Hitachi RAS-EH36PHLAE Service Manual page 72

0 f-<f+----l--+!+-+-,o+.1f-+----,t-+---+<l-l
10. Indoor/outdoor communication circuits
Indoor transmission circuit
Indoor microcomputer {IC601}
Indoor transmission output
Indoor reception input Indoor unit reception circuit
< Typical communication waveform>
"
Microcomputer
�
transmission signal
Microcomputer
rece tion si nal
Signal between F cables 1 and 2
Microcomputer
-1'l
·;;; transmission signal
Microcomputer
rece tion si nal
0
< Enlarged waveform >
Signal sent by indoor microcomputer
; r-t+-+-t+-t-+-++-t-tl--1---1---t+-i
ov f-''+--+-'-t-'-+-''+''-+--,,-+--+''-+
Sms. /DIV
• Indoor and outdoor communications are conducted by using lines 2 and 3 of F cable. Line 2 of F cable is shared with a
transmission channel that powers the outdoor unit.
• Data communicated between the indoor and outdoor units are outputted from the microcomputer as serial signals and are
transmitted as demodulated by a 30 kHz carrier wave. (Both the indoor and outdoor microcomputers directly output a signal
demodulated at 30 kHz.)
OV
I
Indoor unit side
12V
C302 T
'jlOV
T he unit is receiving a signal that it sent
(it is not used particularly as a signal).
G)
®
0
@
G)
0
Signal sent by outdoor microcomputer
ov
Sms. /DIV
"' t-+--+---++-+--+--+---<-+--+---t
:':, f-<ttttltt>---fftlt-ttttlflfff--+-IIIH--ttt
OY �IIIII-III--IIIII-IIIIIIIIN---1--11111--111-
I I
I I
Outdoor unit side
i i
! !
1
1
Fig.10-1
@ Signal between F cables 1 and 2
30 kHz demodulated waveform
Sms./DIV
Fig. 10-2
72
12V
;'.; 1-+++--+---++-t--<l+-l'-+--+-+-+-++---l
C
Inverter circuit
Outdoor
microcomputer
Outdoor
reception
input
Signals sent by indoor and outdoor
microcomputers (I)G)
G)
:':, >-+++--+---Ho-+-+>+-+--+-1-11--++---I
ov �-....P..--+-'--1----1-1--+-'-+>-4---I
Sms./DIV