Club of the dead IBM x3550 M4

flexion

Active member
Sep 23, 2020
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Switzerland
My primary server recently died after a short power-off. Turns out this is a known problem and the IBM/Lenovo forums is full of people with dead M4's suffering the very same issue. Without firmware upgrade, one of the VT261WF voltage regulator chips can be fried on power on.

If you're an owner of such an M4 x3550 or x3650: Do not turn off your server, perform a firmware upgrade via IMM first!!!!

So my server won't start up, I already located the fried component and also ordered replacement chips.. but, jeeez, this chip is super tiny!!! just 3.5 millimeters!

any ideas how to remove and replace?

fuck-ibm.jpeg
 

flexion

Active member
Sep 23, 2020
118
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Switzerland
thanks to cz7asm for his advice to use a hot air gun and kapton tape to protect the surrounding parts. I've never done that before and I have to find the required tools for this first. Pretty sure this will end in a disaster :D
 

weblacky

Member
Jan 13, 2020
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Seattle, WA
This appears to be a QFN package. Removal won't be too hard, installation will be tougher. You can find some good YouTube content on these packages.


You need to preheat your entire board to something like 200C to start with...perhaps higher to pre-warm it. This isn't hot enough to desolder anything, but you need to warm up ALL the base metals in the PCB or they will act as a heat sink. If you find something to use a stand-offs you "could" to use a normal cooking oven and slide out the oven rack when doing the work. You don't want to thermal shock it, so you'd want to place it in and then heat the oven, not place it in a pre-heated oven. Also, cooking ovens are designed to overshoot the target temp because they expect you to open the door afterward to place food in, which immediately lowers the temps. So assume a 10-15 degree overshoot when doing this!

While you might be able to get away without preheating. If you're not practiced, you run the risk of blackening and delaminating the PCB board by directing too much heat into it with a hot air tool. If this happens, internal track damage may result. Warming the board along WITH a hot air tool at a higher temp ~ 400C or a little higher will be used to remove the chip.


What you're going to want to do is do the removal and first stage install in a single motion, then you can let the board cool the perform the REST of the install then.

Removal/Install: Place the board with some kind of metal/ceramic standoffs in the oven (nuts and bolts through the stand-off holes may work), assume over-temp so set for something like ~190C, Let it preheat, make sure you have GOOD tweezers (I mean it) and the replacement chip ready. You need to hot air tool set to something like ~400-430C. Make sure you understand the orientation ahead of time, don't get the part oriented (rotated) incorrectly. Place the board in a cool oven, set to temp, watch it heat. Make sure the air tool is turned on a ready so it will reach temp before the oven does (offset by a few minutes). When the oven reaches temp, be prepared to slide out the oven rack with the board on it facing the correct way already. Turn off the oven now.

Try to pluck the regulator off it, likely it won't come off (testing it), use the hot air tool to heat the regulator up while gently testing by pulling. It will come off very fast, have a dish or place ready to place it in. Immediately get the new regulator, apply gel flux to the UNDERSIDE of the regulator (shinny region) and place it in place on the board now (remember orientation), use the hot air tool and reheat the region again and watch that the chip floats a little into place. If the chip floats in place, try giving it a very small nudge and it moves and then RETURNS to its place...then that's IT, the hard part is done.

Let the entire board cool and go relax, it will take time to cool, give it like an hour.

Now the underside of the chip was a large center pad and small leg-like pads. The previous step should have attached the CENTER pad correctly and maybe some of the legs. You need a good iron at around 400C, apply flux gel to the perimeter of the chip, then use the iron and a small amount of additional solder is wet the iron the pass the iron through the flux against the perimeter of the chip, reflowing the "fake legs" of the chip. All those legs didn't attach correctly during the oven stunt, likely this won't cause it to unsolder, just melt the edges and let the solder reflow under into the leg-pads. Rake all four sides until the solder look good and well attach to the chip sidewall.

Then let it cool and clean the area. Now the time for testing!
 
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fraserN64

New member
Aug 20, 2019
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Kapton Tape is a great tip, wider is better!
It's hard to tell if the pins on that component are visible or entirely under the IC.
Visible you might be able to do it with a soldering iron, you will need a small tip, I actually recommend a knife edge shape.
If the pins are entirely underneath a hot air rework station will be the better tool.

My advice
  1. Don't compromise on the tools, they don't have to be over the top expensive but don't use a plumbing soldering iron on electronics.
  2. A new hot air rework station is pretty cheap now (3x the price 5+ years ago) Example: https://www.ebay.com/itm/382685375278 I have the 852A model which has served me well for occasional use.
  3. A Flux Pen and fine gauge solder will be very important as well.
  4. If you have an Electronics Recycle shop near you maybe you can buy a PC motherboard for a few dollars that you can practice removing then re-installing components.
 
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flexion

Active member
Sep 23, 2020
118
75
28
Switzerland
Thanks a lot weblacky and fraserN64 for your input! Much appreciated!
I will look to buy or lend the mentioned tools and also try to practice on some other PCBs first.
I've got a pretty small tip on my Weller soldering iron, but this chip is so small, I can barely see the pins even when wearing glasses and watching through a magnifying glass 😳 But from what I've discovered so far on the internet about this chip, it also has contact points underneath it, so it has to be done with hot air. oh my...
 

weblacky

Member
Jan 13, 2020
91
23
8
Seattle, WA
Wow, then you’ll want to try placing it on like saw horses and pointing a heat gun from the bottom (a ways away, 2ft) and wave it around to try I warm the board evenly. Friends help, it will likely take you 20 minutes to accomplish and they will need to keep waving the hot air under the entire board as you work on it. Don’t focus the hot air gun. Keep it moving, wave it, don’t get closer the 2ft as heat guns run uncontrolled and can desolder or damage the board.

A friend can lay on their back facing up and heat the bottom of the board, while you work on the top face.
 
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