Mitsubishi Electric CITY MULTI PQRY-P200YMF-B Service Handbook page 126

Checking
Meaning, detecting method
code
6602 Transmission processor hardware
error
6603 Transmission circuit bus-busy er-
ror
1. Collision of data transmission:
Transmission can not be per-
formed for 4~10 consecutive
minutes due to collision of data
transmission.
2. Data can not be transmitted on
transmission line due to noise
for 4~10 consecutive minutes.
Note:
The address/attribute
shown on remote
controller indicates the
controller which has
detected error.
Cause
Checking method and processing
Transmission line
installed while turning
power source on?
NO
Check power source of indoor
unit.
220V ~ 240V?
YES
Check transmission line
work and shield finish
Ground fault or shield
contacted with transmission
line?
NO
System composition?
Single refrigerant
Plural refrigerant
system
system
Confirm supply power connector
CN40 of heat source unit
YES
Modification of CN40
insertion method.
Investigation of trans- * For the investigation method, follow <Investiga-
mission line noise tion method of transmission wave shape/noise>
YES
Noise exist?
NO
Faulty controller of
generating unit
1) As the voltage of short frequency like
noise is mixed in transmission line
continuously, transmission processor
can not transmit.
2) Faulty controller of generating unit.
–123–
Checking method & Countermeasure
YES
Shut off the power source of heat source/
indoor units/BC controller and make it again.
NO
Erroneous power
source work
YES
Erroneous transmis-
sion work
NO
Only 1 set with
CN40 inserted?
Investigation of the
cause of noise
a) Check transmission wave shape/noise on trans-
mission line by following <Investigation method
of transmission wave shape/noise>.
→ No noise indicates faulty controller of generat-
ing unit.
→ Noise if existed, check the noise.
MELANS connected
system
Confirm supply power connector
CN40 of heat source unit
CN40 inserted?
YES
Replace insertion
of CN40 to CN41
Modification of
faulty point