Toshiba MMY-MAP0804HT8-E Service Manual page 247

(8) Set Bits 1 and 2 of SW30 on the interface P.C. board same as that of the failed header unit (terminator
resistance setting).
Outdoor interface P.C. board of unit selected as new header unit
1 2 3 4
1 2 3 4
1 2 3 4
[Wiring changes to communication line]
(9) Redirect the indoor-outdoor communication line connected to the failed header unit [U1/U2] to the unit selected
as the header unit [U1/U2].
(10)If a central control device is connected, connect the central control communication line [U3/U4] to the
communication line terminal of the unit selected as the new header unit [U3/U4], and connect up the tie
connector between the [U1/U2] and [U3/U4] terminals.
(11)Turn on the power supply to all the units connected to the system other than the failed unit.
Determine what to do with the power supply to the failed unit in the following manner.
<In case of fault in compressor, electrical part, I/F P.C. board, or IPDU P.C. board>
Leave the power supply off.
<In case of fault in refrigerating circuit or related part (pressure sensor, temperature sensor, refrigerating cycle
part, or fan system part)>
Turn on the power supply to protect the compressor (by turning on the case heater).
(When the power supply to the unit is turned on, [E19] (error in the number of outdoor header units) will be
displayed on the 7-segment display. However, this will not cause any problems.)
This is the end of header outdoor unit backup operation setting. Check the operation.
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(7)
Turn on Bit 2 of SW09.
SW06 SW07 SW09
1 2 3 4 1 2 3 4
SW11 SW12 SW13
1 2 3 4 1 2 3 4
SW16 SW17
Set SW13 and SW14
identically to failed header unit.
1 2 3 4
Failed header unit
Outdoor-outdoor communication line (U5/U6)
(9)
Redirect the indoor-outdoor communication
line from failed header unit to unit selected
as header unit [U1/U2].
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SW10
1 2 3 4
SW14
1 2 3 4
Set Bits 1 and 2 of SW30
(6)
identically to failed header unit.
Unit selected as new header unit
(previously follower unit No. 1)
Central control communication line
(U3/U4 terminal)
Outdoor-outdoor communication line
(U1/U2 terminal)
If central control device is connected, redirect central
control communication line from failed header unit to
unit selected as new header unit [U3/U4].
246
(8)
Follower unit No. 2
(10)