Asus P4B266-C won't POST and makes noise

[lucky13]

I am not having too much success lately with recaps....

This board won't POST.

Actually, when you press the power button, first the P/S (pretty sure where the noise was from), makes a few short ticking noise (like keyboard held down).

Then the single beep from the speaker but no video...and then the ticking noise continues. I even pulled out the keyboard and mouse but the noise continues.

I looked at the major caps and they are:

Taicon 1200uF/16V (3 pcs)
Taicon 3300uF/6.3V (6 pcs)

I checked this forum and see that I need to replace them.

So I replaced them with Rubycon MBZ 1500uF/16V and 3300uF/6.3V MBZ.

(Note: These Taicon caps were then brought to work using the ESR meter (analog type) and they are less than 0.1ohm (hard to tell, depends how hard I push the test probe on the cap legs). So I think the caps were not the problem.)

When I start up again, it took longer (maybe 2-4 sec) before the ticking noise starts again. Still no POST. I haven't touch this board in over a week as I turned my attention to the Gigabyte board.

Then I see that this mobo perhaps uses a 2phase VRM too like the Gigabyte.



So I ohm the MOSFET again between Drain and Source and again I find it to be very low ohms.

With CPU in, I get 11.3ohm (this is better than the Gigabyte where I get 0.2ohm)

With CPU out, I get 63 ohms.

I use magnifier and checked for shorts on where I had soldered but found none.

I think both my problems are related?

[lucky13]

Reference Gigabyte GA-8IR533

OK, now that I am looking for 2phase VRMs as reference....

I have this GA-8IR533 that had been recapped and I use it for testing hardware.



This board works; absolutely no problem (after I got rid of all the Choyo).

Again, following the example of testing the other 2 boards that have problem POSTing, I measure the red circled MOSFET and found:

with CPU 4.6ohms
w/o CPU 72 ohms

Give me another 10 ohms and I think this Asus board will work?