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Service Manual
BRIDGEABLE FOUR-CHANNEL POWER AMPLIFIER

BRIDGEABLE 4-CH POWER AMPLIFIER
FUSE 25A

ORDER NO.

25

GM-X374/XR/UC

CRT3007

GM-X374

XR/UC,XR/EW,XR/ES

For details, refer to "Important symbols for good services".

PIONEER CORPORATION

4-1, Meguro 1-Chome, Meguro-ku, Tokyo 153-8654, Japan PIONEER ELECTRONICS (USA) INC. P.O.Box 1760, Long Beach, CA 90801-1760 U.S.A. PIONEER EUROPE NV Haven 1087 Keetberglaan 1, 9120 Melsele, Belgium PIONEER ELECTRONICS ASIACENTRE PTE.LTD. 253 Alexandra Road, #04-01, Singapore 159936

C PIONEER CORPORATION 2002

K-ZZY. NOV. 2002 Printed in Japan

1

2

3

4

SAFETY INFORMATION
A

- GM-X374/XR/UC
CAUTION This service manual is intended for qualified service technicians; it is not meant for the casual do-it-yourselfer. Qualified technicians have the necessary test equipment and tools, and have been trained to properly and safely repair complex products such as those covered by this manual. Improperly performed repairs can adversely affect the safety and reliability of the product and may void the warranty. If you are not qualified to perform the repair of this product properly and safely, you should not risk trying to do so and refer the repair to a qualified service technician. WARNING

B

This product contains lead in solder and certain electrical parts contain chemicals which are known to the state of California to cause cancer, birth defects or other reproductive harm. Health & Safety Code Section 25249.6 - Proposition 65

[ Important symbols for good services ]
In this manual, the symbols shown-below indicate that adjustments, settings or cleaning should be made securely. When you find the procedures bearing any of the symbols, be sure to fulfill them:
C

1. Product safety
You should conform to the regulations governing the product (safety, radio and noise, and other regulations), and should keep the safety during servicing by following the safety instructions described in this manual.

2. Adjustments
To keep the original performances of the product, optimum adjustments or specification confirmation is indispensable. In accordance with the procedures or instructions described in this manual, adjustments should be performed.

D

3. Cleaning
For optical pickups, tape-deck heads, lenses and mirrors used in projection monitors, and other parts requiring cleaning, proper cleaning should be performed to restore their performances.

4. Shipping mode and shipping screws
To protect the product from damages or failures that may be caused during transit, the shipping mode should be set or the shipping screws should be installed before shipping out in accordance with this manual, if necessary.

5. Lubricants, glues, and replacement parts
E

Appropriately applying grease or glue can maintain the product performances. But improper lubrication or applying glue may lead to failures or troubles in the product. By following the instructions in this manual, be sure to apply the prescribed grease or glue to proper portions by the appropriate amount.For replacement parts or tools, the prescribed ones should be used.

F

2 1 2

GM-X374/XR/UC

3

4

5

6

7

8

CONTENTS
SAFETY INFORMATION ............................................2 1. SPECIFICATIONS........................................................3 2. EXPLODED VIEWS AND PARTS LIST .......................4 2.1 PACKING...............................................................4 2.2 EXTERIOR .............................................................6 3. SCHEMATIC DIAGRAM .............................................8 3.1 OVERALL CONNECTION DIAGRAM(GUIDE PAGE) ....8 4. PCB CONNECTION DIAGRAM ................................14 4.1 AMP UNIT...........................................................14 5. ELECTRICAL PARTS LIST ........................................18 6. ADJUSTMENT..........................................................20 7. GENERAL INFORMATION .......................................21 7.1 DIAGNOSIS ........................................................21 7.1.1 DISASSEMBLY .........................................21 7.1.2 CONNECTOR FUNCTION DESCRIPTION .......22 7.2 IC ........................................................................23 8. OPERATIONS............................................................24
A

B

C

1. SPECIFICATIONS
Power source .............................................................................................................. 14.4 V DC (10.8 -- 15.1 V allowable) Grounding system ............................................................................................................................................ Negative type Current consumption ........................................................................................................ 19.2 A (at continuous power, 4 ) Backup current ................................................................................................................................................. 3.0 mA or less Average current drawn* .......................................................................................................... 6.7 A (4 for four channels) 10.9 A (4 for two channels) Fuse .................................................................................................................................................................................. 30 A Dimensions ........................................................................................................................ 265 (W) × 50 (H) × 237 (D) mm [10-1/2 (W) × 2 (H) × 9-3/8 (D) in] Weight ........................................................................................................ 2.8 kg (6.2 lbs) (Leads for wiring not included) Maximum power output ...................................................................................................................... 70 W × 4 / 200 W × 2 Continuous power output .......................................................... 35 W × 4 (at 14.4 V, 4 , 20 -- 20,000 Hz, 0.08% THD) 100 W × 2 (at 14.4 V, 4 , 20 -- 20,000 Hz, 0.8% THD) 50 W × 4 (at 14.4 V, 2 , 20 -- 20,000 Hz, 0.8% THD) Load impedance ............................................................................................................................ 4 (2 -- 8 allowable) (Bridge connection: 4 -- 8 allowable) Frequency response ............................................................................................................ 10 -- 45,000 Hz (+0 dB, ­1 dB) Signal-to-noise ratio ...................................................................................................................... 100 dB (IHF­A network) Distortion ............................................................................................................................................ 0.008% (10 W, 1 kHz) Separation ........................................................................................................................................................ 65 dB (1 kHz) Low pass filter ................................................................................................................................ Cut off frequency: 80 Hz Cut off slope: ­12 dB/oct High pass filter .............................................................................................................................. Cut off frequency: 80 Hz Cut off slope: ­12 dB/oct Maximum input level/impedance .................................................................................... RCA: 6.5 V/22 k (0.2 -- 6.5 V) Speaker: 26 V/40 k (0.8 -- 26 V)

D

E

Note:
· Specifications and the design are subject to possible modification without notice due to improvements.

*Average current drawn
· The average current drawn is nearly the maximum current drawn by this unit when an audio signal is input. Use this value when working out total current drawn by multiple power amplifiers. F

GM-X374/XR/UC

3 7 8

5

6

1

2

3

4

2. EXPLODED VIEWS AND PARTS LIST
2.1 PACKING
A

B

C

D

E

F

4 1 2

GM-X374/XR/UC

3

4

5

6

7

8

NOTE:
- Parts marked by "*" are generally unavailable because they are not in our Master Spare Parts List. - Screws adjacent to mark on the product are used for disassembly. - For the applying amount of lubricants or glue, follow the instructions in this manual. ( In the case of no amount instructions, apply as you think it appropriate.)
A

- PACKING SECTION PARTS LIST
Mark No. Description 1 2 3 4 5 6 7 8 9 10 Cord Screw Assy Screw Polyethylene Bag Cover Polyethylene Bag Carton Contain Box Protector Owner's Manual(UC) Part No. HDE0044 HEA0058 BYC40P180FZK HEG0011 HNS0101
B

HEG0013 HHG0354 HHL0354 HHP0169 HRD0219 HRD0221 HRD0224 HRD0225 HRY1157
C

*

Owner's Manual(EW) Owner's Manual(ES) 11 Owner's Manual(ES) 12 Warranty Card

- Owner's Manual Part No. Language HRD0219 English, French HRD0221 English, French, Spanish, German, Italian, Dutch HRD0224 English, Spanish HRD0225 Portuguese(B), Arabic

D

E

F

GM-X374/XR/UC

5 7 8

5

6

1

2

3

4

2.2 EXTERIOR

A

B

C

D

E

F

6 1 2

GM-X374/XR/UC

3

4

5

6

7

8

- EXTERIOR SECTION PARTS LIST
Mark No. Description 1 2 3 4 5 6 7 8 9 10 Screw Screw Chassis Panel Panel Case Spacer Spacer Heat Sink Amp Unit(UC) Part No. BBZ30P060FZK BBZ30P160FZK HNA0014 HNB0188 HNB0193 HNB0195 HNM0006 HNM0124 HNR0232 HWH0208 HWH0209 HWH0210 BBZ30P050FZK BBZ30P080FMC CKF1059 HEK0030 HKB0020 HKB0021 HKE0048 HKE0052 HKM1077 HKM1077 HNC0054 HNC0082 HNC0145 HNR0233 PPZ30P100FZK HXA0391 ISS30P055FUC PPZ30P100FZK HBA0029 STP60NF06FP 2SD2395 2SB1566 FML22R FML22S HNM6623 HBA0030 BBZ30P060FZK
B A

Amp Unit(EW) Amp Unit(ES) 11 Screw 12 Screw 13 Terminal(CN604) 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Fuse(30A) Pin Jack(CN802) Pin Jack(CN801) Terminal(CN601) Terminal(CN851) Connector(CN803) Connector(CN804) Clip Holder Clip Heat Sink Screw Light Pipe Unit Screw Screw Screw FET(Q612,613,614,615) Transistor(Q660) Transistor(Q661) Diode(D611) Diode(D612) Cushion Screw Screw

C

D

E

F

GM-X374/XR/UC

7 7 8

5

6

1

2

3

4

3. SCHEMATIC DIAGRAM
3.1 OVERALL CONNECTION DIAGRAM(GUIDE PAGE)
A
A-a A-b

Large size SCH diagram

A AMP UNIT

A-a
GAIN = 1

A-a

A-b

Guide page

A-a

A-b

Detailed page

B

GAIN = -12dB
INPUT SELECT

C

D

GAIN = 1
UC ONLY

EW, ES ONLY

BEADS CORE (EW, ES ONLY)

E

E

75µH

75µH EW, ES ONLY

UC ONLY

BEADS CORE (EW, ES ONLY)

F

8

A
1 2

GM-X374/XR/UC

3

4

5

6

7

8

A-b
A
AMPLIFIER GAIN = 5.2 - 35.4dB
HPF/LPF SELECT

10k(A)

B

10k(A)

C
HPF/LPF SELECT

10k(A)

D
10k(A)

*** UC EW, ES R608 1R3K 6R2K R609 1R3K 6R2K

EW, ES ONLY *** EW, ES ONLY *** 50µH BFC
RM4Z-LFJ4

E
FU602 HEK0030 30A

>

UC ONLY

NOTE : Symbol indicates a resistor. No differentiation is made between chip resistors and discrete resistors. Symbol indicates a capacitor. No differentiation is made between chip capacitors and discrete capacitors. The > mark found on some component parts indicates the importance of the safety factor of the part. Therefore, when replacing, be sure to use parts of identical designation.

Decimal points for resistor and capacitor fixed values are expressed as : 2.2 2R2 0.022 R022

F

GM-X374/XR/UC

5

6

7

A 8

9

D

C

E

B

A

F

A-a A-b

10
GAIN = 1

A-a
INPUT SELECT

1

1

A AMP UNIT
HPF/LPF SELECT

1

2

2

GM-X374/XR/UC

2

3

3

GAIN = -12dB

3

4

4
HPF/LPF S

5

5

4

GAIN = 1
UC ONLY

6

6

5

EW, ES ONLY BEADS CORE (EW, ES ONLY)

EW, ES ONLY

GM-X374/XR/UC
75µH 75µH EW, ES ONLY BEADS CORE (EW, ES ONLY) UC ONLY

BFC

7

7

6

A-a
A-a A-b
D C E B A

8

8

11

F

D

C

E

B

A

F

A-a A-b

12
AMPLIFIER GAIN = 5.2 - 35.4dB

A-b

1

1

/LPF SELECT

1

2

2

10k(A)

GM-X374/XR/UC

10k(A)

2

3

3

3

4

4

HPF/LPF SELECT

10k(A)

5

UC ONLY

RM4Z-LFJ4

5
*** UC EW, ES R608 1R3K 6R2K R609 1R3K 6R2K *** EW, ES ONLY *** 50µH FU602 HEK0030 30A

10k(A)

4
6

6
NOTE : Symbol indicates a resistor. No differentiation is made between chip resistors and discrete resistors. Symbol indicates a capacitor. No differentiation is made between chip capacitors and discrete capacitors. The > mark found on some component parts indicates the importance of the safety factor of the part. Therefore, when replacing, be sure to use parts of identical designation.

5
>
7

GM-X374/XR/UC

7
Decimal points for resistor and capacitor fixed values are expressed as : 2.2 2R2 0.022 R022

6

A-b
E

8

8

13 B D C

A-a A-b
A

F

1

2

3

4

4. PCB CONNECTION DIAGRAM
4.1 AMP UNIT
NOTE FOR PCB DIAGRAMS A
1.The parts mounted on this PCB include all necessary parts for several destination. For further information for respective destinations, be sure to check with the schematic diagram. 2.Viewpoint of PCB diagrams

A

AMP UNIT

Connector

Capacitor

SIDE A

B

P.C.Board

Chip Part

SIDE B

SPEAKER INPUT
1 AL+ 4 2 AR- AR+ AL3

INPUT SELECT

C

OUTPUT
R+ L+ R- L-

R+ R-

L+ LL+ L-

D
R+ R-

INPUT
1 BL- BL+ 4 2 BR- BR+ 3

E

SPEAKER INPUT LPF/HPF SELECT

F

A
14

A 1

GM-X374/XR/UC

2

3

4

5

6

7

8

SIDE A
A

B

FU602

1

C

2

3

POWER SUPPLY

D

5

1

6

2

7

3

E
8 4

SPEAKER OUTPUT

BFC
F

GM-X374/XR/UC

A A
7 8

15

5

6

1

2

3

4

A
A

AMP UNIT

B

1

C

D

1

E

F

A
16

A
1 2

GM-X374/XR/UC

3

4

5

6

7

8

SIDE B
A

B

1

C

L-

L-

D

L-

1

E

A
GM-X374/XR/UC

F

5

6

7

A 8

17

1

2

3

4

5. ELECTRICAL PARTS LIST
A

NOTES: - Parts whose parts numbers are omitted are subject to being not supplied. - The part numbers shown below indicate chip components. Chip Resistor RS1/_S___J,RS1/__S___J Chip Capacitor (except for CQS.....) CKS....., CCS....., CSZS.....
=====Circuit Symbol and No.===Part Name --- ----------------------------------------------Part No. ------------------------=====Circuit Symbol and No.===Part Name --- ----------------------------------------------L L L L L L L T T TH S S S S VR VR FU 601 602 603 801 802 851 852 601 601 603 101 151 601 801 301 351 602 Choke Coil 50µH (EW, ES) Choke Coil 75µH (EW, ES) Choke Coil 75µH (EW, ES) Ferri-Inductor Ferri-Inductor Ferri-Inductor Ferri-Inductor Transformer (UC) Transformer (EW, ES) Thermistor Switch(HPF/LPF SELECT) Switch(HPF/LPF SELECT) Switch(BFC) (EW, ES) Switch(INPUT SELECT) Volume 10k(A) Volume 10k(A) Fuse 30A Beads Core (EW, ES) Part No. ------------------------HTH0005 HTH0010 HTH0010 CTF1007 CTF1007 CTF1007 CTF1007 HTT0019 HTT0025 HCX0001 HSH0005 HSH0005 HSH-156 CSH1042 CCS1265 CCS1265 HEK0030 HTF0001

B

A Unit Number
Unit Name
MISCELLANEOUS
IC IC IC IC IC IC IC IC IC IC IC IC IC IC Q Q Q Q Q Q 101 102 151 152 501 502 551 552 601 602 801 802 851 852 201 202 601 602 603 604 606 607 608 609 612 613 614 615 660 661 905 906 907 201 601 603 604 611 612 613 614 615 616 909 911 IC IC IC IC IC IC IC IC IC IC IC IC IC IC Transistor Transistor Transistor Transistor Transistor Transistor Transistor Transistor Transistor Transistor FET FET FET FET Transistor Transistor Transistor Transistor Transistor Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode LED

: : : :

HWH0208 (UC) HWH0209 (EW) HWH0210 (ES) Amp Unit
NJM2068D NJM2068D NJM2068D NJM2068D TDA7294V TDA7294V TDA7294V TDA7294V PA2027A UPC494C NJM2068D NJM2068D NJM2068D NJM2068D KSR2202 KSC1623 KSC1623 KSA812 2SB1243 KSR2202 2SD1919 2SD1919 2SB1277 2SB1277 STP60NF06FP STP60NF06FP STP60NF06FP STP60NF06FP 2SD2395 2SB1566 KSA812 KSC1623 KSC1623 1SS133 RM4Z-LFJ4 HZS7L(B2) 1SS133 FML22R FML22S HZS16L(1) HZS16L(1) ERA15-02VH ERA15-02VH 1SS133 L934BR235SRCF

C

RESISTORS
R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R 101 102 103 104 121 122 123 124 151 152 153 154 171 172 173 174 201 202 203 204 205 206 301 302 303 304 351 352 353 354 501 502 503 504 505 RS1/16S912J RS1/16S912J RS1/16S103J RS1/16S103J RS1/16S123J RS1/16S123J RS1/16S223J RS1/16S223J RS1/16S912J RS1/16S912J RS1/16S103J RS1/16S103J RS1/16S123J RS1/16S123J RS1/16S223J RS1/16S223J RS1/16S472J RD1/4PU102J RD1/4PU202J RD1/4PU223J RD1/4PU103J RD1/4PU333J RS1/16S222J RS1/16S222J RS1/16S470J RS1/16S470J RS1/16S222J RS1/16S222J RS1/16S470J RS1/16S470J RS1/16S223J RS1/16S223J RS1/16S561J RS1/16S561J RD1/4PU473J

D

Q Q Q Q Q Q Q Q Q Q Q Q Q D D D D D D D D D D D D

E

F

18 1 2

GM-X374/XR/UC

3

4

5

6

7

8

=====Circuit Symbol and No.===Part Name --- ----------------------------------------------R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R 506 507 508 509 510 551 552 553 554 555 556 557 558 559 560 601 602 603 604 605 606 607 608 608 609 609 610 611 612 613 614 616 619 620 621 622 623 625 626 627 628 631 632 635 636 637 638 641 642 643 645 646 647 648 649 654 655 656 665 666 801 802 803 804 805 (EW, ES)

Part No. ------------------------RD1/4PU473J RS1/2PMF100J RS1/2PMF100J RD1/4PU473J RD1/4PU473J RS1/16S223J RS1/16S223J RS1/16S561J RS1/16S561J RD1/4PU473J RD1/4PU473J RS1/2PMF100J RS1/2PMF100J RD1/4PU473J RD1/4PU473J RD1/4PU102J RD1/4PU473J RD1/4PU103J RD1/4PU103J RD1/4PU222J RD1/4PU472J RD1/4PU472J RD1/4PU132J RD1/4PU622J RD1/4PU132J RD1/4PU622J RD1/4PU103J RD1/4PU472J RD1/4PU101J RD1/4PU221J RD1/4PU152J RS1/16S101J RS1/16S102J RS1/16S473J RS1/16S102J RS1/16S153J RD1/4PU105J RD1/4PU332J RD1/4PU332J RS1/16S472J RS1/16S472J RD1/4PU272J RS1/16S472J RS1/2PMF121J RS1/2PMF121J RS1/2PMF121J RS1/2PMF121J RD1/4PU472J RD1/4PU472J RS1/2PMF220J RD1/4PU472J RD1/4PU472J RS1/2PMF100J RS1/2PMF100J RS1/2PMF220J RD1/4PU223J RD1/4PU223J RD1/4PU223J RS1/2PMF220J RS1/2PMF220J RS1/16S471J RS1/16S471J RS1/16S223J RS1/16S223J RN1/10SE1002D

=====Circuit Symbol and No.===Part Name --- ----------------------------------------------R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R 806 807 808 811 812 813 814 831 832 833 834 851 852 853 854 855 856 857 858 861 862 863 864 917 918 919 920 924 930 931

Part No. ------------------------RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RS1/16S753J RS1/16S753J RS1/16S753J RS1/16S753J RS1/16S471J RS1/16S471J RS1/16S223J RS1/16S223J RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RN1/10SE1002D RD1/4PU104J RD1/4PU472J RD1/4PU103J RD1/4PU392J RD1/4PU473J RD1/4PU331J RD1/4PU331J

A

B

(UC) (EW, ES) (UC) (EW, ES)

C

CAPACITORS
C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C 101 102 103 104 121 122 123 124 151 152 153 154 171 172 173 174 201 202 501 502 503 504 505 506 507 508 509 510 537 538 539 540 551 552 553 CFTNA274J50 CFTNA274J50 CFTNA154J50 CFTNA154J50 CFTNA124J50 CFTNA124J50 CFTNA124J50 CFTNA124J50 CFTNA274J50 CFTNA274J50 CFTNA154J50 CFTNA154J50 CFTNA124J50 CFTNA124J50 CFTNA124J50 CFTNA124J50 CEAT100M16 CEAT100M16 CEAT220M50 CEAT220M50 CEAT101M50 CEAT101M50 CEAT220M50 CEAT220M50 CFTNA104J50 CFTNA104J50 CFTNA104J50 CFTNA104J50 CFTNA333J50 CFTNA333J50 CQMA102J50 CQMA102J50 CEAT220M50 CEAT220M50 CEAT101M50

D

E

F

GM-X374/XR/UC

19 7 8

5

6

1

2

3

4

=====Circuit Symbol and No.===Part Name --- ----------------------------------------------C C C C C C C C C C C C C C C 554 555 556 557 558 559 560 567 568 569 570 601 602 603 606 607 608 609 611 612 613 614 615 616 617 618 619 620 621 622 623 624 631 632 633 634 635 636 637 638 3300µF/16V 3300µF/16V

Part No. ------------------------CEAT101M50 CEAT220M50 CEAT220M50 CFTNA104J50 CFTNA104J50 CFTNA104J50 CFTNA104J50 CFTNA333J50 CFTNA333J50 CQMA102J50 CQMA102J50 CFTNA103J50 CFTNA224J50 CFTNA103J50 CFTNA103J50 CEAT100M16 CEAT100M16 CEAT470M16 CEAT220M50 HCH0013 CFTNA103J50 CFTNA103J50 CEAT100M16 CEAT221M10 CQMA102J50 CEAT2R2M50 CEAT101M16 CQMA472J50 CQMA472J50 CQMA102J50 HCH0005 HCH0005 CEAT470M16 CEAT470M16 CEAT221M35 CEAT221M35 CEAT470M16 CEAT470M16 CFTNA473J50 CFTNA473J50

=====Circuit Symbol and No.===Part Name --- ----------------------------------------------C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C 644 651 652 653 654 670 801 802 803 804 805 806 807 808 809 810 811 812 831 832 833 834 851 852 853 854 855 856 857 858 859 860 861 862 901 2200µF/35V 2200µF/35V 2200µF/35V 2200µF/35V

Part No. ------------------------CQMA102J50 HCH0010 HCH0010 HCH0010 HCH0010 CQMA103J50 CCSRCH471J50 CCSRCH471J50 CEAT100M16 CEAT100M16 CQMA472J50 CQMA472J50 CCSRCH470J50 CCSRCH470J50 CCSRCH470J50 CCSRCH470J50 CFTNA103J50 CFTNA103J50 CEAT100M16 CEAT100M16 CEAT100M16 CEAT100M16 CCSRCH471J50 CCSRCH471J50 CEAT100M16 CEAT100M16 CQMA472J50 CQMA472J50 CCSRCH470J50 CCSRCH470J50 CCSRCH470J50 CCSRCH470J50 CFTNA103J50 CFTNA103J50 HCH0012

A

B

C C C C C C C C C C C C C C C C C C C C C C C C C

470µF/16V

C

220µF/10V

D

6. ADJUSTMENT
There is no information to be shown in this chapter.

E

F

20 1 2

GM-X374/XR/UC

3

4

5

6

7

8

7. GENERAL INFORMATION
7.1 DIAGNOSIS 7.1.1 DISASSEMBLY
- Removing the Case (not shown) 1. Remove the eight screws and then remove the Case.
A

- Removing the Amp Unit (Fig.1)

Panel
1 1 1 1
B

1 2 3 4

Remove the eight screws.

Remove the two screws and then remove the two Panels. Remove the eight screws and then remove the two Heat Sinks.

4
Remove the five screws and then remove the Amp Unit.

4 3 3
C

3 3 4

3 3

3

4

4

3
D

1 2 1 2

1 1

Heat Sink

Amp Unit

Panel

Heat Sink
Fig.1

E

F

GM-X374/XR/UC

21 7 8

5

6

1

2

3

4

7.1.2 CONNECTOR FUNCTION DESCRIPTION
A

- GM-X374/XR/UC

6.5V

0.2V

6.5V

0.2V

B

C

BRIDGEABLE 4-CH POWER AMPLIFIER
FUSE 30A

30 D

E

F

22 1 2

GM-X374/XR/UC

3

4

5

6

7

8

7.2 IC
*TDA7294V
A

7 2

13 14

3

4 10 9

B
6

MUTE STBY
1 8

THERMAL SHUTDOWN
15

S/C PROTECTION

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15
C

NON INVERTING INPUT

STAND-BY GND

+Vs (SIGNAL)

INVERTING INPUT

+Vs (POWER)

BOOTSTRAP

-Vs (SIGNAL)

-Vs (POWER)

NC

STAND-BY

NC

MUTE

OUT

SUR

NC

D

IC's marked by * are MOS type. Be careful in handling them because they are very liable to be damaged by electrostatic induction.

E

F

GM-X374/XR/UC

23 7 8

5

6

D

C

E

B

A

F

24

8. OPERATIONS

1

1

Gain Control
The power indicator lights when the power is switched on.

Power Indicator

Adjusting the gain controls A and B will help match the output of the car stereo to the Pioneer amplifier. Normally, set the gain controls to the "NORMAL" position. If the output is low, even when the volume of the car stereo is turned up, turn these controls clockwise. If there is distortion when the volume of the car stereo is turned up, turn these controls counter-clockwise.

BFC (Beat Frequency Control) Switch
2
If you hear a beat while listening to an MW/LW broadcast with your car stereo, change the BFC switch using a small standard tip screwdriver.

2
LPF/HPF Select Switch
LPF (Left) OFF (Center) HPF (Right)

· If you only use one input plug, set the gain controls for speaker outputs A and B to the same position. · When using with an RCA equipped car stereo (standard output of 500 mV), set to the NORMAL position. When using with an RCA equipped Pioneer car stereo with max. output of 4 V or more, adjust level to match the car stereo output level. · If you hear too much noise when using the speaker input terminals, turn the gain control counter-clockwise.

GM-X374/XR/EW GM-X374/XR/ES

GM-X374/XR/UC

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3

LPF (Low-Pass Filter)/HPF (High-Pass Filter) Select Switch
Set the LPF/HPF select switch as follows according to the type of speaker that is connected to the speaker output connector and the car stereo system: Audio frequency range to be output
Very Low Frequency range Full range Low Frequency range to High Frequency range

Input Select Switch
Speaker Type
Subwoofer Full range Full range

For two-channel input, slide this switch to the left. For four-channel input, slide this switch to the right.

Remarks
Connect a subwoofer.

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4

Use if you want to cut the very low frequency range because it is not necessary for the speakers you are using.

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Connection Diagram
A

Ground wire (black) [RD-223] (sold separately) Connect to metal body or chassis. Fuse (30 A) Special red battery wire [RD-223] (sold separately) After making all other connections at the amplifier, connect the battery wire terminal of the amplifier to the positive (+) terminal of the battery. Fuse (30 A)
B

Grommet Connecting wires with RCA pin plugs (sold separately).

RCA input

Amplifier with RCA input jacks

External Output If only one input plug is used, do not connect anything to RCA input jack B.

Car stereo with RCA output jacks

C

Front side

Speaker input terminal

RCA output jack

RCA input jack B RCA input jack A

D

Back side Speaker output terminal See the "Connecting the Speaker wires" section for speaker connection instructions. Fuse (30 A) × 1

Connecting wires with RCA pin plugs (sold separately).

E

System remote control wire (sold separately) Connect the male terminal of this wire to the system remote control terminal of the car stereo (SYSTEM REMOTE CONTROL). The female terminal can be connected to the auto-antenna relay control terminal. If the car stereo does not have a system remote control terminal, connect the male terminal to the power terminal through the ignition switch.

F

GM-X374/XR/UC

25 7 8

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