Mitsubishi Electronics MSH-24NV, MSH-07NV, MSH-12NV, MSH-09NV, MSH-18NV service manual

E How to check mis-wiring and serial signal error (when outdoor unit does not work)

MSH-24NV

Start

1. Turn OFF power supply.

❈ 1 Short circuit of JPG and JPS on the

2. Turn ON power supply.

indoor electronic control P.C. board enables self-check to be displayed in 3

Repair wiring.

3. Press EMERGENCY OPERATION switch.

seconds.

Serial signal error is indicated.

3 min. later, what self-check result is displayed on OPERATION (0.5-sec.ON,2.5-sec.OFF)INDICATOR lamp on indoor unit? ❈ 1

Mis-wiring is indicated.(0.5-sec.ON, 0.5-sec.OFF)

Yes

Is there in-out mis-wiring, poor contact, or wire disconnection?

No

1.Turn OFF power supply and disconnect in-out connecting wire on indoor side.

2.Short-circuit between indoor terminal block N and 3

3.Turn ON power supply and press EMERGENCY OPERATION switch.

3 minutes later,is there DC 20V between both ends	No
of R132?
( By tester, the stylus is between 0 ~ 20V. )

Yes

•Turn OFF power supply.

•Connect ON in-out connecting wire. •Turn ON power supply.

No

Is there AC220~240V between outdoor terminal blocks		2 - N ?
	Yes	No
3 minutes later, when EMERGENCY OPERATION
switch is pressed is there DC 5V between J8 + -J7 –
on outdoor DEICER P.C. board?

Yes

3 minutes later, when EMERGENCY OPERATION

switch is pressed and 52C relay turns on, is there No DC 10V between both ends of R601?

(By tester, the stylus is between 5 ~10V)

Yes

Replace the indoor electronic control P.C. board.

Replace in-out connecting wire of 2 and N .

Check and rectify fuse and varistor on out- door DEICER P.C. board.

Replace 3 in-out connecting wire.

Replace the outdoor DEICER P.C. board.

54