This document is written in English for overseas OMs. -DS1ORJ-
LCD contrast of TH-9800 is too low.
Almost invisible when viewed from upper side.
It cannot be adjusted in the menu.
In the circuit it is set to a fixed value.
I read an idea about it on some forum.
Then I changed the value and it worked.
VLCD is the voltage that adjusts the contrast.
Low voltage means high contrast.
High voltage is low contrast.
0V(GND) shows too strong contrast to almost invert the LCD.
There is a resistor on the front panel.
R1656 is 120K too large.(VLCD too high)
A value of 10 to 56 K ohm seems appropriate.
(it will depend on the environment temperature)
For the work in progress photo.
It looks good enough from the front. very good even in sunlight.
Good luck.
73.