Motorola HSN4035 Service Instructions Manual page 13

Potentiometer Knob Slowly
From Fully Counterclockwise
Perform Procedure Titled
Replacing Volume
No
Potentiometer, If That Does
Not Repair Fault, Perform
Procedure Titled
Replacing PCB.
Notes:
1. All specified voltage, current, and resistance values have a tolerance
of 10% unless indicated otherwise.
2. Signal between TP8 and TP2 has a DC offset of approximately +160mV.
3. Signal between TP10 and TP11 has a DC offset of approximately +6.1V.
START TEST
1. Turn Off Power Supply.
Any
2. Perform Procedure Titled
No
Sound Output
Separating Front and
From
Rear Housings.
Amplifier-Loudpeaker?
3. Turn On Power Supply.
Yes
1. Turn Off Power Supply.
2. Perform Procedure Titled
Separating Front and
Is
Rear Housings.
Sound Output
No
3. Disconnect One Speaker
Undistorted and About
Lead at Speaker End.
Normal Listening
4. Connect a 4-Ohm
Volume?
Resistor Between TP10
and TP11 on PCB.
5. Turn On Power Supply.
Yes
Rotate Volume
Position to Fully
Clockwise Position.
Does
Volume Potentiometer
Adjust Sound Output
Smoothly Over
its Entire Range?
Yes
No
Is Sound
Output Undistorted
At All Settings
of Volume
Potentiometer?
Yes
Amplifier-Loudspeaker
Is In Good
Operating Condition.
End of Test.
Is
13.8Vdc
No
Present Between Terminals
TP12 (+) and TP13 (-)
on PCB?
Yes
Is
1-kHz 230mVrms
No
Signal Present Between
TP1 and TP2 (Rtn)
on PCB?
Yes
Is
1-kHz 220mVrms
No
(440mV p-p) Signal Present
Between TP7 and
TP2 (Rtn) on
PCB?
Yes
Is
1-kHz 180mVrms
No
(320mV p-p) Signal Present
Between TP8 and TP2 (Rtn)
on PCB?
(Note 2)
Yes
1. Turn Off Power Supply.
2. Disconnect One Speaker
Lead at Speaker End.
3. Connect a 4-Ohm Resistor
Between TP10 and TP11
on PCB.
4. Turn On Power Supply.
Is
1-kHz 3.2Vrms (8.8V p-p)
No
Signal Present Between
TP10 and TP11 on PCB
(Note 3)?
Yes
1. Connect Distortion Analyzer
Between TP10 and TP11 on PCB.
2. Rotate Volume Potentiometer
Knob Slowly Over its Entrire
Range.
Is
Harmonic Distortion
No
of Signal Between TP10 and
TP11 5% or Less for
All Settings of
Volume Pot.?
Yes
Perform Procedure
Titled Replacing Speaker
Perform Procedure Titled
Replacing 9-Foot Cable.
If That Does Not Repair
Fault, Perform Procedure
Titled Replacing PCB.
Perform Procedure
Titled Replacing PCB.
Perform Procedure Titled
Replacing Volume
Potentiometer.
If That Does Not Repair
Fault, Perform Procedure
Titled Replacing PCB.
Perform Procedure
Titled Replacing PCB.
MAEPF-26581-O