Yamaha Portatone PSR-550 Service Manual page 11

6. PN 4/5 Circuit Board
(Time required : About 15 min.)
6-1. Remove the lower case assembly. (See procedure 1)
6-2. Remove the DM circuit board and the shild box U
and L. (See procedure 3)
[420D]
[420] : Bind Head Tapping Screw-P
7. PN 1/5 Circuit Board
(Time required : About 20 min.)
7-1. Remove the lower case assembly. (See procedure 1)
7-2. Remove the DM circuit board and the shield box
U and L. (See procedure 3)
7-3. Remove the floppy disk drive assembly. (See
procedure 4)
7-4. Remove the AM circuit board. (See procedure 5)
7-5. Remove the PN 4/5 circuit board. (See procedure 6)
7-6. Remove the twenty-five (25) screws marked
[420D]. The PN 1/5 circuit board can then be
removed. (Fig. 6)
8. PN 2/5 Circuit Board
(Time required : About 15 min.)
8-1. Remove the lower case assembly. (See procedure 1)
8-2. Remove the DM circuit board and the shield box
U and L. (See procedure 3)
8-3. Remove the AM circuit board. (See procedure 5)
8-4. Remove the encoder knob from the control panel
side. (Fig. 8)
8-5. Remove the three (3) screws marked [420E]. The
PN 2/5 circuit board can then be removed. (Fig. 6)
[420D]
[420E] [420D]
PN 2/5
3.0X8
6-3. Remove the AM circuit board. (See procedure 5)
6-4. Remove the volume knob from the control panel
side. (Fig. 7)
6-5. Remove the three (3) screws marked [420C]. The
PN 4/5 circuit board can then be removed. (Fig. 6)
[420D]
PN 1/5
PN 4/5
[420D]
[420C] [420D]
Wheel Assembly
MFZN2Y (EP600280)
(Fig.6)
9. PN 3/5 Circuit Board
(Time required : About 5 min.)
9-1. Remove the lower case assembly. (See procedure 1)
9-2. Remove the two (2) screws marked [420F]. The
PN 3/5 circuit board can then be removed with the
wheel assembly. (Fig. 6)
10. PN 5/5 Circuit Board
(Time required : About 5 min.)
10-1. Remove the lower case assembly. (See procedure 1)
10-2. Remove the two (2) screws marked [420G]. The
PN 5/5 circuit board can then be removed. (Fig. 6)
[420G]
PN 5/5
PN 5/5
PN 3/5
[420F]
Volume Knob
(Fig.7)
Encoder Knob
(Fig.8)
PSR-550
11