6. Common Trouble Shooting
No.
1
2
3
4
5
6
Failure
Liquid crystal
screen is not lighted
When ocular visibility
is adjusted, ocular
dividing plate cannot
he seen clearly
Drone can not be
seen
Drone is not clearly
seen
Excursion of drone
center
Shifting of
dot-making
mechanism
Reasons of Failure
Lamp is not lighted
Degree of testee’s eyes is
too deep or he (she) has
astigmatism
Lamp is lighted
Dustproof shield is not
removed
Dust on optic lens
Lock screw is loosened
Limit screw is loosened
Connecting screw is
loosened
Solutions
Switch on power
supply
Wear spectacles
Switch on power supply
Take off dustproof
shield
Clean it with absorbent
cottondipped with
cleaning solution
Take off measurement
bearing seat, and
adjust and tighten 3
lock screws
Adjust and tighten
limit screw
Adjust and tighten
connecting screw
19
dipped with mixed solution of ethanol and aether.
Matters Needing Attention
For cleaning the device, do not use organic solution such as paint thinner, otherwise
surface of the device will be damaged.