Tips on buying a used laptop - Part I

This question came up in one of the forums I frequently follow (from a programmer; programmers don't understand shit about hardware. They just code, they are not even IT, although HR departments usually confuse the two !)

Buying a 2nd hand laptop is always a big challenge. The reason is, noone really sells a laptop unless there's something wrong with it. Its not very common to see laptops on sale because of old age. If you are lucky, you may find one of the leased machines that has been returned to the financial institution. But, even that is risky as those are sold in bulk in auctions (and seller do not allow you to even touch the machine and are sold "as is" or "WYSIWYG". 


Advantages and Disadvantages
OK, you may not have the funds to buy a brilliant and high performance machine, but having a low performance but brand new laptop has it's advantages against the high performance but old machines. 

Things you need to know (that noone will ever tell you)
Unlike many bloggers, I will start with the disadvantages which may sound intimidating but will prove worthy:

1. Noone sells an old portable computer just because it got "slow"; some do, but the chances of catching one of those is pretty slim. So, there much be a "catch". It might be a defective component or worn out component such as the battery, hard disk, memory or worse the mainboard. Good news is, though sellers do their best to camouflage the defects deep, it is possible to spot them. Bottomline, there's no virgin laptop.
    
2. Unlike desktop computers, portable machines are more vulnerable to mishaps and accidents. A laptop get's dropped on hard surface at least 3 times in it's life cycle. Hard drops usually invisibly damage the hard disks, as the hard disks are the weakest component in portable machines (does not apply to SSDs, I will mention them soon). Hard disks are made of few magnetic platters spun by a tiny electric motor whilst a very sensitive head moves back and forward to read and write the data on it). Also as their function is mobility, they are used many environments, which some of them can be quite risky.
   
   Though many believe the life of a HDD is calculated by the amount of warranty length, by looking at it's MTBF specification by the manufacturer may actually give to a good insight on the predictability of the reliableness of the component. (MTBF: Mean Time Between Failure is an engineered rating that shows the reliability of the hard disk).
   
   Though MTBF values aren't advertised in the open, it is usually available from the vendor websites' technical specification leaflets.
    
3. As the technology trend enforces devices to be more miniature, robost and more mobile, devices reduce insize; not by miniaturization but by sacrifice. Yes, sacrifice of precautional elements inside the devices. For example, before the 2000's most laptops were heavy and chunky. The reason for that was that under the cover there were certain precautionary measures to ensure the durability of the system, such as aluminium skeleton to improve durability against falls to protect mainboard and LCD screens from getting wrecked or component bay doors to allow parts to be upgraded or changed. But, just like in our great looking but worthless cars, everything these days are engineered not for the durability, but the cost.
   
   Engineers has been convinced by the sales people that it is cheaper to replace the whole thing instead repairing components; even if you tried to repair a new laptop that has been damaged, you probably will not be able to reach the required parts for reasonable prices. So, the lesson is newer it is, less durable it is. Even the hard disks have less protective insulation in them these days. That's why they are so thin, so fragile and short lifed.
   
   So, best lifetime of a laptop of today's tech is around 2-5 years. That's if it doesn't get damaged by a short circuit or a fall. Oh yes, I have to mention this ! The old laptop power adapters were big and chunky. The main reason for it is the wattage. Today's laptop adapters are usually much smaller in size but the wattage is much lower too. Also less reliable as they are more vulnerable against power surges (a power surge generally fries the laptop's mainboard. It happened to me twice).
    
4. The screen: Though tech hasn't changed much on the screens in the last decade; other than the new 4k monitors, it is still the most fragile component. It's life is not longer than 1-5 years at most; really depends on the usage and production quality. As the bezels are so thin, they are more vulnerable against damage. Also as the new LCD panels are so thin, they get damaged VERY easily and no, it's non-repairable. But good news is, there are lots of OEM's that screens can be purchased online from resources such as AliExpress and replaced by people like myself. Most frequent sign of defect in LCD panels are dimm lights, stratches of screens, inequal light patches on screen (CAUTION: This means the screen has been smacked or damaged!) or missing pixels; dead pixels in the screen, which can be usually seen on white backgrounds.
    
5. The Battery: An optimal battery life of a laptop is around 1-5 years, depending on the usage. Machines that have been used offline tend to have longer lasting batteries, whilst the machines that have been hooked up to a constant power resource, tend to eradicate faster. Battery units are made up of parallel connected cells. Higher the number of cells, higher the long livety and the performance of the battery is. Generally 6 cell batteries are the best.
   
   There are hundreds of OEM brands which claim their replacement battery is the best with low prices, but it's generally a fake information. OEM batteries do not last as long as the originals ; even might be out of specification that may damage the system. 

continued on part 2 soon.