Heathkit TA-16 - Page 38

Page 34
DIFFICULTY
POSSIBLE CAUSE
No tremolo with
1.
Resistor R67 open.
foot switch not
2.
Faulty zener diode Dl.
plugged in.
3.
Defective component or wiring error in stages Q12 or Q13.
4.
Defective LDR.
5.
Incorrect wiring of foot switch jack.
No reverb with
1.
Defective reverb cable.
foot switch not
2.
Incorrect wiring of foot switch jack.
plugged in.
3.
Defective component or wiring error in stages Q11 or Q5. Make
point-to-point hum test. See Page 35.
4. Defective reverb unit. NOTE: If stage Q5 was OK in the point-to-
point hum test, the reverb unit can be checked by tapping on its
metal chassis with the Reverb Volume control rotated fully clock-
wise. This should result in a loud banging noise from the speaker.
5. Cardboard still in reverb unit.
Distorted sound.
1. Controls set too high.
2.
Incorrect bias on transistors. Check collector voltages.
3.
Shorted coupling capacitor.
4.
Defective speaker.
Excessive hum 1.
Place On-Off-On switch in the other ON position.
with musical 2.
Check for faulty ground connections.
instrument
3.
If excessive hum stops (some hum will be normal) when musical
connected,
instrument is disconnected, check instrument wiring, connecting
cable, and pickup heads.
4.
Move the instrument further away from the Amplifier, or change
the angle between it and the Amplifier.
High hum with no
1.
Place On-Off-On switch in the other ON position.
musical instru- 2.
Check for wiring errors or faulty ground connections.
ment connected.
3. Faulty filter capacitors; C34 through C37, or C104.
4. Connecting cable between reverb unit and amplifier open or shorted.
5.
Shield lead to lug 4 of double phono socket E is touching the
chassis or a mounting nut.
6.
The outside of the connector on one of the reverb unit cables is
touching the rear of the chassis.
7.
Reverse line plug in AC outlet.
One or both foot 1.
Wiring error in the foot switch or plug, or in amplifier foot switch
switches inoper- jack.
alive.
2.
Faulty cable on foot switch.
3. Defective switch.
'
Very little bass with
distorted output.
1. Speakers connected out-of-phase with each other.
Amplifier howls
continuously
with reverbera-
tion turned on.
1.
Reverb control set too high.