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ASUS P5A Issues

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First post, by Smack2k

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Trying to test my P5A board and having issues where once the PSU (I've tried 3) is plugged in and the PSU switched on, the board power comes on, the CPU fan spins (not at full speed it seems), the PSU Fan spins (not at full speed seems), the lights on my PS/2 Keyboard start blinking over and over. ITs almost like the board is in a constant reset.

I've removed everything but the video card and same issue. Tried PCI and AGP known good video cards... Tried Several RAM configs and different PC100 sticks. I've checked the jumpers for the K6-2 400 I have in there and they are correct. Same issue happened with a P233 MMX I tested with, with those jumpers correct asa well. Reset CMOS, removed teh CMOS battery entirely and same thing each time.

WIth case wires plugged to board (Power Switch, Reset, etc) it makes no difference. As soon as I switch the PSU on, the board tries to boot and the issues above start, blinking keyboard lights and the fans getting some speed but not full and I swear it looks like the fans start and begin to stop but quickly start again and so on (its so fast you have to stare at it to notice the small change in speed). Its like something is causing it to reset. You can hear the CPU fan stop and start repeatedly listening closely to it

Its been taken out of the case and put on test bench and then just on cardboard as well...

Any ideas?

EDIT - I find that if I short the reset pins on the board with a screw driver and hold it there the CPU fans stop and the board seems like it would with PSU on but power not switched on, but as soon as I remove the screw driver, it starts back on its process....

Reply 1 of 9, by Horun

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So you breadboarded it. Good ! Sounds like the board is getting a Power On Signal when it should not. I suggest you remove everything (cpu, ram, etc) and use a DVM and check resistance of the psu connector from all the main input volts to ground. If any are less than about 500 ohms then there is a short or caps have gone bad. Most should read in the near meg-ohm range except the +5v (assuming it is what the CPU VRM is using) which should read about 800-2000ohm or more. If you need a pin out of the ATX connector look here: https://i1.wp.com/powersupply33.com/wp-conten … pply-Pinout.jpg

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 2 of 9, by pentiumspeed

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Make sure the cmos battery is good otherwise replace it. CR2032

Cheers,

Great Northern aka Canada.

Reply 3 of 9, by Smack2k

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Horun wrote on 2020-03-16, 01:43:

So you breadboarded it. Good ! Sounds like the board is getting a Power On Signal when it should not. I suggest you remove everything (cpu, ram, etc) and use a DVM and check resistance of the psu connector from all the main input volts to ground. If any are less than about 500 ohms then there is a short or caps have gone bad. Most should read in the near meg-ohm range except the +5v (assuming it is what the CPU VRM is using) which should read about 800-2000ohm or more. If you need a pin out of the ATX connector look here: https://i1.wp.com/powersupply33.com/wp-conten … pply-Pinout.jpg

Thanks, I will give this a shot....

I changed out the CMOS battery, didnt help there either.....

Reply 4 of 9, by Smack2k

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If I have the board out of the case, what is good to use for ground so I can test the resistance of the motherboard connector?

Reply 5 of 9, by Horun

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Smack2k wrote on 2020-03-16, 21:39:

If I have the board out of the case, what is good to use for ground so I can test the resistance of the motherboard connector?

I use board mount holes with the solder rings as Ground all the time for testing, or you could use one of the Grounds in the ATX connector. Either one....

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 6 of 9, by Smack2k

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OK,

Looks like I have an issue....I grounded one probe to metal on parallel connectors (its clean and bare metal) and tested Pins 3, 5, 7, 13, 15, 16, 17 (ground Pins per article I found). Zero'd out the meter first and had it on 200 ohm. Meter had a solid 1 after zeroing them out and pulling the probes apart. Not an electrical guy as you can probably see, so learning as I go

3 - Stayed at 1 on the meter
5 - jumped all over the place into 100's
7 - 0
13 - Stayed at 1 on the meter
15 - Jumped to 4-6 ohms
16 - same as 15
17 - 0

So maybe I did it wrong or there is an issue with the connector....

Reply 7 of 9, by Horun

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Uhh if you look at my image link you should note (assuming what your pinout is same as that).. Pins 3, 5, 7, 13, 15, 16 and 17 are all ground. It is the +3.3, +5, +12 and -12 that are important.

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 9 of 9, by Smack2k

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What is proper process to test the motherboard CPU connector with a multimeter? Want to make sure I do it right.

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