Key Board; Panel Board; Encoders; Touchscreen Interface - LeCroy WaveSurfer 400 Series Service Manual

4.5.1 Key board

The front panel assembly consists of the panel board PCB, the panel board metal,the
elastomeric keypad and the key board PCB. The key board PCB connects to the panel
board assembly which is connected to the mother board by USB. The key board has the
LED's which illuminate some of the front panel buttons and has trace patterns which act
as switches when the elastomeric keypad shorts the traces together in response to a key
press.
The key board has configuration jumper which must be selected based on the
identification of the front panel (2 channel model or 4 channel model).

4.5.2 Panel Board

Panel board consists of rotary encoder function and touchscreen function.
The encoder status, the front panel key status and the touch panel status is read by the
front panel processor, the H8S2212. Power for the panel board comes from the cable of
the USB.

4.5.2.1 Encoders

4.5.2.2 Touchscreen Interface

4-14 Theory of Operation
The panel board contains all of the rotary encoders. There are two different
types of encoders on this assembly, some have a push switch, others do not.
The V/Div and timebase use encoders that do not have push switch, the rest
of the encoders have a push switch. The encoders contain two switches, they
are not potentiometers. The software can determine the direction and speed
the encoder is turning based on the order and frequency of make and break
connections of these internal switches.
Provides a control interface to a 4-wire resistive touchscreen. The pointing
location is measured by 4 A/D convertors in the front panel processor.