SLV-777HF, SLV-778HF, SLV-788HF - Sony VCR Service Manual (repair manual). Page 7

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See below for note.

1)

Remove screw 1 (+P3 

×

 8) and remove the ground shaft

assembly 2. (Refer to Fig. 4.)

2)

Remove soldering which is marked by arrow and remove the
rotary upper drum board completely.

3)

Remove two screws 3 (PSW3 

×

 8) and remove the rotary

upper drum in the direction of A. (Refer to Fig. 5.)
If removal is difficult, remove it while rotating it slowly.

Note:

If removal is difficult, check again if soldering is removed
completely.

Fig. 4

1)

Pay attention so that finger print or like must not be put when
inserting a new upper drum into lower drum.

2)

Align  mark of the rotary upper drum board with the  mark of
the rotary transformer board so that the screw hole on the upper
drum and that on the lower drum are aligned. (Refer to Fig. 5.)

3)

If attaching is difficult, attach a upper drum while rotating it
slowly.

Note:

Pay attention not to damage the video heads.
Confirm that the upper drum is inserted completely.

4)

Tighten the two screws 3 (PSW3 

×

 8). (Refer to Fig. 5.)

5)

Fix the earth shaft 2 by tightening the screw 1 (+P3 

×

 8) so

that protrusion at the tip of the earth shaft contacts the center
of the drum shaft.

Note:

When attaching the ground shaft assembly 2, never give

force to the plate spring 4.

Fig. 5

1

 Screw (+P3 

×

 8)

2

 Ground shaft assembly

Drum when viewed 
from the top

Soldering

4

 Plate 

     spring

Soldering

3

 PSW3 

×

 8

Upper drum assembly
DZR-45-R (8-848-576-02) 
                 (777HF, 778HF)

Align the two arrow marks.

A

Lower drum assembly 
DZL-51B/J-RP (8-848-666-11)

                       (777HF, 778HF)

It cannot be divided to two parts, the
upper and the lower drum assemblies.

NOTE : There are two types of drum assembly built in models except SLV-788HF (DZH-94A/Z-RP only).

There are two printed circuit boards 
on the top.

UPPER DRUM ASSEMBLY

DZR-45-R 

(777HF, 778HF)

(8-848-576-02)

There is no printed circuit board.

DRUM ASSEMBLY

DZH-94A/Z-RP

(8-839-044-02)