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1
7.1.12 PROTECTION CIRCUIT
If the TIMER LED on the front panel flashes, check the protection circuit.
SIDE A
Note: If the protection circuit activates, the unit will not recover for 60 seconds even if the AC power cord is disconnected then reconnected.
If you activate Service Test mode, the protection circuit becomes invalid, which makes diagnosis easy. (To activate Service Test mode,
A
A
while holding the STOP key and the DISC 1 key pressed, press the STANDBY/ON key.)
DVDM ASSY (HTD540 /KUC)
There are three types of operations for the protection circuit, which are indicated on the FL display when Service Test mode is entered:
PRTCT WNG: The unit was shut down because of an abnormality in the AMP system. (The PROTECT line operates at the MID level.)
PRTCT ERR: The unit was shut down because of a failure in the AMP system. (The PROTECT line operates at the LO level.)
30
DVD PRTECT: The unit was shut down because of a failure in the DVD system. (The VDET line operates at the HI or LO level.)
30
A
Conditions for the protect circuit operations
Q451
Voltage
D431
HI level
C443
B
PROTECT
MID level
C431
LO level
7
7
HI level
1
1
VDET
MID level
IC431
R401
C432
LO level
C404
The possible failures for each error message are as follows:
IC441
PRTCT WNG:
C442
R443
• The Speaker terminal became overloaded because of short-circuit. (See 1.)
R442
R441
PRTCT ERR:
• The main power supply became LO level because of short-circuit or disconnection of connectors. (See 2.)
• Disconnection of the FAN connector or interruption of rotation of the fan (See 3.)
C
• DC was generated at the output because of a failure in the AMP system, etc. (See 4.)
• Abnormal temperature was detected by the thermistor. (See 5.)
DVD PRTECT:
• An error was generated in the main power supply inside the DVDM. (See 6.)
Protection circuit that activates against a PRTCT WNG error
1 When the Speaker terminal becomes overloaded
C413
C414
C412
R3601
R3607
1.8k
0
A
D
B
Front L ch
Q3601
R3603
33k
C424
D3601
C425
GND FL
D3603
DAP202K
F
R485
C805
In Normal mode, the speaker (6 ohms) is connected between the
C806
E
R481
R811
FL and GND FL points. Because the voltage at Point A is higher
C481
7
7
than that at Point B, Q3601 does not operate.
1
1
C483
If the resistance between the FL and GND FL points becomes
1.83 ohms or less, Q3601 begins to operate, Q3639 is turned on,
Q3640 (E, C, and B)is turned on, and the level of XPROTECT
R482
becomes MID.
→ The microcomputer detects the XPROTECT level and
H
shuts the power to the unit off.
F
112
1
2
A1
4
A3
4
1
12
12
CN901
1
A2
4
CN921
R983
R981
Q951
R451
TRAY POS
6
7
R982
SEDR+
6
R921
>3.55V
Normal
R918
SEDR-
C902
6
1
7
1.8V - 3.5V
The unit is shut down because of an abnormality.
Q925
8
CN124
Q926
<1.8V
5
The unit is shut down because of a failure.
CN124
5
8
14
>4.25V
The unit is shut down because of a failure.
C901
4
R908
R909
4
R196
3.3V
Normal
R199
<2.5V
The unit is shut down because of an abnormality.
C403
C434
D927
C401
R409
R408
A
A
SPDL_PDM
C491
R403
C405
Q401
C410
Q930
R938
R939
D
R462
B
C307
C641
R620
C462
C311
C312
C642
C318
C315
C634
R693
C694
C681
R697
C415
104
ROT_DRV
7
C621
R673
D
D
C
AF Assy
6CH AMP Assy
C622
IC604
VD+5
R108
X601
27k
3
1
R626
C422
C636
+5V
to
4
IC691
156
5
C691
157
XPROTECT
IC601
157
C692
C661
R3639
R5559
L691
C671
R698
27k
270k
CN607
Q3640
1
1
C
2
2
Q3639
R883
B
C601
+
CN608
D601
C3633
1
E
1
23
23
10/50
R839
2
24
24
R805
2
C827
IC806
1
3
R804
5
4
C807
R814
5
5
C825
38
1
R817
4
4
R818
R895
C482
R819
65
R820
102
IC801
C813
R823
C830
R838
R837
R836
C803
C816
C801
C802
C815
2
3
B
CN101
1
1
CN104
CN105
1
4
4
1
CN122
CONTACT
1
SIDE
17
1
17
R102
C114
C118
CN122
Conditions
C120
C116
R101
7
CLAMP
R191
C101
IC101
21
R194
1
7
DISCSENS
1
7
OPEN
Q192
22
1
2
C132
1
2
CN123
C302
C306
B
IC301
25
CN123
C326
26
FG
2
Q921
IC301
Q927
C
3
Q928
50
51
51
R361
R937
R367
C301
R936
R332
C303
R333
C354
R354
C308
R334
L361
R363
R658
R341
C652
R336
R398
C
R337
R397
R339
R340
R696
C346
C664
53
52
C650
R638
R639
C647
R637
R648
R634
R647
C637
C630
R629
R635
C623
R628
R683
R682
R681
1
C604
R619
208
R672
208
C698
C684
29
R617
R603
R602
R616
E
R686
30
R889
C828
IC601
30
R890
R893
R888
R848
8
8
5
5
1
4
1
4
R886
R835
R825
R824
C873
R868
C860
R884
R869
R833
R832
R843
R831
R844
C809
R878
R830
R829
XV-HTD540
3
4
C
24
1
24
1
2
24
23
1
CN121
CN121
FL display in Service Test mode
IC101
PRTCT WNG
R220
R221
R222
IC201
PRTCT ERR
C222
GNDD
R223
LD2
LD1
DVD PRTECT
R202
Q390
R212
R390
R391
C394
C392
DVD PRTECT
R310
R301
RFOUT
1
C201
RFIN
C300
C391
1
R302
C383
100
R396
C211
NP
R969
C388
C382
C377
R384
R383
75
R382
75
CN301
C373
10
2
SY
GNDD
V
9
1
GNDD
SC
GNDD
Cr/R
C305
GNDD
Cb/B
Q722
GNDD
R368
CY/G
R309
R308
R721
RGB
P/XI
C362
C357
ASPECT
R362
R595
R594
R593
S_Y
12
R590
R562
V
8
C1564
S_C
13
Cr
11
C561
Cb
10
D761
Y
9
Q782
Q781
R775
Q742
R760
R770
CONTACT
SIDE
Q741
D
C797
C798
R774
LETTER
C795
C774
SQUEEZE
VSEL2
R773
VSEL1
C773
R789
GNDA
R794
R737
SR
C794
C758
R738
R793
GNDA
R859
C877
C793
SL
R758
GNDA
C756
LFE
R757
GNDA
C755
C
GNDA
FR
GNDA
C874
1 FL
G
R858
C850
C851
C871
4
SIDE A
30
20
Front Side
- Quick Links:
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Troubleshooting
