Board do not start - burned voltage regulator?

[Behemot]

I was recapping some Chaintech Apogee board but probably due to some bad soldering near memory regulators something burned as soon as I turned it on. I identified it was probably coming from an rt9173 chip which is voltage regulator. I measured the VOUT pin and it reads 0,7 V only - too low for memory. The boards beeps as it detects no memory - so I guess it really is this chip?

[Pyr0Beast]

Re: Board do not start - burned voltage regulator?

Replace mosfet

[Behemot]

Re: Board do not start - burned voltage regulator?

I of course measured them, but they did not seem shorted. Also the board was more heated around the regulator than mosfets.

[Pyr0Beast]

Re: Board do not start - burned voltage regulator?

mosfets may also fail open

Well. It might be the regulator's fault after all.

[cmosbios]

Re: Board do not start - burned voltage regulator?

like they always say, do not try to fix when it is not broken. try different working RAM first that the board supports ...

[PCBONEZ]

Re: Board do not start - burned voltage regulator?

Why do you think RT9173 is for RAM power?
Did you trace the circuit?
There are other RAM related voltages that are less than the power voltage.
I'm just saying check to see what it powers.............

[cmosbios]

Re: Board do not start - burned voltage regulator?

what is it look like? i mean the regulator you are saying. isnt it that Mosfets are also regulators?

[PCBONEZ]

Re: Board do not start - burned voltage regulator?

MOSFETs regulate by switching.
The switching is controlled by an IC chip [or chips.].
Those IC chips have regulators to control their voltages that are not MOSFETs.

THOSE regulators can be just a transistor or yet another IC chip.
One popular type [on mobos] is called an LDO regualtor. {Low Drop Out}

If the power regulator to the IC chip that controls the MOSFET is screwed up then so can be the output of the MOSFET.

LDOs are also used to power IC chips that have nothing to do with MOSFETs.
There is usually at least one regulating any IC chip and there's usually a cluster of them around the chipset.

Does your head hurt yet?
.

http://www.google.com/#sclient=psy&h...bb86640ae08969

.

[Behemot]

Re: Board do not start - burned voltage regulator?

I did not trace it precisely, but it's closest to RAM and also as I said, the RAM's are getting much lower votlage than they should (I meassured actually) so they are not able to start and board thinks there are no modules at all.

[Behemot]

Re: Board do not start - burned voltage regulator?

Changed the regulator, ther was indeed also one MOSFET burned. Changed it for some from the dead ASUS board I asked about in next thread - it had the same or superior values and same RdsON (14 mΩ). Now the boards runs, just memory shows indefinite amount of errors in Memtest86+. Will try to solder it better and also newrer version of the program.

[Behemot]

Re: Board do not start - burned voltage regulator?

The original MOSFET was IRL3175S, I used one 9918H.

It looks loke the regulator heats up more than what I consider to be cool, but I can still keep my finger on so it's not so bad.

[Behemot]

Re: Board do not start - burned voltage regulator?

Resoldered all legs once again. Also tried to measure voltage on small ceramics on memory module, it shows some 2,64 V which is fine for DDR. Memtest86+ v4.10 now running, so lets hope

ADD// no error so far, first pass almost done.