have to cancel my last post , also the same problem without bga ....
It seem to be a thermal problem...

This i bga wich ive disolderd

[dragos2009]

Re: need help Board start only when its hot ??

that is a via c7-m processor 1ghz/400mhz fsb http://www.cpu-world.com/CPUs/C7-M/V...obileBGA).html