Resurrection weekend...

[skiddz]

Put new floors in my house and when I was putting my office back together, I found a few old motherboards I'd left for dead.. All Abits.. A couple BF6s and a well seasoned BX6-2.. For giggles, I thought I'd try and resurrect them with my trusty soldering iron and some new Nichicon caps... Called my Mouser rep, gave him some part numbers from page 572 of the latest catalog and a couple days later, I've got a box of caps.

1st BF6 took a couple hours to do, but it posted on the 1st try and I was able to stuff in an old Celeron 566 on an MSI Slotket adapter and OC it to 850MHz.. 24 hours with Prime95 showed no problems at all.

2nd BF6 took less than an hour (I had my methods worked out after 22 caps on the 1st one) and resulted in another saved board. This one got a PIII/1000 on a slotket adapter and it's chugging along on Prime 95 at 1.33GHz. No problems.

The BX6-2 is still in surgery, but I'm hopeful it'll be back up and working in an hour or so. I just had to take a moment to offer my thanks to badcaps.com for the info I needed to make this happen. (and to get away from the magnifying glass - my eyes are tired!)

[Chris1992]

Re: Resurrection weekend...

Nice to hear success stories. Pics would also be nice.

[skiddz]

Re: Resurrection weekend...

Alas, the BX6-2 seems to be dead.. Replaced the usual suspects and no joy. No beeps, no nothing.. Individual components are all ok as they work in the BF6s.. Don't see any damage to the board and it's failure wasn't dramatic. Just wouldn't POST one day - same as after surgery.. No beeps or anything.

Should have taken pics while the boards were on the bech, but I've got 'em all built up - one's in my rack in my office and the other is in my daughter's room..

I'm kinda bummed about the BX6 tho. I've had that board running since the C300a@450 days and this is it's 3rd or 4th iteration with a C566@850 (Same as the BP6 I saved)

Might have another one to work on.. The Dell Dimension that's my house's Win2k server started "singing" last night and locked up a couple times today.. (Thankfully my backup domain controller is still solid..) If/When I do that one, I'll take some pics..

[AK0R]

Re: Resurrection weekend...

Check for a shorted or open VRM. Any one of them bad could prevent the board from POSTing.

[skiddz]

Re: Resurrection weekend...

Pardon my ignorance, but I just walked in from another 13 hour day and my brain is fried... What's a VRM and what do they look like? Voltage regulator? I know what those are... That'd be nice if that's what it is..

Thx!

[Calchaqui]

Re: Resurrection weekend...

I think AK0R is meaning mosfets and the VRM chip which switching them .
I've seen mosfets toasted and good VRM, but if VRM is toasted or shorted, than, mobo is dead.

[Rainbow]

Re: Resurrection weekend...

The VRM chips can be replaced too - but you have to find exact same type. Boards with bad VRM chips wait until I get another board which can't be repaired (fried chipset) but the VRM chip is still good. The problem is that there are many different types of VRM chips - but I've already repaired some boards.

[skiddz]

Re: Resurrection weekend...

OK, I guess the VRM isn't what I thought it was.. Can someone post or send me a pic with that I should be looking for (and how to check for shorts/opens??)

This has become sort of a personal challenge now..

[Rainbow]

Re: Resurrection weekend...

VRM is composed of:
1. VRM controller - a small chip with 16 or more pins
1.5 MOFSET drivers - small 8-pin chips if not integrated into VRM controller
2. MOSFETs - the black things with two pins and back soldered to the board
3. coils
4. capacitors

If the caps go bad, the MOSFETs can short - and that can damage the MOSFET drivers or VRM controller.

[Calchaqui]

Re: Resurrection weekend...

Perfect Explanation Rainbow . Yes, but how to desolder a VRM chip, it is solder on the surface of the PCB, I've tried with a "pencil" 15W Soldering Iron, 3 hours , and nothing , i couldnt. Also even different models of VRM has the same Pin out, and they works.

[skiddz]

Re: Resurrection weekend...

OK, armed with that bit of knowledge, again, how does one check VRMs or Mosfets for shorts/opens??

[Calchaqui]

Re: Resurrection weekend...

Here is the link: https://www.badcaps.net/forum/showth...&highlight=VRM
I dont understand quite well because of my enligsh and specific vocabulary. I'd love a FAQ with a mini-DICTONARY . I mean, what means VRM IC, is that the buck controller a.k.a VRM chip . Generally, what means IC ?

Sorry for the questions.

[Chris1992]

Re: Resurrection weekend...

IC is integrated circuit, which is a chip. Yo se bastante espanol de hablarle en espanol, si eso ayude. (no puedo hacer acentos en este teclado)

[Calchaqui]

Re: Resurrection weekend...

Perfect Chris1992, I think the right thing is that i must learn english well :P .
By the way, almost all short/dead mosfets I've seen also they took away the VRM IC.., is that a rule?. Change mosfets is hard but possiblechange IC a lottaaa harder

[Rainbow]

Re: Resurrection weekend...

If there's no resistor between the MOSFET driver and MOSFET's base, then the driver (which is sometimes integrated in the VRM controller) is likely to be damaged by shorted MOSFET. The reverse can also happen - bad VRM controller can open both upper and lower MOSFET, effectively shorting 5V (or 12V) to ground through them - but haven't seen that yet.

[Calchaqui]

Re: Resurrection weekend...

Rainbow, thank you for answer. How could I know if the Driver mosfets is integrated in the VRM chip, I mean, in example for the IC HIP6019BCB . I read the datasheet, and doesnt talk about driver mosfets, but i dont see another chip next to mosfets and IC in the mobo .

datasheet: (almost the same)

[Calchaqui]

Re: Resurrection weekend...

Sorry, again, given this pics, how is possible to know if the mobo has driver mosfets chip (not integrated in the IC), and if there is some resistor btw mosfets and IC

http://www.soyogroup.com/images/prod...0x600/6vca.jpg
http://www.xbitlabs.com/images/mainb...3v4x/p3v4x.jpg
http://www.soyogroup.com/images/prod...00/7vba133.jpg

Thanks a lotta in advance

[Rainbow]

Re: Resurrection weekend...

In the datasheet, see the chip pinout - if it has UGATE and LGATE outputs (or something like that), that means that it can directly drive the MOSFETs.
Also see "typical application" in datasheet - that shows if the MOSFETs are connected directly to the chip or to the driver chips (see e.g. HIP6302 datasheet, it's used with HIP6601 drivers). P2/P3 board typically use all-in-one chips but many Socket A boards use external drivers.

[skiddz]

Re: Resurrection weekend...

OK, did some more poking and prodding with my meter and found what I believe to be a bad VRM. Unfortunately I can't make out any nomenclature on the thing so have no clue what part I might be able to replace it with... Oh well, 2/3 is still a 67% success rate.. The "saved" machines are rock-solid with over 72 hours of Prime 95 time on each of them.

$35 in caps, a few hours of my time and a couple Newcastle Brown Ales made it all worthwhile.

[AK0R]

Re: Resurrection weekend...

OK, did some more poking and prodding with my meter and found what I believe to be a bad VRM. Unfortunately I can't make out any nomenclature on the thing so have no clue what part I might be able to replace it with.

What is the component number? Chances are good that someone on this board can tell you what should go there.