TB 9-6625-1976-24
Table 4. Distortion
Test instrument
Audio analyzer indications
FREQUENCY
FREQUENCY
VOLTAGE
VOLTAGE
RANGE
RANGE-HZ
dials
dials
standard
No load
With load
switch settings
switch settings
(V)
(Hz)
settings
(%)
(%)
( )
(V)
100
20.0
1
1.000000
---
<0.081
---
100
K
20
K
1
1.000000
20
<0.041
<0.1
100
K
50.00 K
1
1.000000
20
<0.041
<0.19
100
K
20
K
10
10.00000
200
<0.041
<0.046
100
K
50.00 K
10
10.00000
200
<0.041
<0.055
100
K
20
K
100
100.0000
---
<0.041
---
b. Adjustments
CAUTION
In the following check, TP4 and TP5 are floating at
approximately + 190 V dc above chassis ground. Isolate the
multimeter from chassis ground and use appropriate
precautions.
(1) Connect multimeter between A7TP4 (LO) and A7TP5 (HI) (fig. 1) of the power
amplifier board.
(2) Set FREQUENCY RANGE-Hz switch to 100 K and FREQUENCY dials to
100.00 kHz.
(3) Set VOLTAGE RANGE switch to 100 V and VOLTAGE dials to 10.0000 V.
(4) If multimeter does not indicate between 0.34 and 0.36 V dc, adjust A7R26
(fig. 1) for multimeter indication of 0.35 V dc (R).
(5) Set FREQUENCY dials to 50.00 kHz.
(6) Measure distortion. Adjust A9R31 (fig. 1) for minimum distortion (R).
(7) Connect multimeter to TI OUTPUT and SENSE terminals, using two cables.
(8) Set FREQUENCY RANGE-Hz switch to 1 kHz and FREQUENCY dials to 1.0 K.
(9) Set VOLTAGE RANGE switch to 10 V, VOLTAGE dials to 10.00000 V and
SENSE switch to EXT.
(10)If multimeter does not indicate between + 100 V dc, adjust A7R6 (fig. 1) for a
within-tolerance indication (R).
10. Voltage Accuracy and Linearity (Reference Level Only)
a. Performance Check
(1) Connect TI OUTPUT and SENSE HI terminals to the ac measurement
standard INPUT 2 HI terminal and connect the TI OUTPUT and SENSE LO terminals to
