VOLTAGE ANALYSIS OF ANALOG SECTION
Proceed with the voltage analysis only if the resistance readings were satisfactory. The values given below
are approximate.
The following measurements will be taken from the copper side of the PC board. Turn the unit on and place it
upside down.
See Figure J for locations of the testing points.
From
To
Circuit
Volts
Volts Measured
Pin 4 (U6)
GND (B1)
U6 Vcc
+12V
Pin 12 (U6)
GND (B1)
U6 GND
-12V
Pin 7 (U10)
GND (B1)
U10 Vcc
+12V
Pin 4 (U10)
GND (B1)
U10 Vcc-
-12V
TESTING THE FUNCTION GENERATOR
Note: Use the knobs when turning the switches.
TESTING THE SINE WAVE
1. Set your meter to the 200mV DC range.
2. Connect the red meter lead to the 4 pin breadblock marked FREQ and the black lead wire to the 4 pin bread-
block marked GND.
3. Set the WAVEFORM knob to SINE, COARSE FREQUENCY knob to 1K and the FINE ADJ and AMPLITUDE
knobs fully clockwise.
4. Set the DC offset to the middle position. Then, turn on the trainer.
Turn unit right side up.
Figure J
-32-
1
2
3
4
5
6
7
8
10
9
11
12
13
14
15
16
1
2
3
4
8
7
6
5
U10
U6
12
4
4
7
Summary of Contents for XK-550K
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Page 50: ...SCHEMATIC DIAGRAM 49 ...