I bought this Network Attached Storage (NAS) back in 2012 to host all my work related VMs, pictures, and computer games. Initially I wanted to fill up all five bays with 2 Tb drives but the cost would've been prohibitive. Thus I bought only two Western Digital Red 2 Tb drives with the thought of adding more as I run out of space. Funnily enough, I am still running with those two 2 Tb drives in RAID-1 configuration. And I still have about 300 Gb free space. This is filling up quickly these days since both my digital still camera and the mobile phone take pictures with an average size of 6 Mb.
Recently while I was investigating the possibility of switching the magnetic drives with Western Digital Red 2 Tb SSDs, I found some alarming pictures of the NAS mainboard. People were complaining about capacitor plague. I thought this was an issue of the early 2000s but apparently the early 2010s were also affected. I saw pictures of bulged or leaked electrolytic capacitors.
Frightened enough, I opened my NAS and found out that disaster already happened.
There is one supercapacitor rated 1 F / 2.5 V which has leaked electrolyte all over. It completely corroded one of its own legs and some exposed copper. The capacitor top side solder pads are completely eaten away. Thankfully the bottom solder side is what carries the power tracks. Thus no problems whatsoever. I can install a new part instead. I believe this capacitor is used for time keeping. But the NAS worked perfectly without it because I have enabled NTP time synchronization.
I cleaned the area as much as I could with acetone, 300 degrees heated flux (weird method, but it works) and mechanical scraping. There is also a quartz crystal in a SMD package which presents some corrosion on the shielding bare copper section behind it. I am thinking of actually completely replacing this by a standard radial package so that I can clean the underneaths. The package is marked EAMC. The first letter is identifier for the Epson company. The second letter indicates that this is a 32.768 kHz fundamental frequency crystal. The last two letters are actually production date code.
I have used a quality AVX supercapacitor rated 1 F / 2.7 V, in place of the faulty one (branded Nano Force -- say what?). As for the rest of the capacitors, I went with single-ended conductive polymer aluminum solid capacitors made by Kemet. At least these don't leak any electrolyte when their lifespan ends.
The dreaded SAMXON electrolytic capacitors. There should be a place in hell for these junk parts. I would be happily paying $ 10 - $ 20 more for the same product with capacitors coming from a reputable manufacturer. Planned obsolescence? Cost cuttings? Choose your poison.
I can see that the three bulged capacitors belong to the power supply section. These are over-stressed. The other SAMXON capacitors that are used for SATA drive power supply ripple filter circuits are not bulged, yet.
Being aware that corrosion could eat under the soldermask, possibly extending to vital circuit tracks, I decided to replace the quartz crystal. This allows me to clean the copper under the SMD package. I chose to replace it with a standard radial package quartz oscillator of the same frequency rating, because it's easier for me to solder it in place.
That's what the mainboard looks like after the repair.
With the NAS mainboard fixed, I can begin re-thinking about drive replacements. Those two magnetic drives have 8 years of 24/7 operation. Although they still work, they can be considered end-of-life products.
PS: As a side note, I am astounded that they used a 120 mm Noctua fan. I was living under the impression that Noctua is something of a more recent date. Then again, seeing a premium fan in a mass production device is kind of a great surprise. It even still works great without producing any weird noises.
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