Display (Lcd); Switched Capacitor Filter Controls - Welch Allyn Grason-Stadler GSI 17 Series Service Manual

U511 Timer
TMRO
TMR1
TMR2
Front Filter
Panel/ Cutoff
Freq Freq
125 150.38
250 300.75
606.06
500
750 909.09
1000 1176.47
1500 1818.18
2000 2500.00
3000 3333.33
4000 5000.00
8000.00
6000
8000 8000.00

8.7 DISPLAY (LCD)

The LCD is a reflective 3-1/2 digit Liquid Crystal Display. It
is the largest indicator on the GSI 17, and it is used for a
variety of purposes.
possible error messages in the Normal Mode, along with SPL and
A/D numbers in the calibration and Diagnostic Modes.
each mode's functional description for detail).
An LCD segment is energized only when there is a 5 Volt potential
across it. To confirm if a segment is receiving the
drive signal,
signal and CH2 to the segment drive signal.
the signals should be out of phase, therefore applying
across it.
Signal
Name Direction
SQWIN OUT
SCFCLK OUT
CLKGEN OUT

SWITCHED CAPACITOR FILTER CONTROLS

Switched
Capacitor
SCFCLK (Clock)
Freq
15,038
30,075
60,606
90,909
117,647
181,818
250,000
333,333
250,000
400,000
400,000
Some purposes are:
connect CH1 of an oscilloscope to
Description
8254 Counter 0 Used for
the Oscillator SWQIN
Frequency =
Clock.
Stimulus Frequency 8254
Counter 1 Used for the
Oscillator Switched
Capacitor Filter SCFCLK.
(see the following table
8254 Counter 2 Used to
Produce the 2 msec Time-
base.
Timer
50/100
Setting State
266.00 0
133.00 0
0
66.00
44.00 0
34.00 0
0
22.00
16.00 0
0
12.00
16.00 1
10.00 1
10.00 1
indication of HL and
For an "ON"
Antialiasing
AAFIL
State
0
0
0
0
1
1
1
1
1
1
1
(Refer to
appropriate
the
backplane
segment
5 Volts
BP/
LP
0
0
0
0
0
0
0
0
0
0
1