Philips PM3055 Operation Manual page 28

3-14E
3.3
3.3.1
3.3.2
PRINCIPLE OF OPERATION
This section describes the principle of operation and should be read in conjunction with the overall block
diagram (see Appendix B).
The oscilloscope circuit consists of five functional main sections:
— Control section (see section 3.3.1)
— Vertical deflection — (see section 3.3.2)
— Horizontal deflection (see section 3.3.3)
— CRT display section (see section 3.3.4)
— Power supply section (see section 3.3.5)
Control! section
The knobs in the key-matrix on the front panel drive the various circuits via the software control lines. These
lines are generated by the microcomputer, which also drives the L.C.D. (Liquid Crystal Display) for the
correct knob and control setting indication.
' AUTO SET enables vertical and horizontal functions to be set depending on the vatue of the input signal.
MENU permits checking of all possible knob setting with their L.C.display.
The continuous controls and the knob LINE ON are directly connected to their control circuits (no REMOTE
control facility).
Vertical deflection
GND 2 , :
AC/DC \ input signal coupling
V—mV Vertical deflection coefficient
VAR Continuously-variable attenuation control UNCAL indicated in LCD
INV (only ch.B) Input signal inversion
A channel A only
B channel B only
A and B channels A and B displayed together.
ALT or CHOP mode is selected by its softkey.
TRIG VIEW MTB Trigger signal displayed.
The DELAY LINE permits the viewing of leading edges of fast input signals.
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