Why do computers fail (Electronically)
Any Circuit the is connected to the Outside World or is Actuated by People.
Power Switch Dirty Contacts.
Power Socket/Plug Dirty Contacts, Dry Joints, Wrong Voltage Applied.
Keyboard Dirty Keyboard Contacts, Dirty Ribbon Contacts.
Expansion Connector Dirty Contacts, Blown Gates, Poorly constructed Cable.
Floppy Connector Dirty Contacts, Blown Gates, Poorly constructed Cable.
Printer Connector Dirty Contacts, Blown Gates, Poorly constructed Cable.
Joystick Connector Dirty Contacts ElectroStatic Discharge from monitor, Blown Gates,
Dry Joints.
Video Connector Dirty Contacts, Blown Gates, Dry Joints.
Audio Socket Dirty Contacts, Dry Joints.
Volume Control Dirty Wiper Contact.
Floppy Drive Dirty Media, Dirty Head, Out of Alignment, Belt.
Tape Drive Dirty Media, Dirty Head, Azimuth out of alignment, Belt.
Thats not much to go Wrong !
Ray
If anybody can add to the list Please contribute.
Thanks Ray
On the electronic side I'd add:
Electrolytic capacitors have a given lifespan. Many work well beyond this, but if the system was exposed to heat (mainly self created heat) or the capacitors were being fed with "dirty" (lots of spikes) voltages then the lifespan will be greatly reduced.
Passive components such as resistors and ceramic capacitors can last for centuries, the only thing that damage these are physical damage or if they were running outside their limits due to something else having failed.
TTL IC's are also pretty robust, but they only work between 4.75V and 5.25V. If the capacitors are getting old and the chips are regularly getting spikes above 5.25V they can die too.
Custom IC's such as the Gate Array. These were manufactured using a masking method that tends to be less robust than standard IC's. If there are weak junctions within the die, they can also fail when the junction gives up.
Another failure that the CPC luckily doesn't really suffer from is static discharge problems. On computers like the spectrum 48K, the computer was often being used on the carpet in front of the TV. Moving the computer or yourself on carpet causes huge charges to build up. As the expansion port is directly connected to ESD sensitive IC's, touching the contacts could result in instant death of your Speccy. The CPC tended to be used on desks due to it having its own monitor, inadvertantly reducing this ESD problem significantly.
Bryce.
Anything made by man is imperfect. Anything mass produced at low cost by man is far from imperfect. Consumer rated parts (that make up items that people buy) is at a lower level than that!
There are many reasons why a system or part may fail. These include, but are not limited to:
- Poor quality of design of the system (this may not be intentional, but problems may be found after manufacture/sale).
- Poor quality of the design of the parts / components (this may not be intentional, but problems may be found after manufacture/sale).
- Poor quality control.
- Natural degradation of the components, including unknown contamination of the silicon, tin whisker growth, degradation of the thin metal interconnects inside chips (the current flowing through thin metal conductors can damage them, eventually resulting in complete failure of the conductor), loss of electrolytic from capacitors, leakage from cells and batteries, wearing out of cells and batteries, changes of the values of resistors (carbon film) and capacitors.
- Heat damage (either used in too hot an environment, poor ventilation, or heat generated within the component or within the system). Also heat cycling is a know cause of system failure, due to the repeated contraction and expansion
- Wear / movement of connectors and moving parts, including user controls (pots, switches, buttons, keys).
- Damage from malfunctioning power systems.
- Damage from external systems (excessive voltage from connected devices like your TV, or external devices drawing more current than the system can safely handle), either due to their design or due to a malfunction.
- User misuse (including wrong power supply type / voltage / polarity).
- Electrostatic discharge.
- UV light damage.
- Breakdown of the chemical structure of the components (for example, some rubber and plastic parts).
- Exposure to a wet or damp environment causing corrosion, rot or mold. Some insulating components can also adsorb water which affects the insulation's voltage rating (causes electrical leakage currents to flow).
And I'm sure I've left some out...!
Mark
No, other than natural disasters and alien invasion that list is pretty much complete :D
Bryce.
Quote from: Bryce on 12:19, 11 November 16
No, other than natural disasters and alien invasion that list is pretty much complete :D
Bryce.
Talking of alien invasion, that reminds me that at work early this year, in a remote equipment cupboard located in the countryside, we kept having an important communication system fail.
The cupboard contained a repeater amplifier system. A rodent (we think a field mouse) liked the warmth of the equipment. But it kept nibbling at the wiring inside the amplifier module causing repeated failures of the replacement modules on a weekly basis. Well, until we finally managed to block up all the possible entry holes and put bate down...
Mark
Ah, that reminds me of one common failure that comes up quite often: Insects and small animals. Not really a problem in retro computers, but often found as the culprit in heating controllers, alarm systems and even coffee machines. Just recently I had to fix a power supply which had died when a Gecko decided to crawl into it. Unfortunately the Gecko bought it too.
Bryce.
QuoteAh, that reminds me of one common failure that comes up quite often: Insects and small animals.
Ah yes, that reminds me of what happened a few months ago. We were away and had some friends looking after the house. My mate called and said the PS4 was fizzing and refused to come on. Since he has zero technical expertise I told him to unplug it and just use the PS3 instead.
When I got back later that day, on taking it apart I found a slug had very neatly placed itself between the live and neutral inputs of the transformer. Sadly it didn't survive, but remarkably the PS4 supply wasn't damaged. After a thorough clean of the circuit board (slugs are amazingly slimy) the system powered on as normal. The slug had been acting as a huge resistor which prevented enough power from getting through in order to start the machine. Quite how it managed to crawl through the relatively narrow air vents remains a mystery....
Quote from: Bryce on 13:08, 11 November 16
Ah, that reminds me of one common failure that comes up quite often: Insects and small animals. Not really a problem in retro computers, but often found as the culprit in heating controllers, alarm systems and even coffee machines. Just recently I had to fix a power supply which had died when a Gecko decided to crawl into it. Unfortunately the Gecko bought it too.
Bryce.
That reminds me of the spider nest in the Olson amplifier I repaired not so long ago...
This thread remember me what happend years ago here in a regional tv station in directe :) . This cause is not listed.
Periodist bad day :D .
This time she not have computer but its funny to view it :
Quote from: Bryce on 13:08, 11 November 16
Ah, that reminds me of one common failure that comes up quite often: Insects and small animals. Not really a problem in retro computers, but often found as the culprit in heating controllers, alarm systems and even coffee machines. Just recently I had to fix a power supply which had died when a Gecko decided to crawl into it. Unfortunately the Gecko bought it too.
Bryce.
Hi Bryce
We have a Verrrry old Electric hot water heater up in the roof.
The thermostat stopped working Because you could not have got 1 More Dead ant in the relay contact area.
They ended up opening the contact permanently until i removed them .
Ray
Also 99% of non electronical failures are situated between the keyboard and the Chair..
True :D
Since you have alien invasions and the likes in the lists, I think you all forgotten two of the biggest menaces: mothers and wives.
There, now it's complete.
T
PS mice have been plaguing machinery for a long time; there are lots of recorded incidents of incapacitated German tanks on Russian territory, their wiring chewed by country rats.
Sorry I thought you were referring to the Moth Computer Bug?
(http://2.bp.blogspot.com/-stAU_P2M-vI/UCyJ3pZ932I/AAAAAAAAAx4/cOHr4UAEpCU/s1600/120816-0001.jpg)
Actually Weasels are the big problem in Germany. They regularly chew through the wiring in vehicles if you live in the countryside.
Bryce.