Monday, March 11, 2013

Laptop Hacking and Hardware Workarounds

If you've been around long enough sometimes you'll realise that people are sometimes unwilling to pay for the parts required in order to get the job done and you have to make do. A while back someone left me with an Acer Aspire One which had its fair share of problems but I was able to get going.

However, he neglected to purchase a power switch/cable. Obviously, these are key parts of any electronic device but the cost of them actually constitute a large proportion of the cost of the device itself. I've decided to turn it into an experimental device.

By hooking pins 2/3 of the power connector on mainboard to the the pins corresponding to relevant contact points of a 3.5mm sound socket/plug (a multi-meter with an audible continuity tester is extremely useful but you can also use guesswork, or a battery, some wires, and a standard multi-meter/LED to get around this problem) I've turned the the microphone socket into a a partial solution to power control. The other part involes a microphone plug which is then hooked up to a SPST LED switch.

While I was in Jaycar I noticed these (SPST switches that require a physical key). Not a bad security option actually... How can you hack something if you can't  power it up?

- clear that this particular machine had poor build quality. Even some basic things like the SD card reader slot needed some more thought/work. Based on personal experience tolerances and physical dimensions of memory cards are not identical and often vary from one manufacturer to another which means that sometimes cards from a particular manufacturer will get stuck and need to be extracted via abnormal means. This card slot erred on the side of being slightly too small. So many extra pieces which were not required. Small number of larger panels compared to larger number of smaller panels more preferable as the smaller ones tend to break more easily. Better to use more screws than snap lock type systems which when breached are often unrealistic to repair in spite of advances in glues, cements, and my experiments with plastic welding.

- if you've ever repaired/modified laptops before you'll realise how specialised how some parts are and how difficult it is to find replacements (which are often expensive as well). This is particularly the case with parallel style cables that are often used for data transfer. I fashioned the required cable by using Scotch tape and filaments extracted from multi-stranded wire from junk electronic equipment. Obviously, this is not easy and could lead to terminal problems. I consider it only a method of last resort because if you don't do the job cleanly it's likely you'll have reached a point of no return and won't be able to go back. Some tips,  remove the clamps which hold the cables in place, clean the connections first, and then attempt to add some solder/flux to the relevant elements which you mean to connect. Then attempt to the final connection. Obviously, too high a level of heat and you could burn away tracks, to low and you won't be able to get the solder to flow and it will increase the difficulty of the job. Not enough solder will mean a loose connection while too much will make it hard to put the system back together without deformities.

- fashioning a cable is not easy. Try to make life easier for yourself. Use maintenance manuals when/where ever possible to find out which connections are superfluous and do not bother with them.

The reason why I say this is because making a cable is far more difficult than you think without a decent lab/equipment (use cables from another laptop if at all possible!). Simple things like keeping the wiring straight and insulated from it's neighbour are an issue. Several options include:

- using a single wire strand and then enclosing it with tape, then wrapping this with the next wire and so on
- using paper to create a backing which you could then begin to glue the wires to
Reaslitically you're limited to creating cables only for:
- speakers
- memory cards
- trackpads
- power
- antennas
Basically anything less than six pins/connections and it shouldn't be too difficult. Any more and you'll require skill/patience/time.

Data card (optical drive and hard drive in particular) cables should definitely not be attempted by those who don't have good hands and technical knowledge. As I've discovered many odd things that can result which with cause/effects relationships that are not immediately clear when making custom modifications. In my case, the Aspire One works perfectly fine if you leave the switch in permanently. Remove it and re-insert (or any other electronic devices such as USB devices) while the power source remains intact and the machine may not boot properly next time (fiddle around with the ordering and it will work again though. Need more time to understand the bug compeltely...).  Like I've said though it's a hack and does minimal/no permanent damage to the system (I was considering drilling but there's little room to work with as it is. The recording socket seemed like the most obvious option since it is rarely used unlike network and USB ports).

- use dollar/discount store as a place from which to extract parts from toys which you can not find elsewhere. Membrane type switches are a constant source of pain for me and often I find that just breaking it off from another device is the only way that I can find one (creating one is also possible but also requires skill/time/patience. Possibly more than that required of creating a cable)

BIOS hacking introduction/roundup for those who are interested (a continuation from some of my previous posts/work obviously. Even if it is related to compliance issues there are surely better ways around this than a hardware whitelist?).

Freezing issue on an Acer. Interesting how many tangets they took.

Linux on the Toshiba AC100. A so called 'Smartbook'.

Interesting articles on power management/consumption under Linux and how to re-pack a laptop battery.

Disabling cores doesn't really help with power saving and may even increase it in some cases.

Disappearing Optical Drive Fix