Teac A-650 - Troubleshooting Guide for TEAC A-650; Tape Transport Section Troubleshooting; Amplifier Section Troubleshooting

9. TROUBLE-SHOOTING
TAPE TRANSPORT SECTION AMPLIFIER SECTION
1.
1.
2.
3.
2.
4.
3.
5.
6.
35
Fuse blows when POWER is switched ON.
- Defective Power Transformer
Auto End-stop will not work in Play and/or Fast Wind.
- Defective Transistor Q529
- Defective Diode D533
- Defective Capacitor C5 12
- Defective Resistor R564
- Defective Parts associated with Hall Effect Element
Capstan does not rotate
- Capstan Belt off
- Defective Motor
- Defective Switch S509
Excessive Wow and Flutter
- Defective Pinch Roller, Pinch Roller pressure incorrect
- Capstan Belt stretched or oily
Index Counter will not count
- Counter reset button not fully depressed.
— Counter Belt off
VU Meter will not indicate in playback mode
- Defective VU Meter
- Defective Transistor Q761
- Defective Semi-fixed Resistor VR103. VR104
- Defective Parts associated with parts indicated above
Loss of high frequencies in playback mode
High frequencies too low
- Defective Transistor Q 102
- Playback equalizer circuit wrong
High frequencies arc several dB below specified response limits
— Head dirty or defective
Loss of high frequencies including level variation
- Improper hcad-to-tapc contact
- Unstable functioning of tape transport mechanism
Does not record
Can record when changing Bias Switch setting
- Defective Bias Switch
— Defective Trimmer Capacitors VC602, VC604, VC606
- Defective Parts associated with parts indicated above
Cannot erase, also
- Bias Oscillator Ass ’ y faulty
Can erase - sound from record monitor mode is normal
- Head dirty
— Defective Switch S301
— Defective Circuitry of IC102, QI 13, QI 14
Poor playback signal-to-noisc ratio
Excessive hum - reduced when changing Power Transformer
- Defective Power Transformer
Excessive white noise (hiss and circuit noise)
- Defective Head
- Defective Transistor Q101 , Q102
- Associated circuitry of Transistor Q101 , Q102
Wave form varies continuously
- Defective Transistor QI 01, Q102
- Defective Capacitor Cl 02, C108
- Defective Parts associated with parts indicated above
Tape winds onto Capstan Shaft
— Defective Pinch Roller
- Defective Take-up Reel Table Ass ’ y
- Idler slipping
- Tape path wrong (improper Tape Guide position, bad
Head mounting)
NOTE
REF. No ’ s indicated in the following table refer to the left channel.
For the right channel REF. No. identification, see schematic
Diagram.
No sound in playback mode
Noise (hum or clicking noise) appear when touching head
wires.
- Poor soldering of head terminations
- Defective Head
Sound can be heard during recording
- Defective Switch S301
- Defective Transistor Q101.QI02. Q103
- Defective Parts associated with parts indicated above
Sound cannot be heard during recording
- Defective Transistor Q 1 0 1, Q 102, Q 1 03 . Q 1 09
- Defective Dolby NR Circuit
- Defective Parts associated with parts indicated above