Need help on PCI board.

[heibear]

Hello folks, I recently designed a 3.3V 33Mhz PCI I/O board without PnP support. This is actually my first experience with PCI interface so I was expecting troubles. The current trouble is that once I install the card into the slot, the computer cannot be turned on, or the power supply simply locks itself down. I am pluging the card into a 5V-PCI slot using Universal keyslot.
I suspect that there was a voltage mismatch so the motherboard didn't pass the startup test. Does anyone have any idea on what's the problem? And how to solve it?
Thanks!!!

Heibear

 

[felixc]

Well, if your 3.3V card can not undertake 5-volt signals, it means that the 5-volt signals on the PCI bus are getting shorted to the 3.3V rail when they are driving a high. This may overdrive the PCI interface chips.

But if the power supply does not even start, then it may be something more serious. Like a short on power supply lines. Verify that something stupid hasn't been done, like mistaking side A and B.

 

[MikeHalloran]

On a PC, the power supply won't start unless its RST\ input is allowed to go high.

Check pin position 15, side B on your board.





Mike Halloran
Pembroke Pines, FL, USA