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Appliance repair hazards


The main hazards in appliance repairs are summarized. There are always
others that have the potential to occur too.


==Common risks==
Some risks are common to all mains appliances:
* shock if plugged in
* basic wiring faults

==Microwave==
These are one of the highest risk domestic appliances to repair. The
EHT supply in particular tends to be fatal if touched, and has killed
experienced technicians.
* EHT supply for magnetron
* Parts connected to EHT supply: LT magnetron supply wires,
transformer, capacitor, rectifier
* Power supply capacitors sometimes store thousands of volts even when
unplugged
* Misalignment or miswiring of interlock switches
* Failed shorting resistor when replacing [[fuse]]
* Microwave leakage after replacing a component
* Microwave leakage from rust holing
* Sharp edges

===Old microwaves===
Old machines from the beginning of the '80s and before can have:
* unsafe interlock system.
* carbon loaded rubber seals prone to coming adrift, permitting
leakage

Some 1970s and earlier machines have power controls that switch the
EHT directly, making all internal parts of the power control and
associated wiring dangerous to touch until the EHT has been fully
discharged.

Commercial machines from the 1960s and before are uncommon, but do
exist, and in a minority of cases can continue cooking with the door
part way open. These are hopelessly unsafe.

===Damaged microwaves===
The mains risks a
* missing or damaged door grille cooks the user
* warped door
* missing seals on old machines
* damaged door hinges
* door misalignment


==TV==
===CRT TV===
* Power supply capacitors store hundreds of volts even when unplugged.
This voltage is distributed around some parts of the circuit board.
* EHT supply, stored by the picture tube when off
* Focus voltage, also stored
* Propped appliance can fall on child or pet
* Picture tube may explode if the unprotected thin rear of the tube is
broken

===LCD TV===
* Power supply capacitors store hundreds of volts even when unplugged.
This voltage is distributed around some parts of the circuit board.
* High voltage stored in lighting invertor
* Weak thin glass: screen and backlight

===Antique TV===
Just a note that very old TVs are somewhat different to modern kit,
especially in picture tube safety. Old picture tubes from the 1970s
and earlier may lack a rimband, resulting in explosion if the tube's
reinforced front glass is broken. Older pre-1960 picture tubes that
use a separate plate glass shield to protect them are both fragile and
explosive, and require treating with respect.

The EHT supplies in historic TVs can bite, but are normally safer than
modern sets, and pose little risk to life. The exception is rare pre-
war sets, which often contain a dangerous type of EHT supply.


==Washing machine==
* Mains filter sometimes stores mains voltage after the machine's
unplugged.
* Power supply for controller stores mains voltage when unplugged
* Hand can get caught in mechanical parts
* Ill fitting spanners can slip, causing minor injury


==See Also==
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]



[[Category:Appliances]]
[[Category:Electrical]]
[[Category:Fault Finding]]
[[Category:Repair]]
[[Category:Safety]]
[[Category:TV]]