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C. Board Exchange Procedures; Replacement Of Indoor P.c. Boards - Toshiba MMU-AP0074YH-E Service Manual

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7
P.C. Board Exchange Procedures
Indoor unit

7-1. Replacement of indoor P.C. boards

Part code
MMU-AP 4MH series
MMU-AP 4SH series
431-6V-437
MMC-AP 4H series
MMD-AP 4SPH series
431-6V-438
MMD-AP 4BH series
MMU-AP 4YH series
MMD-AP 4H series
431-6V-444
MMF-AP 4H series
MML-AP 4BH series
431-6V-469
MML-AP 4H series
Points to note when replacing indoor P.C. board assembly
The electrically erasable programmable read-only memory (hereinafter EEPROM, IC10) mounted on an indoor
P.C. board holds important setting data, including the type and capacity codes intrinsic to the model (set at the
factory), as well as the line / indoor / group addresses, high ceiling adjustment setting and the like (during
installation, either automatically or manually). Proceed with the replacement of an indoor P.C. board assembly in
accordance with the procedure described below.
After completion of the work, check the settings again, including the indoor unit No. and group header / follower
designation, and confirm the integrity of the refrigerating cycle by conducting a test operation, etc.
<Replacement procedure>
Method 1
If it is possible to turn on the indoor unit and read the setting data from the P.C. board to be replaced via a wired
remote controller -
Reading EEPROM data: Procedure 1
Replacing P.C. board and turning on power: Procedure 2
Writing EEPROM data in new EEPROM: Procedure 3
Resetting power supply (applicable to all indoor units connected to remote controller in case of group operation)
Model type
98
P.C. board type
MCC-1402
MCC-1402
MCC-1403
MCC-1403

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