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S Y M P T O M
1. DC Offset:
2. High Current:
3. Oscillation:
Unloaded
Loaded
4. Excessive Noise:
5. No Bias Adjustment:
6. Incorrect Frequency
Response:
7. Excessive Distortion: Defective Q7, Q8, Q25
TROUBLESHOOTING GUIDE
≤2v
Defective U1
Defective Q1
≥2v
Defective U1
Defective CR1, 2, 6, 15
Open ground at the RCA
input jack
Defective Q1-8, Q24
Defective CR16, 17
Short between transistor
and heat coupler
Shorted driver or output
transistor
Defective C5
Defective Q6, Q9
Defective CR8
Open C4, 5, 9, 11
Defective R24, 29, 30,
51, 52
Defective U1, Q1
Defective R57, 58
Defective Q4, 6, 7, 9
Open R11, 12, 13
Defective C5, C8
Shorted Mica Insulator Q3
Defective CR18, 19
Defective CR5 ( at full
output only)
POSSIBLE CAUSE
Test point "A" polarity
the same as DC offset
(see Figure 11)
Test point "A" polarity
opposite to the DC offset
(see Figure 11)
Trouble shoot (by removing
collector screws) in this
sequence.
Negative: Q9, 11, 23, 21,
22, 19, 20, 18
Positive: Q6, 10, 17, 16,
14, 13, 12, 15
23
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