Teac A-650 User manual

• ■
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HMM
TEAC
Stereo Cassette Deck with Dolby System
GENERAL INTRODUCTION
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NOTE
When ordering replacement parts, please refer to the
PARTS IST which is printed separately from this
manual.
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; TEAC CORPORATION [
51031740
If any of the adjustments or repairs seem too complicated
or are difficult for you to accomplish, please contact the
nearest TEAC Factory Service Department or write directly
to a TEAC office, the addresses of which are printed on the
back cover.
This Service Manual is designed to provide up-to-date
information to assist the skilled service technician to prop 
erly repair, adjust and maintain the TEAC A-650 Stereo
Cassette Tape Deck.
The A-650 is a high quality deck designed to be used as an
indispensable part of a superior home stereo system. It
contains a 2-motor transport utilizing a DC reel motor and
a Phase ocked oop (P ) servo motor, push button
control panel, Memory Counter with Play feature, Record
Mute feature, advanced Dolby NR circuitry, Peak indica 
tors, imiter, 3-position BIAS and EQ selector Switches, as
well as many of the standard TEAC features.
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* Noise reduction circuit made under license from Dolby
aboratories Inc. The word “ Dolby ” and the Double-D
symbol are trademarks of Dolby aboratories Inc.

TABLE OF CONTENTS
21
3
1. Test Equipment Required
4
2. Specifications & Service Data
6
3.
Parts ocation
24
6-3-5.
32
33
Block Diagram
16 7.
5-8.
evel Diagram
34
8.
Trouble-Shooting
35
9.
2
5-9.
5-10.
5-11.
5-12.
5-13.
5-14.
19
20
16
16
TEAC Test Tape
ubrication ............................................
Torque Measurement using the Cassette
Torque Meter
Visual Index (for 5-6, 7, 8, 11 Sections)
Voltage and Frequency Setting
Playback Performance
Record/Playback Head Azimuth
Adjustments ................................
Specified Output evel Setting . .
Frequency Response -Playback- . .
Signal to Noise Ratio -Playback- .
5
11
13
15
17
7
7
7
7
8
8
8
9
9
10
10
11
11
4-1.
4-2.
4-3.
4-4.
4-5.
4-6.
4-7.
4-8.
4-9.
4-10.
4-11.
4-12.
6-2.
6-2-1.
25
25
25
26
27
27
28
28
29
29
30
31
6-2-2.
6-2-3.
6-2-4.
6-2-5.
6-2-6.
6-3.
6-3-1.
6-3-2.
6-3-3.
6-3-4.
5-1.
5-2.
5-3.
54.
5-5.
5-5-1.
5-5-2.
5-6.
5-7.
12
12
12
13
13
14
14
14
15
6-4.
6-4-1.
6-4-2.
6-4-3.
6-4-4.
6-4-5.
6-4-6.
6-4-7.
6-4-8.
6-4-9.
. . 21
. . 22
22
. . 23
VU Meter Calibration -Playback- .... 23
Headphone Output evel Checks .... 23
Monitor Performance 24
Minimum Input evel Checks 24
Specified INE Control Setting 24
VU Meter Calibration -Record- 24
ED Peak evel Indicator
Calibration
DO BY NR COPY-OUT-FM
Switch Function Check
Recording Performance
Bias Trap Adjustments
Record Bias Setting
Record evel Setting
Distortion Checks
Frequency Response -Overall- .
Signal to Noise Ratio ■ Overall-
Dolby NR Effect Measurement
Peak imiter Efficiency Checks
Erase Efficiency
6-4-10. Channel Separation
6-4-11. Adjacent Track Crosstalk
Measurement
4. Partial Disassembly of Main Parts
Case/Front.Panel
Tape Transport Chassis Removal . . .
Partial Rotation of Front Chassis . . .
Head
Pinch Roller
Cassette Holder
Capstan Motor
Capstan Drive Ass ’ y/Drive Belt . . . .
Reel Motor .......................................
Brake Plate Ass'y
Reel Tables ........................................
Idler Ass ’ y
5. Mechanical Checks and Adjustments
Take-up Torque .................
Fast Forward & Rewind Torque . . .
Pinch Roller Pressure
Brake Tension
Tape Speed/Wow and Flutter
Tape Speed
Wow and Flutter
Flywheel Bearing Adjustment
CASSETTE IN Switch Position
Adjustment
RECORD SAFETY Switch
Position Adjustment
Cassette Holder Motion Checks ....
Oil Retaining Washer Clearance
Check 16
Eject ock ever Adjustment 17
Pushbutton Control Checks 18
Auto-End Stop Facility Check 19
Memory Device Function Checks .... 19
6. Electrical Checks and Adjustments
6-1. Adjustment ocation

1. TEST EQUIPMENT REQUIRED
Spring scale: 1.
4.
*
Fig. 1-1 Spring Sca e & Cassette Ree Adapter
Fig. 1-2 P astic A ignment Too
Fig. 1-3 E-3 Head Demagnetizer
Fig. 1-4 TZ-261 Tape Recorder C eaner Kit Fig. 1-5 TZ-255 Oi Kit
3
0 — 100 g- cm (0 - 1.4 oz- inch)
0-160 g-cm (0 — 2.2 oz-inch)
5.
6.
7.
8.
9.
2.
3.
TEAC E-3 or equivalent
TEAC TZ-261 Tape Recorder Cleaner kit or pure alcohol
TEAC TZ-255 Oil kit or equivalent
0 - 70 g (0 - 2.5 oz.)
0 - 200 g (0 - 7.0 oz.)
Spring scale:
Wow/flutter meter:
Frequency counter.
AF oscillator:
AC VTVM:
10. Attenuator:
11. Distortion analyzer:
12. Oscilloscope:
13. Band-pass filter:
14. Test load resistor:
15. Plastic alignment tool.
16. Head demagnetizer:
17. Cleaner:
18. Oil
For take-up torque check:
For fast forward & rewind torque checks:
String: ength: about 50 cm (20 ” )
Cassette Reel Adapter: Diameter: 22 mm
* The tools above (1 - 3) are constructed as shown in Fig. 1-1.
Cassette Torque Meter: For take-up torque check:
For fast forward & rewind torque checks:
Use of the Cassette Torque Meter instead of the spring scale, if you have one, is recommended for easier
measuring. (See Fig. 5-3 on page 13.)
When ordering Cassette Torque Meter, allow for longer delivery' time that is required for it.
For Pinch Roller pressure check: 0 - 1 kg (2.2 lbs)
MEGURO DENPA SOKKI K.K., Model MK-668A or D & R Co.. Model F -4B.
Digital type, capable of 10 Hz to 100 kHz indication.
10 Hz - 100 kHz
0.1 mV - 300 V
General Purpose
Basic frequency 400 Hz/1 kHz
General Purpose
1 kHz narrow band-pass type
Non inductive type 8 ohm/1 W

2. SPECIFICATIONS & SERVICE DATA
SPECIFICATONS
or more)
Equalization
Head Configuration
2 Motors
TEAC TEST TAPE
0 dB = DIN Reference level (333 Hz)
REMARKS:
MTT-lli:
MTT-502:
MTT-150:
MTT-116K:
MTT-116U:
14 kHz/ — 24 dB
Fig. 2-1 TEAC Test Tape
4
Track System
2 Heads
Type of Tape
Tape Speed
Inputs
(level and impedance)
Outputs
(level and impedance)
Power Consumption
Weight
Bias Frequency
Operating Position
Power Requirement
For BIAS 1/EQ 1 (CrO 2 )
For BIAS 2/EQ 2 (Fe-Cr)
For BIAS 3/EQ 3 ( ow Noise.
High Output tape)
4-track. 2-channel stereo
Erase and Record/Playback
Cassette tape. C-60 and C-90 (Philips type)
4.8 cm/s (1 -7/8 ips)
Microphones: Min. input level: — 67 dB (345 m V)/(10 kohms
ine: Specified input level: — 9 dB (274 mV)/(50 kohms)
Min. input level: — 19 dB (86 mV)
DIN*: Min. input level: — 35 dB (13.7 mV)
DO BY FM/COPY: FM: -17 dB (109 mV)
COPY: — 9dB(274 mV)
ine out: Max. output level: +1 dB (0.869 V)/(into 50 kohms)
Specified output level: — 5 dB (435 mV)
Headphones: Specified output level: — 15.7 dB (130 mV)/(8 ohms)
EQ 1: 3180 ms + 70 ms (for CrO 2 tape)
EQ 2: 3180 ms + 70 ms (for FcCr tape)
EQ 3: 3180 ps + 120 ms (for regular Hi-Fi tape)
1/2-track. 1 -channel Erase Head
1/4-track. 2-channel Record/Playback Head
1 Phase ocked oop Servo Controlled DC Capstan Motor
1 Mechanical Governed DC Reel Motor
100 kHz
Horizontal
1 00/1 17/220/240 V AC, 50/60 Hz (General Export Models)
117V AC, 60 Hz (USA/Canada Models)
220/240 V AC. 50 Hz (Europe Model)
240 V AC. 50 Hz (Australia Model)
35W
13 kg (28% lbs.) net
For playback performance alignment
• For Dolby level calibration
• Dolby B-type tone (400 Hz tone).
200 nWb/m
• For frequency response test for EQ 1 &
2 (CrO 2 & Fe-Cr)
• 3180 ms + 70 ms
• 315 Hz/ — 4 dB. 31.5 Hz ~ 14 kHz/-24 dB
• For frequency response test for EQ 3
(Hi-Fi tape)
• 3180 ms + 120 ms
•315 Hz/-4dB.3I.5 Hz
For tape speed & wow/flutter test
• For Playback method
•3.000 Hz/- 10 dB
• For Record/Playback method (blank tape)
For record performance alignment (blank tape)
MTT-505B or similar:
MTT-504 or similar:
MTT-501 or similar:
NOTE: The TEAC test tapes require longer delivery time
titan regular parts.
* Pursuant to DIN Standards

SERVICE DATA
F c
o
■1HH
\ ‘ ,: C
©
E
o
Fig. 2-2 A-650 Dimensions
5
330nvn
Erase Efficiency
Channel Separation
Crosstalk Between Adjacent Tracks
Total Harmonic Distortion
Electrical
Frequency Response
Signal to Noise Ratio
Mechanical
Tape Speed Deviation
Tape Speed Drift
Wow and Flutter
Pinch Roller Pressure
Reel Torque
Fast Winding Time
End-stop Activate Time
Refer to frequency response limits charts on page 22 and 28
Playback method: CrO? & Fe-Cr tapes: 48 dB (minimum)
Hi-Fi tape: 46 dB (minimum)
Record/Playback method: CrOj & Fe-Cr tapes: 46 dB (minimum)
Hi-Fi tape: 44 dB (minimum)
With Dolby Noise Reduction used for recording and playback, S/N
ratio is improved by 5 dB at 1 kHz and 10 dB at frequencies over 5 kHz.
65 dB minimum
30 dB minimum (at 1 kHz)
40 dB minimum (at 125 Hz)
BIAS/EQ 1: 2.5% (maximum)
BIAS/EQ 2: 2.5% (maximum)
BIAS/EQ 3: 2.5% (maximum)
440mm
.7-V
T-S93
NOTE: • Improvements may result in Specifications and Service Data changes.
• Value of “ dB ” m tire Data refers to 0 dB = 0.775V, except where specified. If a Test Set or
VTVM calibrated to 0 dB = IV is to be used, appropriate compensation should be made.
3,000 Hz ±30 Hz
15 Hz
Playback: 0.07% (WRMS)
0.15% (RMS)
Record/Playback: 0.18% (WRMS)
400 g +20 g (13.5 ~ 15.0 oz)
Take Up: 40 ~ 70 g-cm (0.6 ~ 1.0 oz-inch)
Fast Forward: 100 ~ 1 50 g-cm (1 .4 ~ 2.1 oz-inch)
Rewind: 100 ~ 150 g em (1.4 ~ 2,1 oz-inch)
90 seconds for C-60
1.5 seconds ±0.5 seconds
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3. PARTS LOCATION
------ RECORD SOLENOID
MUTING PC BD. ------ -----
VU LEVEL METER PC BD.
HEAT SINK
POWER SUPPLY PC BD.
INPUT-OUTPUT PC BD
RECORD/PLAYBACK
amd ; Dr on
POWER TRANSFORMER
I6P CONNECTOR
CONTROL PC BD.
--------- TRAP COIL PC BD
REEL MOTOR
-------- LEVER SWITCH PC BD
HALL EFFECT ELEMENT
FLYWHEEL
I
7-576
Top View Fig. 3-1
SUPPLY REEL TABLE ----- -----
LED PC BD.
VU METERS
POWER SWITCH
MIC JACKS
ERASE HEAD
PHONES JACK
T-575
Front View
Fig. 3-2
6
1
I
DRIVE BELT ------
PAUSE SOLENOID -----
----- TAKE -UP REEL TABLE
CASSETTE
HOLDER
----- CAPSTAN MOTOR SERVO PC BD.
----- CAPSTAN MOTOR
’ i r?
' IB O;0l
J 3 ; f
eiiO
AMPL PC BD
DOLBY B TYPE
PROCESSOR PC BD.
9P CONNECTOR
! 1 ----- OUTPUT CONTROL
! * ----- LINE CONTROL
1 ----- MIC CONTROL
REC/PLAY HEAD -----
PINCH ROLLER ------
BUTTON ASSY -----

4. PARTIAL DISASSEMBLY OF MAIN PARTS
NOTE
3.
I.
4.
2.
4-1. CASE/FRONT PANEL
4-M4x10
3-B M3x6
A
Fig. 4-1
4-2. TAPE TRANSPORT CHASSIS REMOVAL
First do procedure in section 4-1.
I.
2.
3.
4.
4-BSB M3x6
G
First do procedure in section 4-1.
Fig. 4-2 Tape Transport Chassis Remova
7
4-3. PARTIAL ROTATION OF FRONT
CHASSIS
1.
2.
3.
4.
Most removal and replacement can be made with the Front
Chassis section (E) tilted in the forward direction, as ex 
plained in the preceding section .without removing tape
transport chassis (A) which is held in place by screws (F).
Disconnect the 16P Plug and the 9P plug. See Fig. 3-1
on page 6.
Unscrew the screws (B) (H) (C) (F) in that order and
loosen (D) to facilitate next step.
Tilt the Front Chassis section (E) forward and away
from the main chassis (G).
ift the tape transport chassis (A) from the main
chassis.
Use the proper tools. Demagnetize tire tools
before use.
When mounting or removing a spring, pay heed
to the position (direction) of the anchor or hook.
The wrong position may result in a change in the
tension.
BSB M3x6i
. '^ b
• 3-BSB M3x6
Case/Front Panel Removal
BSB M3x6'
c — r'
4-BSB M3x6<-
When reassembling, don ’ t forget to reinstall all
hardware such as springs and washers, etc.
For assembling hardware shape identification,
see ASSEMB ING HARDWARE CODING IST
in the Parts ist.
NOTE
When removing or installing the Front Panel, center
the levers of tire toggle switches on the Front Panel
to make the work easier.
4 E
D
Remove the parts in the following sequence.
Top Cabinet Ass ’ y (D)
Cassette Holder Cover Ass ’ y (A)
To remove the Cassette Holder Cover, do the following:
a. Depress EJECT lever.
b. Move the latch arm protruding from the top of tire
Cassette Holder Door to the left to release tire
Cover.
c. Allow the Cover to rotate outward on its hinge;
then lift up gently on the Cover to remove it from
the Door.
Knobs (C)
Front Panel Ass ’ y (B)
BSB M3x6
c>
, / B'SB,M3x3

4-4. HEAD
First do procedure in section 4-1.
1.
ERASE HEAD
O ’
2.
Fig. 4-3 Heads/Pinch Roller Replacement
4-5. PINCH ROLLER
First do procedure in section 4-1.
1.
REC/PLAY
ERASE
2.
T-463
Fig. 4-4 Head Wiring Diagram
A
4-6. CASSETTE HOLDER
First do procedures in section 4-1 and 4-2.
2-PSA M2.6x6
2-BSA M3x6
5.
6.
2-BSA M3x6
Fig. 4-5 Cassette Ho der Remova
8
Unsolder each lead wire from the terminal pins of tire
head to facilitate replacement. To re-solder each head
wire to the newly replaced head, refer to Fig. 44.
2. ift up the heads after taking off tire hardware mount 
ing them.
1.
2.
Remove the E-ring retaining the Pinch Roller Ass ’ y (A)
and remove the Spring (B) from the hook (C) of the
Head Base Plate and the tab of the Pinch Roller Ass ’ y.
Remove the Pinch Roller Ass ’ y from the pivot stud pin
of the Plate.
Take off the 2 screws (H) from the transport chassis.
oosen the 2 screw (G) to separate the Cassette Holder
Door (F) and the Cassette Holder (E).
Detach the Door (F) from the chassis.
Remove the Micro Switch Ass ’ y (B) to simplify the
next steps.
Take off the E-ring (A) to separate the Cassette Holder
(E) from the chassis.
Remove the Holder (E).
RED
WHT
GRN
BLU
3.
4.
NOTE
After replacement, always clean the driving surfaces
of the Pinch Roller with the TEAC TZ-261B Rubber
Cleaner or with pure alcohol, then proceed directly
to the PINCH RO ER PRESSURE adjustment
section. See page 13.
NOTE
1. After replacing the head, always adjust the head
alignment, especially the Record/Playback Head ’ s
azimuth (see 6-2-1), and then secure the screws
and/or the nut with a drop of locking paint.
Connect the wires to the head terminal pins
quickly to prevent breaking of internal wires of
the head due to overheating.
W-20
N - M *£vr'L
J©
O SW-20
B M2x4
2-B M2x4
O ’
REC/PLAY HEAD
.^W-20 '

4-7. CAPSTAN MOTOR
3.
B.
1.
3-BSA M3x6"
2.
Viewed from Rear
3.
Fig. 4-6 Capstan Motor Replacement
4.
4-8. CAPSTAN DRIVE ASS'Y/DRIVE BELT
First do procedures in section 4-1 and 4-3.
1.
2.
3-B M2.6x6x-
3.
Viewed from Rear
4.
5.
Fig. 4-7 Capstan Drive Ass ’ y/Drive Belt Replacements
6.
1.
1.
2.
2.
I. „
3.
4.
3.
9
Release the Drive Belt from the Motor Pulley.
oosen the two screws holding the P.C. Board insula 
tor, remove the insulator and then unsolder the wires
marked with asterisks (*) from tire PC Board (part of
tire Motor Ass ’ y). Note the color code and the position
of each wire prior to unsoldering the leads.
Remove the Motor Ass ’ y together with the PC Board
from the chassis by taking off the screws.
Remove the Control PC Board Ass ’ y (1) bj' taking off
tire 4 screws (J).
Detach the Flywheel Bearing Plate Ass ’ y (C) from the
mounting studs by unscrewing the 4 screws (H).
Take out the Drive Belt (E) from the Motor Pulley (B)
and the Flywheel (F).
Pull apart the Oil Retaining Washer (A) from the shaft
of the Flywheel.
Carefully lift out the Flywheel from the Capstan Hous 
ing Ass ’ y (C).
Remove the Capstan Housing Ass ’ y from the chassis
by unscrewing the 3 screws (D).
1.
2.
NOTE
Since the Capstan Drive Ass ’ y is a precision part,
TEAC specially distributes the Flywheel and the
Capstan Housing Ass ’ y as a whole assembly.
Hence, always replace the Flywheel together
with the Capstan Housing Ass ’ y.
Clean all driving surfaces of the Flywheel and the
Drive Belt with TEAC TZ-261 Cleaner kit ( “ A ”
for Flywheel. “ B ” for Belt) or with pure alcohol.
Do not bend the Capstan Shaft as this will in 
crease wow/flutter or speed deviation.
During re-assembly re-attach the Drive Belt with 
out twisting or stretching it.
z
4-B M3x6
First remove tire Top Cabinet Ass ’ y (see 4-1), then do
section 4-3.
UBRICATION:
For lubrication of the newly replaced Capstan Drive Ass ’ y,
the following should be observed.
Apply a drop of a light machine oil of good quality
(e.g.: TEAC TZ-255) with an oil applicator to the shaft
of the Flywheel and spread oil evenly over the shaft
with a flannel cloth. After installing the Flywheel, be
sure to clean the tape moving portion of shaft with
TEAC TZ-261 A Head Cleaner or with pure alcohol.
Apply a drop of the proper oil in the same way as
above to the innermost area of capstan shaft (next to
the Flywheel).
Apply a film of light grease to the well of the Flywheel
Bearing Plate (K).
NOTE
When re-assembling, clean the pulley and the Belt
with TEAC TZ-261 Cleaner kit ( “ A ” for the
Pulley. “ B ” for the Belt) or with pure alcohol.
Take off or remount the Motor Ass ’ y taking care
not to scratch or otherwise damage the Motor
Pulley.
When re-attaching the Drive Belt to the Pulley do
not twist or stretch the belt.
When remounting the PC Board be sure to install
the mica insulator between the transistor and the
PC Board mounting bracket.

4-9. REEL MOTOR
First do procedures in section 4-1,4-3 and 4-8.
1.
2.
-E
D
3.
4.
5.
H
6.
Viewed from Rear
Ree Motor Rep acement
Fig. 4-8
4-10. BRAKE PLATE ASS ’ Y
First do procedures in section 4-1,4-3,4-8 and 4-9.
1.
4.
Viewed from Rear
Fig. 4-9 Brake P ate Ass'y Remova
10
Remove the Spring (G) by unhooking each end from
the spring fastener on the chassis and the spring hook
on the Plate (F) respectively.
Detach the Plate (F) by unscrewing the 2 screws.
Remove parts (E) (D) (B) (A: Brake Plate Ass ’ y) illus 
trated all the way in that sequence.
Remove each Brake Shoe (C) from the Brake Plate
Ass ’ y .
2.
3.
NOTE
When remounting the Fast Wind Idler Ass ’ y (B), clean
the driving surface of the Idler with the TEAC TZ-
261 B Rubber Cleaner or with pure alcohol.
3-PSA
M2.6x6
O ’
| F
n
gf) E-2.5
sb
Remove whole Reel Motor Ass ’ y (J) from the mount 
ing studs by taking off the 3 screws.
Detach only the Motor body (1) by unscrewing the 3
screws from the Motor Base Plate Ass ’ y (H).
To further disassemble other parts illustrated in the
box area, do the following steps.
Take off the screw (A), then separate tire Fast Wind
Idler Ass ’ y (B) from the Plate Ass ’ y (H). Pay special
attention not to lose the Steel Ball (C).
Remove the Fast Wind Arm Plate (D) from the Plate
Ass ’ y .
Disconnect the Spring (G) from the spring hook of the
Tension Arm Ass ’ y (E), remove tire ‘ E ’ ring (F), then
lift off the Tension Arm Ass ’ y.
1 G ».
J
2-BSA
M3x6
A X JX... J
psa n /WY)
M2.6x8 U
S ’ I
jJ B2-PSA M
- t ^g'*M2.6x4 V'
I T 3-PSA
2.6x4 <^-
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