WARNING
THIS SECTION OF THE M A N U A L
CONTAINS SERVICE INSTRUCTIONS
FOR USE BY QUALIFIED SERVICE
PERSONNEL ONLY.
Instrument Type
Required Characteristic
Recommended Instrument
Test Oscillator
Frequency Range: 20 Hz- 20 kHz
Distortion: < 0 . 0 0 1 %
Output: 1 V RMS Min.
Sound Technology
Model 1700 A
Distortion Analyzer
Measurable to 0.002%
Sound Technology
Model 1700 A
Multimeter
Accuracy: 0.1% r 1 digit
DC Range: ± 199.9 mV to ± 1199 V
Resistance: ± 0 . 2 % of r 1 digit
Input Impedance: 10 M O
Fluke Model 8000A
Output Load Resistors
100 W, 4 H a n d 8 a Non-inductive Type, 1%
DaleNH-100
Resistor Decade Box
1 0 - 1 k O M i n .
Variable Autotransformer
Capable of supplying Min. of 5 0 0 W over a range of 9 0 - 1 3 6 V.
1. If autotransformer does not have an AC voltmeter to indicate
output voltage, monitor the output with either a multimeter or AC
voltmeter.
2. If autotransformer does not have a watt meter, a watt meter
capable of indicating 15 - 270 W will be required.
GenRad W5MT3W
Recommended Test Equipment
The following test procedures are required after an IC,
driver transistor, bias network diode, thermistor, or
output device is replaced:
Bias Adjustment
Verify that the distortion at 20 kHz, 200 W, is the same
as 20 kHz at 1 W and that the stable idle power is
3 0 - 4 0 W. If not, the following procedure is required:
1. Substitute resistor R37 with a decade box.
2. Adjust the amplifier for 1 W at 20 kHz.
3. Adjust the decade for minimum distortion and sub-
stitute R37 with the closest EIA standard resistor.
4. Verify distortion at 200 W and 1 W.
NOTE: Amplifier must be warm before performing
distortion measurements or adjustments.
DC Offset Adjustment
Connect the multimeter to test point #2 on the circuit
board. With the meter set at the lowest DC voltage
range (mV), adjust the DC NULL control, R10, for a
minimum DC voltage, 0 ± 25 mV.
NOTE: Amplifier must be warm before making
adjustments.
Installation of Optional Output Transformer
[option on 6022}
To install the optional output transformer, Figure 5,
(Model No. 60-6022):
1. Remove the heat sink/circuit board assembly.
2. Place the optional output transformer in the corner
of the chassis and secure it at the four holes in the
bottom of the chassis with the hardware provided.
3. Attach the Molex connector to the mating connector
of the amplifier.
4. Remove the cover over the cutout for the TRANS-
FORMER OUTPUT terminal strip. Slip the new
terminal strip of the output transformer through the
cutout and orient it so that the GRAY wire is the
COM. Screw the terminal strip in place with the
screws that held the cover.
NOTE: If the output transformer is to be used, install
a LINK between LO and HI of the DIRECT OUTPUT
terminal strip, Figure 1.
14 dB Additional Gain Conversion
14 dB of additional input sensitivity, using the optional
JBL Model 5195 matching/bridging transformer, can
be offered to the user by removing the RED wire con-
nected to pin #8 of the 9-pin receptacle, XK301, and
reconnecting it to pin #7.
20 kHz Equivalent
Bandwidth Filter
INPUT
OUTPUT
