Harman JBL SUB 550P, Service Manual, Page: 13 / 43

Sub550P/230 Troubleshooting flow chart
yes
Stand-by BD check
+6V,-6V, Stand-by
VOL.
no
no yes
yes
no
yes
no
yes
no
yes
no
yes no
yes
no
no
yes
yes
no
.
Start
Dc voltage check
±Vcc,±15V
OK
Check transformer
C
168,
C
169
,D
123
,
D
124,
C
170
Power on check
LED red &blue
OK
Check vol module
& connector
cable& ±15V.ect
Check THD output
power, noise
OK
Check pre board
& power board ,
±Vcc,±15V ect
Test frequency
Response
OK
Check U
102
,R
124
,
C
104,
R
125
,C
117
.ect
Test input sensitivity
OK
Check U
101
,R
117,
R
112,
R
114
ect
Test protection
OK
Check U
107
.R
237
±15Vcc ect
Test limiter circuit
OK
Check U
106
.Q
107
ect
Auto off Function
Hi pot test
OK
Check U
103
.Q
101.
Q
102
.C
131.
R
142
;Ac
cord, Transformer.
OK
Listening test
OK
The Amp ass’y ok
END
Test phase sw,low
pass sw rabos vr
Check sw103,102,
R158,163,177 ect
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