Adcom GFA-5300 Service Manual

Introduction . . . . . . . . . . . . . . . . 1 Test Procedures . . . . . . . . . . . . . 1 Parts List . . . . . . . . . . . . . . . . . . 2 Specifications . . . . . . . . . . . . . . . 5 Chassis Layout . . . . . . . . . . . . . . . 5 PCB Layout . . . . . . . . . . . . . . . . . . 7 Wiring Diagram. . . . . . . . . . . . . . . . 8 Schematic . . . . . . . . . . . . . . . . . 9 10 Timber Lane Marlboro, NJ 07746 USA Tel: 732-683-2356 Fax: 732-683-9790 Web: http://www.adcom.com

performance of, adjusting, and repairing the ADCOM GFA-5300 amplifier. The procedures described here are not intended for persons unfamiliar with the appropriate safety and test procedures. TEST PROCEDURES • All tests are performed with a 115V, low-distortion (less than 2% THD), AC-power source, 8-ohm resistive load (except slew rate), and a signal source of not more than 600 ohms. • An 80kHz low-pass filter is employed during THD distortion measurements. • Signal-to-noise measurements are “A” weighted. • Damping factor is measured by comparing the 1 watt output voltage with and without an 8 ohm load. • Slew rate is measured with an inductive load, and is derived with a dual-time-based oscilloscope reading the slope of a full power 5kHz square wave. DO NOT OPERATE THE AMPLIFIER AT FULL-POWER SINE WAVE ABOVE 22kHz OR FULL-POWER SQUARE WAVE ABOVE 5kHz. CORRECT BIAS ADJUSTMENT IS CRITICAL TO THE PERFORMANCE OF THIS AMPLIFIER. MAXIMUM OUTPUT POWER, MINIMUM THD AND HEAT DISSIPATION ARE AFFECTED BY THE BIAS SETTING AND MUST BE CORRECT TO MAINTAIN THE SONIC QUALITY AND LONGEVITY OF THE AMPLIFIER. BIAS ALIGNMENT Prior to performing BIAS ALIGNMENT turn unit on and allow to idle with rated output (8 ohm) for approximately 5 MINUTES before attempting adjustments Bias Adjustment Connect voltmeter across emitter resister R038 (R138 for right channel) and adjust R043 (R143 for right channel) to read 20mV +/-2mV DC Offset Connect voltmeter across the speaker outputs and adjust R042 (R142 for right channel) to read 0mV +/- 10mV WARNING THERE ARE POTENTIALLY LETHAL VOLTAGES WITHIN THE GFA-5300 AMPLIFIER WHICH WILL BE ACCESSIBLE ONCE ITS TOP COVER IS REMOVED. DO NOT ATTEMPT FAMILIARIZATION, INSPECTION, OR ANY PROCEDURE WHATSOEVER UNLESS YOU HAVE DISCONNECTED THE GFA-5300 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 GFA-5300 UNLESS YOU ARE TECHNICALLY QUALIFIED TO DO SO. IMPORTANT BEFORE PROCEEDING WITH ADJUSTMENTS, MAKE SURE AMPLIFIER IS AT ROOM TEMPERATURE.

AMPLIFIER PCB FOR RIGHT CHANNEL REPLACE 0XX WITH 1XX SCHMATIC ADCOM PART NUMBER DESCRIPTION LOCATION C001 12005385 CAPACITOR ELEC 47uF 63V C002 12001415 CAPACITOR POLY 39pF 50V C004 12001275 CAPACITOR MYLAR 2.2uF 250v C005 12005325 CAPACITOR ELEC 4.7uF 50V C006 12001425 CAPACITOR POLY 390pF 50V C007 12005385 CAPACITOR ELEC 47uF 63V C008 120012025 CAPACITOR MYLAR 1uF 250V C010 XXXXXX CAPACITOR CTC 18pF C011 12001235 CAPACITOR MYLAR 0.1uF 250V C012 12005385 CAPACITOR ELEC 47uF 63V C013 12002155 CAPACITOR CEREMIC 0.1uF 50V C014 12005380 CAPACITOR ELEC 47uF 25V C015 12005090 CAPACITOR ELEC 10uF 25V C016 12001240 CAPACITOR MYLAR 0.01uF 50V C017 12005160 CAPACITOR ELEC 22uF 25V C018 12002030 CAPACITOR CEREMIC 5pF 50V C019,C020 12001305 CAPACITOR MYLAR 0.22uF 250V C021,C022 XXXXX CAPACITOR ELEC 470uF 63V C023,C024 12005010 CAPACITOR ELEC 1000uF 25V D001-D005 16000082 DIODE ZENER 8.2V D006 16004148 DIODE 1N4148 D007,C008 16000082 DIODE ZENER 8.2V D009 16001254 DIODE LTL1254 (YELLOW) D010 16001204 DIODE LTL1204 (RED) D011 16004148 DIODE 1N4148 D012-D016 16004003 DIODE 1N4003 D058 16003600 DIODE ZENER 3.6V M001,M002 19009400 FUSE T4A 125V M006 32005200 THERMAL BREAKER UP72 85 DEGREE Q001,Q002 33000992 TRANSISTOR 2SA992 Q003 33009210 TRANSISTOR IRFD9210 Q004 33001845 TRANSISTOR 2SC1845 Q005 33000992 TRANSISTOR 2SA992 Q006 33009610 TRANSISTOR IRF9610 Q007-Q009 33002100 TRANSISTOR IRFD210 Q011,Q012 33000610 TRANSISTOR IRF610 Q013,Q015 33002400 TRANSISTOR IRFP240 Q014,Q016 33000924 TRANSISTOR IRFP9240 Q017-Q019 33001845 TRANSISTOR 2SC1845 Q020 33000992 TRANSISTOR 2SA992 Q021 33008050 TRANSISTOR KTC8050 Q022 33008550 TRANSISTOR KTC8550 R003 27004620 RESISTOR 7.5K R004 27001515 RESISTOR 4.7R R005 27004265 RESISTOR 2.2K R006 27004640 RESISTOR 1.5K

LOCATION R008 27004570 RESISTOR 221R R010,R012 27004200 RESISTOR 10K R013 27004570 RESISTOR 221R R014 27004300 RESISTOR 15K R015 27004110 RESISTOR 2K R016 27004135 RESISTOR 4.99K 1/2W R017 27004570 RESISTOR 221R R018 27004400 RESISTOR 1.82K R019 27004600 RESISTOR 4.75K R020,R021 27004500 RESISTOR 49.9K R022 27004200 RESISTOR 10K R023 27004400 RESISTOR 1.82K R024 27004600 RESISTOR 4.75K R026,R027 27004570 RESISTOR 221R R028 27003200 RESISTOR 5.1R 2W R030 27004225 RESISTOR 475R R031 27004670 RESISTOR 100R R034-R037 27004570 RESISTOR 221R R038-R041 27006095 RESISTOR 0.33R 3W R042 35001355 DC OFFSET VR 5K R043 35001355 BIAS VR 5K R044 27004500 RESISTOR 49.9K R045,R046 27004670 RESISTOR 100R R047 27004200 RESISTOR 10K R050 27004160 RESISTOR 47.5K R051 27004050 RESISTOR 1K R052 27004435 RESISTOR 22R R053 27004500 RESISTOR 49.9K R054 27004200 RESISTOR 10K R055 27004265 RESISTOR 2.2K R056 27004630 RESISTOR 220K R057 27004050 RESISTOR 1K R058 27004071 RESISTOR 5.1K R059 27001160 RESISTOR 33K R060 27004500 RESISTOR 49.9K R061 27004570 RESISTOR 221R R062,R063 XXXXXX RESISTOR 56R R064 27004570 RESISTOR 221R R065,R066 27003010 RESISTOR 10R 1/2W R067,R068 27004071 RESISTOR 5.1K R069,R070 27003010 RESISTOR 10R 1/2W U001 21005550 IC LM555

SCHMATIC ADCOM PART NUMBER DESCRIPTION LOCATION C201 12005700 SPARK KILLER 4700pF 400V C202,C203 12005005 CAPACITOR ELEC 10000uF 63V C204,C205 12001235 CAPACITOR MYLAR 0.1uF 250V C206,C207 12005005 CAPACITOR ELEC 10000uF 63V C208,C209 12001235 CAPACITOR MYLAR 0.1uF 250V C210 12005010 CAPACITOR ELEC 1000uF 25V C211 12005120 CAPACITOR ELEC 220uF 16V D201,D202 16002504 BRIDGE RECTIFIER KPCB2504 D203-D207 16004003 DIODE 1N4003 D302 16001204 POWER LED LTL1204 (RED) M207 37005200 POWER SWITCH SDDFA3066A NR01 31005200 THERMISTOR 5R/8A R201,R202 27003280 RESISTOR 8.2K 1W R203,R204 27003300 RESISTOR 10R 2W R205,R206 27003280 RESISTOR 8.2K 1W R207 27001480 RESISTOR 5.6K 2W U201 21007812 REGULATOR IC 7812 V201 EURO 12001610 VARISTOR TNR9G391K V201 USA 12001230 VARISTOR TNR9G221K OTHERS SCHMATIC ADCOM PART NUMBER DESCRIPTION LOCATION T1 24005300 MAIN TRANSFORMER 1806-2116-2 T2 24005201 STANDBY TRANSFORMER 1806-2196-0 F201 EURO 19000315 MAIN FUSE 3.15A 250V F201 USA 19000600 MAIN FUSE 6A 125V M202 EURO 19009050 STANDBY FUSE T.5A 250V M202 USA 19009050 STANDBY FUSE T.5A 250V 13005301 FRONT PANEL 13005300 TOP COVER 13005304 HEAT SINK 47002580 LED HOLDER 13005206 FOOT 15001050 POWER CHORD 11001155 POWER BUTTON 11001165 POWER BUTTON FRAME 20005300 MAIN FUSE HOLDER

Certain versions of the GFA-5300 are cabable of operating at multiple voltages.The conversion described below is for multivoltage versions of the GFA-5300. Multivoltage versions of the GFA-5300 have removable power cords. Converting from 115VAC to 230VAC 1) With the Unit unplugged, remove the top cover of the GFA-5300. 2) Locate the Power and Standby PCBs at the front of the unit (pictured below). 3) Remove jumpers J201, J202, J204 and J205. 4) Add jumpers J203 and J206. 5) Replace the rear panel 6A main fuse with a 3A fuse. 6) Add sticker to back of unit indicating new operating voltage and fuse rating. 7) Replace top cover and test on 230VAC source. Converting from 230VAC to 115VAC 1) With the unit unplugged, remove the top cover of the GFA-5300. 2) Locate the Power and Standby PCBs at the front of the unit (pictured below). 3) Remove jumpers J203 and J206. 4) Add jumpers J201, J202, J204 and J205. 5) Replace the rear panel 3A main fuse with a 6A fuse. 6) Add sticker to back of unit indicating new operating voltage and fuse rating. 7) Replace top cover and test on 115VAC source. Figure 1 - GFA-5300 Power and Standby PCBs showing J201 - J206 J202 J203 J201 J206 J205 J204

80 watts continuous average power per channel into 8 ohms at any frequency between 20Hz to 20kHz with all channels driven at less than 0.18% THD 125 watts continuous average power per channel into 4 ohms at any frequency between 20Hz to 20kHz with all channels driven at less than 0.18% THD IM Distortion (SMPTE) 1 watt to 80 watts into 8 ohms ..................................................................................................................................... ≤ 0.07% 1 watt to 125 watts into 4 ohms................................................................................................................................... ≤ 0.07% IM Distortion (CCIF, Any Combination from 4kHz to 20kHz) 80 watts into 8 ohms .................................................................................................................................................. ≤ 0.035% 125 watts into 4 ohms................................................................................................................................................ ≤ 0.035% THD + Noise at 80 watts into 8 ohms (Typical) 20Hz............................................................................................................................................................................... 0.018% 1kHz ................................................................................................................................................................................. 0.02% 10kHz............................................................................................................................................................................... 0.07% 20kHz............................................................................................................................................................................... 0.14% THD + Noise at 125 watts into 4 ohms (Typical) 20Hz............................................................................................................................................................................... 0.018% 1kHz ................................................................................................................................................................................. 0.02% 10kHz............................................................................................................................................................................... 0.08% 20kHz............................................................................................................................................................................. 0.165% Frequency Response @ 1 Watt into 8 ohms (10Hz to 20kHz).................................................................................. +0, -0.25dB Power Bandwidth (-3dB) ............................................................................................................................................ 3Hz to 130kHz Dynamic Headroom into 4 ohms............................................................................................................................................ 2.1 dB Signal to Noise Ratio, “A” Weighted (80 watts into 8 ohms).......................................................................................... ≥ 100dB Gain...... .......................................................................................................................................................................................... 29dB Input Sensitivity for 1 Watt ...................................................................................................................................................................... 0.1 volts for 80 Watts .................................................................................................................................................................. 0.9 volts Input Impedance ....................................................................................................................................................................... 49.9kΩ Damping Factor (20Hz to 20kHz)............................................................................................................................................. ≥ 350 Rise Time (5kHz, 90V, peak-to-peak square wave, 20% to 80%)....................................................................................... 1.8µS Power Consumption (Continuous, All Channels Driven) Quiescent........................................................................................................................................................................ 100VA Maximum......................................................................................................................................................................... 720VA 80 watts into 8 ohms ...................................................................................................................................................... 510VA 125 watts into 4 ohms.................................................................................................................................................... 720VA Power (Available in 230VAC on special order).................................................................................................... 115VAC - 50/60Hz Chassis Dimensions....................................................................................... 4 1/2” (105mm) x 17” (432mm) x 11 3/8” (289mm) Maximum Dimensions.................................................................................... 4 3/8” (111mm) x 17” (432mm) x 12 1/8” (308mm) Weight.. .......................................................................................................................................................................... 22 lb. (10.0 kg) Weight, Packed............................................................................................................................................................. 25 lb. (11.3 kg)