Adcom GFP-710 User manual

SERVICE MANUAL
STEREO
PREAMPLIFIER
GFP-710
TABLE OF CONTENTS
Introduction ................1
Parts List..................2
Voltage Conversion . . . . . . . . . . . 6
Specifications...............7
Chassis Layout . . . . . . . . . . . . . . .
PCB Layout . . . . . . . . . . . . . . . . .
Wiring Diagram . . . . . . . . . . . . . .
Schematic ............ . ....
10 Timber Lane
Marlboro, NJ 07746
USA
Tel: [phone]
Fax: [phone]
Web: http://www.adcom.com
INTRODUCTION

1
This service manual is intended to assist trained and qualified technical personnel in verifying the
performance of, adjusting, and repairing the ADCOM GFP-710 preamplifier. The procedures described
here are not intended for persons unfamiliar with the appropriate safety and test procedures.
GFP-710 SERVICE PARTS LIST
WARNING
THERE ARE POTENTIALLY LETHAL VOLTAGES WITHIN THE GFP-710 PREAMPLIFIER WHICH
WILL BE ACCESSIBLE ONCE ITS TOP COVER IS REMOVED. DO NOT ATTEMPT
FAMILIARIZATION, INSPECTION, OR ANY PROCEDURE WHATSOEVER UNLESS YOU HAVE
DISCONNECTED THE GFP-710 FROM THE WALL AC OUTLET OR OTHER SOURCE OF AC
POWER AND THE POWER-SUPPLY CAPACITORS ARE COMPLETELY DISCHARGED. THESE
INSTRUCTIONS ARE PROVIDED FOR USE ONLY BY COMPETENT TECHNICAL PERSONNEL. DO
NOT UNDERTAKE ANY SERVICE PROCEDURES IN THE GFP-710 UNLESS YOU ARE
TECHNICALLY QUALIFIED TO DO SO.

2
MAIN PCB AF78115
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
JK101 22001400 4P GOLD RCA JACK
JK105 22001400 4P GOLD RCA JACK
JK102-104 22001090 4P RCA JACK
DN101 22001050 5P DIN JACK
VR135001030 Balance Pot
VR3,VR4 35001010 Bass, Treble Pot
C903,C904 12002230 Capacitor Ceramic 0.01uF 500V
C918 12002230 Capacitor Ceramic 0.01uF 500V
C101 12002010 Capacitor Ceramic 0.047uF 50V
C103 12002010 Capacitor Ceramic 0.047uF 50V
C108,C109 12002010 Capacitor Ceramic 0.047uF 50V
C111 12002010 Capacitor Ceramic 0.047uF 50V
C106,C107 12002150 Capacitor Ceramic 22pF 50V
C301,C302 12005240 Capacitor Elec .33uF 50V
C911 12005010 Capacitor Elec 1000uF 25V
C914,C915 12005010 Capacitor Elec 1000uF 25V
C901 12005070 Capacitor Elec 1000uF 35V
C110 12005020 Capacitor Elec 100uF 25V
C104,C105 12005100 Capacitor Elec 10uF 50V
C112 12005100 Capacitor Elec 10uF 50V
C205,C206 12005030 Capacitor Elec 2200uF 16V
C217,C218 12005050 Capacitor Elec 470uF 35V
C303,C304 12005050 Capacitor Elec 470uF 35V
C407,C408 12005050 Capacitor Elec 470uF 35V
C912,C913 12005050 Capacitor Elec 470uF 35V
C907,C908 12005000 Capacitor Elec 6800uF 50V
C902 12005130 Capacitor Elec 220uF 25V
C215,C216 12001625 Capacitor Layer .68uF 50V
C405,C406 12001625 Capacitor Layer .68uF 50V
C909,C910 12001015 Capacitor Layer 0.33uF 50V
C203,C204 12001010 Capacitor M.P. 4.7uF 100V
C511, C512 12001010 Capacitor M.P. 4.7uF 100V
C102 12001080 Capacitor Mylar .22uF 50V
C507-C510 12004020 Capacitor P.P. 0.0047uF 50V
C501-C504 12004030 Capacitor P.P. 0.056uF 50V
C201,C202 12004050 Capacitor P.P. 100pF 100V
C207,C208 12003305 Capacitor P.P. 10pF 100V
C211, C212 12003710 Capacitor P.P. 150pF 63V
C209,C210 12003295 Capacitor P.P. 33pF 63V
C213,C214 12003300 Capacitor P.P. 47pF 63V
C601,C602 12001515 Capacitor Poly 100pF 160V
C505,C506 12001535 Capacitor Poly 47pF 160V
C403,C404 12001535 Capacitor Poly 47pF 16V
C401,C402 12003165 Capacitor Styrol 33pF 125V
X101 44000710 Ceramic Resonator
D901-908 16004003 Diode 1N4003
D101-108 16004148 Diode 1N4148
D911 16004148 Diode 1N4148
SCHEMATIC ADCOM PART NUMBER DESCRIPTION

3
LOCATION
D915-D917 16004148 Diode 1N4148
D909,D910 16005550 Diode J555
D912 16002222 Diode LM329DZ
IC102 21007100 IC 0AD 87C750
IC105,IC106 21008000 IC LT-1028CN8
IC601 21004556 IC NJM4556D
IC901 21007900 IC NJM7805FA
IC903 21007815 IC NJM7815FA
IC902 21007915 IC NJM7915FA
IC107-IC110 21000604 IC OPA604AP
IC103 21007457 IC TC74HC573N
IC104 21007404 IC TC74HCU04AP
JK106,JK107 22001570 IR REPEATER JACK
RY101-109 28000711 RELAY
RY902 28001120 RELAY
RY901 28001140 RELAY
R001,R002 27003010 Resistor 10 1/2W
R135,R136 27003010 Resistor 10 1/2W
R145 27003115 Resistor MOF 5% 150 1W
R609,R610 27002210 Resistor Roed 49.9
R137 27004590 Resistor Roed 82.5
R411,R412 27002010 Resistor Roed 100
R517,R518 27002010 Resistor Roed 100
R108,R109 27004380 Resistor Roed 150
R138-R144 27004380 Resistor Roed 150
R203,R204 27002120 Resistor Roed 261
R90627002140 Resistor Roed 332
R215,R216 27002170 Resistor Roed 475
R309,R310 27002170 Resistor Roed 475
R401,R402 27002170 Resistor Roed 475
R205,R206 27002190 Resistor Roed 499
R107 27002025 Resistor Roed 1.5K
R133 27002025 Resistor Roed 1.5K
R307,R308 27002040 Resistor Roed 100K
R103 27002030 Resistor Roed 10K
R111 27002030 Resistor Roed 10K
R128,R129 27002030 Resistor Roed 10K
R131 27002030 Resistor Roed 10K
R605,R606 27002030 Resistor Roed 10K
R903 27002030 Resistor Roed 10K
R403,R404 27002060 Resistor Roed 10M
R902 27002260 Resistor Roed 12.7K
R603,R604 27002280 Resistor Roed 15K
R207,R208 27004290 Resistor Roed 18K
R117-R120 27002020 Resistor Roed 1K
R134 27002020 Resistor Roed 1K
R303,R304 27002020 Resistor Roed 1K
R507-R512 27002020 Resistor Roed 1K
R301,R302 27002050 Resistor Roed 1M
R101,R102 27002095 Resistor Roed 2.2K

4
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
R104 27002095 Resistor Roed 2.2K
R413,R414 27002095 Resistor Roed 2.2K
R405,R406 27002710 Resistor Roed 2.49K
R217 27002340 Resistor Roed 2.4K
R209,R210 27002080 Resistor Roed 215K
R132 27002100 Resistor Roed 22K
R407,408 27002100 Resistor Roed 22K
R513,R514 27002100 Resistor Roed 22K
R607,R608 27002130 Resistor Roed 27K
R112 27001570 Resistor Roed 2K
R901 27002290 Resistor Roed 3.9K
R105,R106 27002410 Resistor Roed 4.75K
R114-R116 27002410 Resistor Roed 4.75K
R904,R905 27002200 Resistor Roed 4.9K
R110 27002180 Resistor Roed 47.5K
R130 27002180 Resistor Roed 47.5K
R201,R202 27002180 Resistor Roed 47.5K
R519,R520 27002180 Resistor Roed 47.5K
R501-R506 27002230 Resistor Roed 6.81K
R601,R602 27002230 Resistor Roed 6.81K
R305,R306 27002240 Resistor Roed 7.5K
R515,R516 27002240 Resistor Roed 7.5K
R113 27002370 Resistor Roed 8.25K
R211,R21227002250 Resistor Roed 82.5K
C905,C906 12001510 Spark Killer
SW2 37000711 Tone/Mono/Tape switch
Q107 33001345 Transistor 2SA1345-AC
Q101,Q102 33006080 Transistor 2SA608KF
Q904 33006080 Transistor 2SA608KF
Q108 33009840 Transistor 2SA984KE
Q110 33009840 Transistor 2SA984KE
Q106 33007640 Transistor 2SB764E/F
Q109 33002274 Transistor 2SC2274E/F
Q111 33002274 Transistor 2SC2274E/F
Q907 33002274 Transistor 2SC2274E/F
Q112-Q118 33003399 Transistor 2SC3399-AC
Q103 33005360 Transistor 2SC536KF
Q10533005360 Transistor 2SC536KF
Q903 33005360 Transistor 2SC536KF
Q906 33005360 Transistor 2SC536KF
Q901 33001100 Transistor TIP110
Q902 33001150 Transistor TIP115
VR2 35000710 Volume Pot
INPUT SELECTOR PCB TX70615
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
S2-S8 37001050 Key Sw w/LED

5
R121-R127 27002360 Resistor Roed 562
IR RECIEVER PCB TX706524
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
C101 12005020 Capacitor Elec 100uF 25V
IC101 21000710 Remote Reciever
POWER SWITCH PCB TX706534
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
JK108 22001030 Head Phone Jack
S1 37000710 Power Switch
VOLUME LED PCB TX706544
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
D401 16004266 LED Volume LTL-4266N
POWER CONNECTION PCB TX706554
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
12001605 Varistor TNR12G241K-BM
12001615 Varistor TNR12G431K-BY,BE
OTHERS
SCHEMATIC ADCOM PART NUMBER DESCRIPTION
LOCATION
25001060 AC Inlet
25001010 AC Outlet
15001120 AC POWER CORD
13001050 Bottom Plate
11001180 Button w/ hole
11001130 Button w/o hole
13001020 Foot
12000712 Front Chassis
13000710 Front Panel
19000100 FUSE 1A 250V
20003200 Fuse Holder
23001070 Volume Knob
23001000 Bass/Treble/Bal knob
11001155 Power Button
24000710 Power Transformer
13000711 Printed Rear Chassis
13000713 Side Chassis
13003032 Side Chassis (R)
11001170 Tact Button Connector

6
11001160 Tact Button Connector
13001040 Top Cover

6
a
GFP-710 VOLTAGE CONVERSION
115V TO 230V
1. The multivoltage GFP-710 units have a detachable power cord and no rear panel AC outlets.
2. Unplug the unit and remove the top cover.
3. On the AC primary board mounted at the far left of the unit, unsolder the jumper at the 115V
position and move it to the 230V position. Also, check the MOV position and type. Figure 1.
4. Change the rear panel fuse from 1A/250V to 500mA/250V. Also, remove the 1A/250V sticker
above the fuse holder so the 500mA/250V panel writing is visible.
5. Remove the 120V sticker at the far left of the rear panel so the 220-240V writing is visible.
AC4
AC3 AC2 AC1
AC5
115V
230V
Move jumper here
Figure 1: 220V Jumper position
230V TO 115V
1. The multivoltage GFP-710 units have a detachable power cord and no rear panel AC outlets.
2. Unplug the unit and remove the top cover.
3. On the AC primary board, mounted at the far left of the unit, unsolder the jumper at the 230V
position and move it to the 115V position. Also, check the MOV position and type. Figure 2.
4. Change the rear panel fuse from 500mA/250V to 1A/250V. Also, place a 1A/250V sticker above
the fuse holder to cover the 500mA 250V writing.
5. Place a 120V sticker at the far left of the rear panel to cover the 220-240V writing.
AC4
AC3 AC2 AC1
AC5
115V
230V
Move jumper here
Figure 2: 120V Jumper position
240V MOV should be here.
Type 12G431K.
Adcom part #:12001615.
6. Replace top cover and test unit.
6. Replace top cover and test unit.
120V MOV should be here.
Type 12G241K.
Adcom part #:(12001605).

7
GFP-710 SPECIFICATIONS
Output Impedence
Bypass Output........................................................................................................................................................... 100 ohms
Main outputs............................................................................................................................................................... 100 ohms
Tape Out.................................................................................................................................................................... 475 ohms
Output Level (Rated)
Bypass Output.................................................................................................................................................................... 2.0V
Main Outputs....................................................................................................................................................................... 2.0V
Output Level (Maximum)
Bypass Output................................................................................................................................................................≥10.0V
Main Outputs.................................................................................................................................................................. ≥10.0V
Frequency Response (+0.5 db)
High Level............................................................................................................................................................. 5Hz –50KHz
Phono.................................................................................................................................................................... 5Hz –50KHz
THD + Noise (@ Rated Output, 20Hz –20KHz)
High Level...................................................................................................................................................................... 0.005%
Phono............................................................................................................................................................................. 0.005%
IMD (SMPTE @ Rated Output)
High Level...................................................................................................................................................................... 0.005%
Phono............................................................................................................................................................................. 0.005%
Signal-to-Noise (@ Rated Output, “A” Weighted)
High Level.....................................................................................................................................................................≥100 db
Phono...............................................................................................................................................................................≥95 db
Input Impedence
High Level...................................................................................................................................................................25K ohms
Phono......................................................................................................................................................................47.5K ohms
Input Sensitivity (@ Rated Output)
High Level...................................................................................................................................................................... 205 mV
Phono............................................................................................................................................................................... 2.4mV
RIAA Accuracy (20Hz –20KHz)........................................................................................................................................ +/-0.25 db
Tape Output THD + Noise (@ Rated Output, 20Hz –20KHz)........................................................................................... 0.005%
Tape Output IMD (SMPTE @ Rated Output)....................................................................................................................... 0.005%
Tone Controls
Bass (20Hz).............................................................................................................................................................. +/-11.5 db
Phono (20KHz)........................................................................................................................................................... +/-8.5 db
Crosstalk (1 KHz)....................................................................................................................................................................... –80db
Seperation (1 KHz, @ Rated Output)...................................................................................................................................... ≥75db
Power Consumption...................................................................................................................................................... 10 watts max
Power (Available in 230VAC on special order).................................................................................................... 115VAC -50/60Hz
Chassis Dimensions................................................................................................ 3” (76mm) x 17” (432mm) x 11 3/8” (289mm)
Maximum Dimensions.................................................................................... 3 1/4” (83mm) x 17” (432mm) x 12 8/16” (319mm)
Weight.............................................................................................................................................................................. 12 lb. (5.5 kg)
Weight, Packed............................................................................................................................................................... 15 lb. (6.8 kg)