Yamaha Portatone PSR-550 Service Manual page 12

PSR-550
11. Keyboard Assembly
(Time required : About 10 min.)
11-1. Remove the lower case assembly. (See procedure 1)
11-2. Remove the two (2) screws marked [440B]. The
keyboard assembly can then be removed. (Fig. 4)
12. Speakers
(Time required : About 10 min.)
12-1. Remove the lower case assembly. (See procedure 1)
12-2. Remove the right and left (woofer) speakers by
removing four (4) screws marked [L30] from each
speaker. (Fig. 4)
12-3. Remove the right and left (tweeter) speakers by
removing two (2) screws marked [420H] from each
speaker. (Fig. 4)
13. LCD and Back Light Assembly
(Time required : About 20 min.)
13-1. Remove the lower case assembly. (See procedure 1)
13-2. Remove the DM circuit board and the shield box
U and L. (See procedure 3)
13-3. Remove the floppy disk drive assembly.
(See procedure 4)
13-4. Remove the AM circuit board. (See procedure 5)
13-5. Remove the PN 1/5 circuit board. (See procedure 6)
13-6. The LCD can then be removed with the back light
assembly. (Fig. 9)
Back Light Assembly
14. Disassembling the Keyboard Assembly
14-1 Remove the keyboard assembly. (See procedure 11.)
14-2 Remove the two (2) screws marked [30]. The
MKS5 circuit board can then be removed. (Fig. 4)
14-3 Remove the MK-L and MK-H circuit boards while
pressing the fifteen (15) hooks A inward, and then
remove the rubber contact. (Fig. 10)
14-4 Remove the twenty-one (21) screws marked [140],
then remove the black keys from the lower notes.
Afterwards, remove the white keys DFA and C'
and then remove the white keys CEGB from the
higher notes. At this time, lift the keys from the
front and slide them towards you. the keys can then
be removed from the assembly. (Fig. 11)
Hooks A
Black Key
Rubber Contact
12
LCD Rubber Connector
(Fig.9)
MK-L , MK-H
White Key
(Fig.10)
Black Key
White Key
DFA
White Key
CEGB
[140] : Bind Head Tapping Screw-P
(Fig.11)
15. Assembling the Keyboard Assembly
15-1 Install the white keys CEGB from the lower notes,
and then install the DFA keys and C' key.
Afterwards install the black keys from the higher
notes, and tighten the twenty-one (21) screws
marked [140]. (Fig. 11)
15-2 Install the rubber contacts in the assembly while
pressing the keys as shown in Figure 12. Check
that the rubber contact has been firmly placed into
position in the area indicated by the arrow in Figure 13.
When fitting the rubber contacts, raise both ends
of the frame so that keys do not push the rubber
contact up.
15-3 Install the MK-L and MK-H circuit boards in the
assembly so that the hooks B hold it as shown in
Figure 14.
Rubber Contact
(Fig.12)
(Fig.13)
MK-L , MK-H
(Fig.14)
[140]
[140]
Black Key
White Key C'
3.0X16 MFZN2Y (EP600310)
Rubber Contact
Hooks B