I’m not sure how many people today will remember the Asus eeePC 701, arguably, one of the earliest netbooks which drove the concept to its eventual boom. The 701 featured a stripped down specification, originally intending to be reminiscent of the one-laptop-per-child type device but utilizing Intel instead. They missed the price mark by quite a margin, and instead, it ended up being a new “toy” for developed countries instead.
I purchased my 701 for AU$415, overpaying slightly compared to the eventual $300 price point, but much cheaper than launch prices of AU$599. The device featured a 7″ screen with just 800×480 resolution, a Celeron M353 CPU underclocked at 630Mhz, and 512Mb RAM (shared with graphics). The storage was a tiny 4Gb, based around a CompactFlash controller and NAND flash, and it could run Linux or Windows XP. It had a tiny keyboard and trackpad to match, and patient users could find that it was capable of more than they would have expected.
It wasn’t perfect – it was a little on the slow side, and the battery life wasn’t spectacular, being about 3-4 hours. Charging the battery while using the netbook meant a 9-10 hour wait due to the power supply limitations, and the 4Gb SSD wasn’t fast (it stuttered) or capacious enough, so many users needed to augment it with SD card storage which was slow due to the on-board reader.
Regardless, I loved my eeePC, using it mostly for its first year, then it served three years as a dial-up modem server for the home, followed by a two year stint as a webcam server, and then finally helping me along with my PhD as a terminal to be used with a home-brew Arduino-based device.
Unfortunately, returning to my lab the other day, I discovered the laptop to be completely dead. No sign of life. Taking it home, and probing the power supply with a multimeter confirmed that the cause was a dead power supply.
Teardown and Post-Mortem
The eeePC 701 power supply is a relatively compact brick. The unit puts out 9.5v at 2.315A, with a positive centre tip, although later units seem to up the amperage slightly to 2.5A. The model number is AD59230, and it is manufactured by Pi Electronics of Hong Kong/China.
The power supply comes with a two parallel blade fold-out configuration, which is localized to the Australian plug by a clip-on adapter. Fearing that there was a contact issue, I tried the power supply without the adapter but it was still not functional. It was likely something had failed somewhere inside.
Opening the power adapter was rather difficult due to a single Torx screw, embedded at the end of a thin screw-hole where none of my screwdrivers would fit. I decided to go ahead and pry at it until it broke, seeing it as a write-off. The first PCB is on the back-side, and has a date code of Week 45 of 2007, making it almost 8 years old. The fuse, full-wave rectifier, filtering inductor, and soft-start thermistor can be seen on this side. The casing itself already shows sign of issues – notice the slight liquid residue. This residue smelt a bit like methylated spirits.
As it turns out, the primary 1A fuse had blown, with some very nice melting, to render the supply safe. Externally, there was no sign of distress, which means that the design worked as intended.
The rectified DC passes to the other side where the rest of the SMPS is placed. A close look shows two main primary-voltage caps which have bulged, one (top right) more than the other.
Extracting the board from the casing proved to be difficult and ultimately destructive due to the use of adhesive to glue the board to the case.
The same liquid residue can be seen in the back of the casing.
The whole board ended up snapping along the primary-to-secondary isolation line. There is some mild sign of heat stress and electrolyte leakage from the bottom of the capacitor. There is a spark gap at the top right, which seems interesting.
The offending primary caps are both Ltec branded, a known bad cap brand. The design squeezes a vertical PCB in for thermal monitoring and shutdown, to save space.
The bulging is more obvious from this view. The capacitors on the secondary, which are Taicon, were both perfectly fine though.
As it turns out, this is another case of bad caps claiming another victim. If the board were extracted without breaking the PCB, it might be possible to re-cap and re-use the power supply and revive it.
As a person that doesn’t give up that easily, I’ve ended up reviving the eeePC 701 by using a power supply from the “upgraded” eeePC 701SD which I was given by a friend. This keeps my existing netbook going, whereas I salvaged the cable from this power supply to hook up to a lab benchtop supply to keep the eeePC 701SD going if I’m desperate enough.