Revox A77 Service Manual

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Once adjustments are made on the headblock, the loosened
screws must be resecured with lacquer.
Note:
For improved signal to noise performance the connections
to both playback head channels may be reversed on some
recorders from the wiring shown in Diag. 3, in other words
the colored conductors will be soldered to the right-hand
terminal. When replacing heads, re- wire in the same manner.
4.2. Tape Tension
Cover light at the optical end- of- tape switch.
Measurement values are taken on a core of diameter
115 mm ( 4,5 " ).
Load and lock empty reel.
— Wind several turns of thread on empty reel and pull
thread off slowly in the sense indicated, resulting in
the following values:
A
Fig. 4.2-21
I 4.5" I
Function 7.5 ips or 3.75 ips
A
B
PLAY
tape tension, high
70 gr
( 2.5 oz.av)
85 gr
(3 oz.av)
PLAY
tape tension, low
30 jr
( 1 oz.av )
50 gr
I 1.75 oz.av I
<<
210 gr
( 7.4 oz.av )
about 20 gr
( . 7 oz.av )
>>
about 20 gr
( . 7 oz.av )
230 gr
( 8.1 oz.av )
Table 4.2-22
Fig. 4.3-24
Check operating voltages of reel motors and phase shift
capacitors if these values aren't attained; see table 5.9 — 46
and section " Modifications " per 8.1.( Rewind ).
4.3. Brakes ( Stop /
The stop brakes are effective with solenoid de- energized.
— Push STOP button.
4.3.1. Brake Torque Measurement
Preparation for measurement per 4.2.
Correctly set brakes have following torques:
60 - 90 g
(2.1 - 3.2 oz.av)
( 4.5" ) ( 4.5")
140 - 175 g I_
I 5 - 6.2 oz.av I — — — — —
Fig. 4.3-23
60 - 90 g
I 2.1 - 3.2 oz.av
140 - 175 g
(5 - 6.2 oz.av)
4.3.2. Brake Adjustment
Check brake system if above mentioned torques are not
reached. Brake linings and bands must be absolutely clean
and free of grease. Brake bands must be devoid of kinks and
lay up full- width on lining.
Details on the modified brake system ( brake return spring
attached to both ends of the brake- band) are shown on
page PL 7a of the parts list. Brake mechanism and solenoid
stroke are reset after exchanging band and/or linings.
Brake Adjustment ( Brake Adj Lever )
Solenoid Adjustment
13

Revox A77 Specifications

General

Brand	Revox
Model	A77
Category	Tape Deck
Language	English