Killer Instinct CPU Reflow Fail

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    • Killer Instinct CPU Reflow Fail

      Hi guys,

      I bought a broken KI board from ebay for a good price, originally intending to use it as a parts board to fix another broken KI board. I've since got that one going to the point I don't think parts will be required from this one, and when looking at it it's very clean with only a couple of missing parts that are common, non custom parts. So I would like to try and get it going again.

      Herein lies the rub - someone has attempted a reflow on this CPU (and like we've all done at some point or another) overestimated their skills and equipment and the result is a fairly big mess. I've seen worse but it's pretty bad. I'm sure that there's people who have repaired this kind of thing, and worse, and I need your help to work out the best way forward.

      Here is a picture of what all 4 sides basically look like, ignore the brown residue, it's flux I put on there to try and get the solder to flow so I could try and remove some of it. I'm not sure what kind of solder it is but it has a fairly high melting temperature and it really doesn't want to budge.



      There's basically solid solder across almost all of the pins, as well as a heap of pins bent out of alignment on all 4 sides, some worse than others, this side is the worst for solder, the side on the left is the worst for bent pins.

      I'm thinking the best option would be to completely remove the CPU, clean it up off board and realign the pins and then reinstall it. I tried using a hot air gun but again due to the solder used it doesn't seem to want to flow even with the hot air at 300C. I'm thinking the best option might be chip-quik?

      Any help would be appreciated or if someone wants to take a crack at it and has the skills to pull it off, I'm happy to leave it to someone else to get it done properly. I've reflowed a couple of these now but this is something else.
    • It's a MIPS4600 CPU so I imagine it's a standard package, probably an Altera device. Heatsink is glued on yes - looks like it's a QFP208

      I don't have an SMD station (as in those that can provide hot air and suction to remove a chip) just a cheap hot air rework station. I assume this would be fine with the right size attachment? I've used this same unit before to remove CPS1 A custom chips.

      Am I right in thinking the best option here is to completely remove it rather than try to correct it in place?
    • xodaraP wrote:

      I'm thinking the best option would be to completely remove the CPU, clean it up off board and realign the pins and then reinstall it. I tried using a hot air gun but again due to the solder used it doesn't seem to want to flow even with the hot air at 300C. I'm thinking the best option might be chip-quik?
      I agree the best course will be to remove the CPU and start fresh. From the photo you can see some legs have been pushed off their pad and shorting into another.

      Do not have experience with removing heatsink on this board, but my method that has never failed is to heat the heatsink and twist it off rather than prying upwards. Perhaps others can comment on how it is bonded for KI.

      If the solder type is unknown and not easily melting, I will apply even more solder of a known type to dilute then use wick/flux to remove. Highly recommed NOT using rosin flux. (rosin core solder is okay, but the flux makes a mess imo). If you have ChipQuick on hand, may as well use that.

      Then use hot air to remove the CPU. This will put you in better position to confirm if the pcb is damaged or not from previous owner :)

      Good luck!
    • stj wrote:

      i would probably fix the bent pins with a scalpel and air or an ILS soldering tip.
      then clean it with ipa, add lots or decent flux and drag-solder each side.

      experience of this type of scenario has left me not wanting to lift such chips incase of loose pads.
      The problem with this is the sheer amount of solder that's been added and that it doesn't want to even melt at 300C - I don't want to risk damaging pads trying to get the stuff to budge. That's why I felt removing the CPU would be the better move.
    • well if it's been done with lead-free or silver loaded solder your shit out of luck because you need to be running 330-350' to melt that stuff.
      personally i use lead-free all the time, but silver-loaded solder is a disaster.
      it lowers the melting point when you put it on, but it's hell to melt again to remove.
    • btw, if you lift the chip it will still have the bridges.
      you can clean the pcb, but getting the solder off the pins will still be a bitch.

      one thing i did in the past in a similar situation where some dick had flooded a chip with what may have been chip-quik or utectic solder,
      was i melted the solder with hot air on one side, then used the other hand to run across the pins with a vac-desoldering tool.

      i'm NOT recomending it - it was one of those situations where you have to try whatever you can think of.
    • With killer instinct it's VERY dificult to remove the CPU. The pcb is just so damn fragile. There is a reason why Chad at arcade cup only did the KI repairs for like a month or two before refusing to do them anymore.If a good reflow does not work then trying to replace the cpu is a crapshoot. Chad had mentioned that the cpu was the same as early pentiums I think though he never said specifically which.

      I tried to help revive two pcbs a few years ago but the results were not good.....
    • Mitsurugi-w wrote:

      With killer instinct it's VERY dificult to remove the CPU. The pcb is just so damn fragile. There is a reason why Chad at arcade cup only did the KI repairs for like a month or two before refusing to do them anymore.If a good reflow does not work then trying to replace the cpu is a crapshoot. Chad had mentioned that the cpu was the same as early pentiums I think though he never said specifically which.

      I tried to help revive two pcbs a few years ago but the results were not good.....
      I don't foresee any difficulty using a SMD station but I've never did it on KI myself so maybe even with the proper equipment you end up damaging the PCB...
      Looking for an OutRun board.
    • Mitsurugi-w wrote:

      With killer instinct it's VERY dificult to remove the CPU. The pcb is just so damn fragile. There is a reason why Chad at arcade cup only did the KI repairs for like a month or two before refusing to do them anymore.If a good reflow does not work then trying to replace the cpu is a crapshoot. Chad had mentioned that the cpu was the same as early pentiums I think though he never said specifically which.

      I tried to help revive two pcbs a few years ago but the results were not good.....
      This was what I was worried about.... I've reflowed a couple where the CPU had come loose but trying to remove all this excess solder is a whole other story.

      I guess at this stage though the damage has already been done so whether I can fix it or not is irrelevant, it's either possibly going to work again or it's a parts board.

      @Apocalypse I don't know if you've ever worked on a Midway Wolf Unit board (UMK3, Rampage World Tour etc) but KI is a modified version of that to give you an idea of just how fragile the boards are...
    • I have no experience with Killer Instinct boards. But if they react so poorly to heat I would use flux and a wick and try to get the solder off with that and an iron. Less chance to damage other parts.
      Then clean it and realign pins. And then solder it back in. Again probably the safest bet is good flux and an iron.

      Id avoid reflowing with hot air or infrared in this scenario.
      "No hidden button combos"
    • xodaraP wrote:

      The problem with wick is it sticks when the solder cools and you end up making a huge mess with a job like this (I've tried something similar in the past)
      i actually have kind of same problem with wick. so i used coppers from new cable instead (the one that still shines like new). and flux it a lot, i never had it sticks again. btw, with poor heat, you can always use a real 60w solder, they're really kic* ***.
    • i have never had much luck with wick for anything other than cleaning solder from the pcb connector after some asshole has soldered a jamma adapter directly to it or tried to raise the surface to counter a worn edge connector.
      that second example seems relativly common on space invaders or atari stuff.
      (a new edge connector would have been better!)
    • On my previous work, we had a tweezer sort of desoldering iron that had both legs heated. You could mount some L shaped tools that desoldered 2 sides of such a chip simultanously. First, you had to bridge all the pins with a lot of solder as you didn't wanted one to stick to it's pad when you lifted the chip. Such a tool and maybe some chip quick might be able to do the job. After that, you will need to clean the solder pads with desolder wick and remove the excess solder from the pins of the chip.
      Next is getting those straight again. Personally, I would try to find and install a new chip.