Uher 24 hi fi Special Service Manual

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22 Hi-Fi Special
24 Hi-Fi Special

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22 Hi-Fi Special
24 Hi-Fi Special

l/003/865

Contents
Page
1. Transport Mechanism ......................... l
2. Clutches ................................ 1
2.1 Checking the Clutches .................. 2
2.2 Adjusting the Heighht of the Clutches ........... 2
2.3 Checking and Adjusting the Clutch in the Drive Wheel . . . 2
2,31 Checking the take-up Pull of the right-hand Clutch ..... 2
2,82 Checking and Adjusting the Pressure between the
Drive Wheel and the Lower Section of the Clutch ..... 2
3. Brakes ................................ 3
3.1 Checking and Adjusting the Clutch Brakes ......... 3
3.2V Checking and Adjusting the Brakes of the Braking Discs . . 3
4. Tape Feed ............................... 3
4.1 Measuring the Feed Pull 3
4.2 Adjusting the Pressure of the Pressure Roller
against the Capstan .................... 4
5. Tape Tension Control ......................... 4
5.1 Checking the Tape Tension Control ............ 4
5.2 Adjusting the Height of the Tape Tension Control ..... 4
6. Electrical Pause Control ........................ 5
6.1 Testing .......................... 5
6.2 Adjustment ........................ 5
7. Fast Forward and Rewind Operation ................. 5
8. Speed Selector ............................ 6
8,1 Testing .......................... 6
8.2 Adjusting the Friction Wheel ................ 6
83 Changing the Friction Wheel ............... 6
8.4 Equalization Selector ................... 6
9. Automatic Tape Stop .......................... 7
9.1 Testing .......................... 7
9.2 Adjusting ......................... 7
10- Tape Guides .............................. 7
11. Sound Heads ............................. 7-8
12. Lubrication and Servicing ....................... 8
12.1 Lubrication ........................ 8
12.2 Servicing ......................... 8

The proper performance of service operations on UHER tape recorders requires the
following items in addition to the usual workshop equipment:

vacuum tube voltmeter UHEFl alignment tape
audio-frequency oscillator UHER test tape

oscilloscope circlip pliers

wow and flutter meter Spring balance, range 1,0009
demagnetizer spring balance, range 50 g

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1. Transport Mechanism (see Fig- I)

The motor pulley (A) of the hysteresis-synchronous-motor (B) drives via friction wheel (C) the
flywheel (D) and, accordingly, the capstan (E). The tape is pressed by pressure roller (F) against
the rotating capstan (E) and is thus moved. The tape speed is selected by adjusting the friction

wheel (C), which engages the motor pulley (A) at various steps. The appropriate equalization is'

selected along with the tape speed. The force required for winding the tape is produced by the
motor pulley (A) via belt (G) and the left-hand friction wheel (H). the right-hand friction wheel (I),
belt (K), and the drive wheel (L) drives the lower section (M) of the right»hand clutch. The lower
section (N) of the left-hand clutch is driven, when the recorder is switched to REWIND, via friction
wheel (H), which in turn is driven by the motor pulley (A) and the belt (G). When the recorder is
switched to FAST FORWARD, the lower section (M) of the right-hand clutch is driven by the friction
wheel (H), which is in turn driven by friction wheel (I). The digital counter (O) is driven by the right-
hand clutch via the belt (P).

Fig. l
2. Clutches
The constructional design of the left-hand and right-hand clutches is shown in Fig. 2.
A-Turntable
B - Lower clutch section A
C - Flat spring
D - Metal washer
F - Braking disk
V C
G - Rubber washer _ _ D
H - Plastic inset . E
l- Retaining screw _ L :2'--- F
K - Washer -*-'- fl
L - Height adjusting wedge g E I
The turntable(A) of the left-hand clutch embodies - K
L

an additional weight. Fig. 2 @-

22 Hi-Fi Special
24Hi-Fi Special