Mitsubishi Electronics P500YMF-C Phenomena, Unit is removed, Main board ----CNS1, CNVCC3

Phenomena Factors

4“HO” indication on 1) The M-NET transmission power supply form the

the remote controller	outdoor unit is not supplied.
is not lit, and the	1	The original power supply of Indoor Unit is not
ON/OFF switch does		turned on.
not work.	2	The connector on the controller board in Indoor
		Unit is removed.
		Main board ----CNS1, CNVCC3
		INV board----CNAC2, CNVCC1, CNL2

3Power supply circuit defects of the outdoor unit. (For detail, refer to Pages 127)

●INV board defects

●Diode stack defects

●Prevention resistance of rush current (R1) damage.

2)Short circuit of the M-NET transmission line

3)Error wiring of the M-NET transmission line on the side of the outdoor unit

1 A break of the transmission line or terminal block removal

2 Indoor Unit transmission line is wired to the transmission line terminal block (TB7) for the central control by mistake.

4)M-NET transmission line break on the side of Indoor

Unit (Short/ Open)	In the case of 2), 3) and 7)
5) Loose or disconnection of wiring between the M-NET	factors, indicate 7102 errors
	by the self-diagnosis LED of
transmission terminal block (TB 5) of Indoor Unit and
	the outdoor unit.
Indoor Unit controller board CN2M and disconnection of
connectors

6)Error wiring of the MA remote control

1 Short circuit of the MA remote wiring

2 A break of the MA remote control line (No.2) and

disconnection of the terminal block connection

3 Reversed wiring, cross-over in the group control 4 Wire by mistakes the MA remote control to the terminal block (TB5) for the transmission line

5 Connect by mistakes the M-NET transmission line to the MA remote control terminal block (TB13)

7)The unit address is not “00” as it should be with automatic address setting.

8)The address of Indoor Unit becomes 51 or more.

9)The master and slave setting of the MA remote control becomes the slave setting.

10)Use the M-NET remote control in spite of the automatic address.

11)Defects for the room controller board (MA remote communication circuits)

12)Defects for the remote controller

Check method and handling

The same		NO
phenomena in all unit of the same
refrigerant system happen?
				Check for the terminal
YES				block (TB15) voltage
				for the transmission
Self-diagnosis LED				line of the indoor unit
checks				NO
			Check for 4) item
				19 ~ 12V?
				YES
7120 error display?		YES	Check for 2) and 3) of	Check the items of
			factors	5), 6), 8), 9), and 10)
NO			Modify the defective	YES
			places	Factors available?
Check for 11) item				NO
			Modify the defective
				Defects of the indoor
			places
				unit controller board or
				MA remote control
Factors	YES		Change the M-NET
			remote control to the
available?
			MA remote control.
NO
Check for 1) item			Modify the defective
			places

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