Asus P5N-T Deluxe : Help testing & understanding vrm.

[Gabriel]

Ok, got this mb - it does power up but does not post.

I thought this was the perfect time for me to measure and understanding the vrm circuit.
I did read the guide for vrm testing written by AK0R but did not understand everything.

There are two rows of voltage regulators, the inner row is 5525L and the outer row is 9025L.

Here are my voltages with mb on, I used gnd in the p8 plug on all of these.

Outer row towards back of mb.
Drain - 12.01V (mounting base)
Source - 1.27 V (pin 1,2 and 3)
Gate - 2.31 V

Inner row towards back of mb.
Drain - 1.27V (mounting base)
Source - 0V (pin 1,2 and 3)
Gate - 10.47V

Outer row top of mb
Drain - 12.01V (mounting base)
Source - 1.26 V (pin 1,2 and 3)
Gate - fluctuate between 1.289 to 1.296V

Inner row top of mb
Drain - 1.26 V (mounting base)
Source - 0V (pin 1,2 and 3)
Gate - fluctuate between 0.255 to 0.231V


Does this seem right or should I be worried ?

[Th3_uN1Qu3]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

You aren't going to get any useful readings from the gate unless you have an oscilloscope or a meter with frequency reading. Also when you read the gate you always read between gate and source, not between gate and ground, because what you have there is a synchronous buck converter where the high side MOSFET is some volts above ground.

Measure voltage at the CPU caps. If you get 1.something volts then Vcore is okay. If Vcore is okay, it's most likely failed BIOS.

[seanc]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Or if it's gone the same as a P5N-E SLI I had - could be a failed northbridge.

[Gabriel]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Ahh did not know the right steps for measuring gate, I updated my measurements.

Outer row towards back of mb.
Drain - 12.01V (mounting base)
Source - 1.27 V (pin 1,2 and 3)
Gate - 1.041 V

Inner row towards back of mb.
Drain - 1.27V (mounting base)
Source - 0V (pin 1,2 and 3)
Gate - 10.47V

Outer row top of mb
Drain - 12.01V (mounting base)
Source - 1.26 V (pin 1,2 and 3)
Gate - fluctuate between 0.023 - 0.030

Inner row top of mb
Drain - 1.26 V (mounting base)
Source - 0V (pin 1,2 and 3)
Gate - fluctuate between 0.255 to 0.31

I have 1.265 over the cpu caps.


Bios is ok, I know for sure.

[Gabriel]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Took the heatpipes off, tried to press down on the nb,sb and the 200 chip incase of bad bga.

Hope the main chips is ok.

[Th3_uN1Qu3]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

1.265v means the CPU VRM is likely operating in spec. How can you be sure it's not a bad BIOS chip. They can go bad by themselves.

[Gabriel]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Bios chip both reads,programs and verifies ok, I also tried to program another chip - still no post.

[Th3_uN1Qu3]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Then check the other power supplies for the northbridge and southbridge. There should be one 3.3v and one that depends on the chipset, 1.something volts.

[seanc]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Take the heatsink off and look at the northbridge chip & heatsink. There were visible scorch marks on mine.

[Gabriel]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

No scorch marks on heatsinks or chips, northbridge,southbrige and cpu get warm so they get power.

[Scenic]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

reflow northbridge.
nvidia chipset (nForce 780i SLI). dead giveaway there are gonna be problems with it..

[brethin]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Try a post card and see where its hanging on boot, guessing at shit will get you nothing and jumping right into the board with a scope or meter is pointless if you don't know where the problem lies.

[Gabriel]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Are these post cards any good ? have you tried them ?

I see lots of them on ebay, are there a type that works better then others ?

[PCBONEZ]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

It's not a complicated thing for them to build.
Most of them [even the more expensive ones] are the same Chinese junk builds,, ,, but most of them do at least work.

The difference between a good or bad one is the documentation you get with it.
The code it comes up with needs to be de-coded to mean anything and it's not the same codes for all mobos.
One that comes with most of the codes in the documentation will save you some time searching codes on the web.
Unfortunately few come with complete de-coder tables.

Also there are now 2-digit and 4-digit codes.
Since you don't know which you will need for any given mobo it's best to get one that displays both 2 and 4 digit codes.
Some do that with a switch and others simply have two read-outs.

The ones that talk about USB in the ad usually only get POWER through USB.
It needs to be connected by the interface it has plus USB to work.
Kinda dumb because any interface you would connect it to has power pins available already.
.

[Scenic]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

i've bought a chinese cheapo card (under 10eur incl. shipping) from ebay seller virtualvillage ages ago. my card seems to be model number LP50A1

does what it's supposed to but not more. has a PCI connector and a parallel port connector.
the USB port on that card is just for 5V power if you're using the parallel port (on laptops for example). if you're using it in a PCI slot you won't need it.
has a little piezo noisemaker on it that you can connect to the board's speaker pins if it doesn't have one and a row of LEDs for -12V, +12V, +5V, IRDY, CLK, +3.3V, RESET, FRAME.

manual is (of couse) in finest engrish, but it at least lists all the possible codes and explains the "menu" of that card (self-test, scrolling through previous POST codes, 2 or 4 digit operation, beep codes etc. ...)

helped me out countless times on seemingly dead boards so far..

http://bambooz.pytalhost.net/badcaps/post1.jpg
http://bambooz.pytalhost.net/badcaps/post2.jpg

suprisingly, they still exist about 2 or 3 years after i bought this card. their website is slow as hell & pretty cheesy though.
http://www.61131568.com

[Uranium-235]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

wow, 2003-2023! this cards from the future guyz!

[PCBONEZ]

Re: Asus P5N-T Deluxe : Help testing & understanding vrm.

Actually the © for most corporate works is 95 years so 2003-2098 would be more correct.
.