Hello All,
I have a query related to my repair of a Mercury 810e mobo. It was my
first serious attempt to repair a mobo after an earlier successfull case
of a P4 mobo with swoolen caps.
_System:_ P3 1.13 GHz., Mercury 810e mobo with on board sound and video.
_Problem:_ The system would stop suddenly while working and the display
would become blank with the monitor going into standby. It could be
turned on again only by power off/on. Again the display would disappear
after some minutes and the system would require restart again. Many a
times the system would never start at all. A pci display card was tried
out but after initial bootup, it became off again and never started.
_Diagnosis:_ SMPS unit was swapped and found OK. RAM ok. On the mobo,
there is a step down circuit that converts 5V input to 1.5V output for
the bus gate circuitry. This 1.5V was missing whenever the mobo would
not start. On some occasions, luckily the mobo would start and since I
had no HDD with me, I used a live linux CD as the OS. Knoppix does not
go beyond console so 'Cool Linux', a Russian/English distro was used. It
gave a window display for a few minutes but then the system went off
again. The 1.5V fires up on power on but after a few seconds to some or
more minutes it shuts off.
_Solutions Tried:_ The dc-dc converter chip 34063 replaced but no
effect. The power caps were resoldered and the system came alive for a
few minutes, then off. The vga connector pins were resoldered and the
system ran for more than half an hour but went off. However now even
cool linux does not go beyond console. When the problems start, the
system does not start again till quite some time and a lot of fiddling.
The cpu is cool.
Any help from anyone experienced in this is most welcome. If someone can
explain the concept behind power signals, thats welcome too.
Regards,
Rony.
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