I recently got Wifi Pineapple Mark V from eBay, for about 15€ or so. Although the Mark V has since been superseded by a superior model, that is still a very good price. The main reason for this is, that it has a defective power connector and can now only be powered by USB. Since that didn’t sound like a big deal to me, I decided to give it a try. I figured, that it can’t be that hard to fix and even if I couldn’t, I could Hotwire 5V to the USB port somehow.
At first I thought it might be a damaged connector or a PCB trace that had burnt through. But a first glance I couldn’t see anything wrong. So I just plugged it into a weird adapter cable and played a few days with my new, slightly broken, Wifi Pineapple V. As far as I could tell, everything worked perfectly, so at least I got a working Pineapple out of it.
After I was done with testing/playing, I decided it was time to figure out, what was actually wrong with it. Again, nothing looked damaged but now that I was paying closer attention, I realized, that I can’t seem to find the voltage regulators. After following the PCB traces more carefully, it turns out, that the power bus part of the Pineapple Mark V is actually on the other side of the PCB. It is hidden under a metal shield, so I originally thought, that it housed part of the RF circuit or something. Turns out, there are a bunch of SMPS hidden under the shield and will you look at that: I found the defect.
It is a little bit hard to see, but the chip is a Fitipower FR9888, Step-Down Converter. Weirdly enough, the damage looks like rapid overheating, although the chip can tolerate up to 23V, while supplying 2.3A. It also has short circuit and thermal protection. So I can’t even guess, what the previous owner attempted to do in order to fry that poor little Step-Down Converter. I also have neither heard of that chip nor of that company before but the available Datasheet looks pretty promising. Especially the PCB layout recommendation looks like the figurative grandfather of the circuitry on the Mark V PCB. Lucks seems to be on my side, since I have not only identified the Problem, but was also able to find the chip on ebay, for about 3€. For 5 pieces. That is the smallest quantity I could find. Guess the FR9888’s most important function in this circuit is cost reduction. But, hey, whatever works. I don’t judge.
I used my rework station to exchange the chip, which was more difficult than I thought, because Pin number 2 was literally welded to the PCB trace. Not entirely surprising, since this is the Pin where the external power supply is connected to. I still have no idea what the previous owner was messing around with, guess we will never know.
But hey, I have a fully functional Pineapple!