Editing Category:Common Issues (section)

==== Miscellaneous Components ====

* '''Relays''' (component designation K, sometimes) are isolator switches. These are generally usually used to protect a subsystem from some signals (power rails or high voltage) until some criteria has been met (like transient voltage spikes during startup). These have a normally open (NO) and normally closed (NC) state. Verifying these work is a matter of checking the input signal and seeing if the output is switching between the open and closed states.[[File:Fuses.png|thumb|Fuse symbols.]]
* '''Fuses''' (component designation F) are used to protect the circuit in case of failure from over-current. They are made from a small film or wire that has a current rating matching the rating of the fuse, and the part will fail open circuit (OL) if the current through the part is exceeded. These are generally located around power supplies, laser diodes, and backlight drivers. The only measurement you need to take to verify that the part is working as normal is to make sure it reads under a few ohms.
* '''Connectors''' (component designation J) are physical connectors. when these fail it usually is from a pin getting bent, or something like that. It's different from connector to connector. It is also possible in the case of chemical spills for the plastic in the connector to become slightly conductive and leak signals from one pin to another, although this is a bit more uncommon. Usually a visual inspection is enough to tell if the part is good or not.