MCUmall EPROM BIOS Chip Burner Forum
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 12V ... strange problem

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TailS_tff Posted - 05/09/2004 : 08:25:29
Hi !!

I would like to know if the 12V entry is filtered ?
(I apply 20V dc ... is it bad ??)
I noticed the 4 diodes and the condensator for filter the 12V entry but is there zener diode after ?

I flash one bios using the willem based programer and the computer seems to have some boot problem :

from a cold boot, the computer start normally :
agp init ok
mem test ok
drive init ok
but an second "beep" occured

windows start normally ... but if I press reset for example, the computer refuse to reboot .. it seem the bios start process is loop
(drive like cd unit continualy init all 4 or 5 second) and the screen
still black.
same thing if I stop the computer normally and I try to switch it on...

Is a bad power supply can destroy some part of bios chip ?

Thank for helping me ^^

TailS - the french fox
5   L A T E S T    R E P L I E S    (Newest First)
tulufan Posted - 05/11/2004 : 08:24:11
You are welcome.
Good to hear you can press reset successfully before the second beep.

This means your BIOS chip is not damaged.

Now, if you confirmed your BIOS software is no problem, (e.g. Revision)
Then you may need a POST Diagnostic card to determine where the CUP stopped the boot sequence.

Good luck.
TailS_tff Posted - 05/11/2004 : 01:13:28
Hi ^^

I already test the motherboard without any peripheral.
In fact, before the second beep, I can press reset and all it running fine (boot process)... but just after the second beep, a reset event just block the computer.

Thanks Tulufan for your replies !

TailS - the french fox
tulufan Posted - 05/10/2004 : 10:58:36
20V dc to the 12V entry should be OK. There is a 5V regulator after that AC/DC entry. It's better to use the lower AC/DC power (9V - 12V), other wise the 5V regulator(7805) will be very hot.

I believe the BIOS chip is in a good shape,since it can be read/write/verify correctly by programmer. The whole bios chip is only for store the boot up program only, the CPU of your mother board will read it during the booting time. If the programmer read it OK, the CPU should read it OK.

If possiable, remove all other device cards in the mother board slot, just keep the minimume mother board hadware config for testing.

Press "reset" fore second "Beep". If this works, that means some hardware problem.
TailS_tff Posted - 05/10/2004 : 00:22:57
Hi !

Yep, the programer is the willem programer.
I apply 20V dc to the 12V entry.
the chip is W49F002U (winbond)

Thank !

TailS - the french fox
tulufan Posted - 05/09/2004 : 21:50:23
I do not think the bad voltage will only partially demage the bios chip.

But I do not know which 12V you are reffering to. Willem programmer? Where did you apply the 20V dc to ?

It looks like some where else got wrong to me. Not hte bios chip.

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