New Posts  All Forums:Forum Nav:

Latitude C640 won't boot

post #1 of 6
6/6/08 at 12:08pm
Thread Starter 
My latitude won't start. If it has been sitting for a while it will start to boot, even show the windows desktop for a few seconds, then shuts off. If I try it again right away, it will shut down sooner. The battery is good, the fan runs, the heat sink is clean, and I have reapplied heat sink compound to the CPU. To me, it acts like it's overheating, but why? Periodically, it tells me that the system time is not set suggesting that the BIOS battery is dead. But would that cause it to not boot?
Reply
Reply
post #2 of 6
6/7/08 at 12:50am
set the time and date and see ifit boots!
Reply
Reply
post #3 of 6
6/7/08 at 4:03am
It could possibly be the DC Power board. These are prone to going out and are easily and inexspensively replaced. It may be that once the DC Power board heats up something expands and a circuit is broken or a thermocouple shuts the whole thing down.
Reply
Reply
post #4 of 6
7/4/08 at 5:29am
Hi
Replace U45 transistor
Good luck
Reply
Reply
post #5 of 6
7/4/08 at 8:38am
Quote:
Originally Posted by rupertbear View Post
Hi
Replace U45 transistor ...
pics, and some instructions?

cheers ...
Reply
Reply
post #6 of 6
7/4/08 at 11:45am
Hi
Afraid motherboard has to be stripped down to get to U45. Having stripped down board with no ram or harddrive or anything plug psu in.Keep finger on
U 26 and see if it gets hot.U26 is a micropower regulator that supplies power for the power up circuitry.It lives under vga socket with number M5236-3.3BM.Pin 3 is output and should sit at 3.3V .Any voltage lower than that indicates a problem with U45.U45 is 70mm due north of U26.
good luck
Reply
Reply
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Dell Notebooks - General