Adcom GFA-5300 Service Manual

SERVICE MANUAL
2 CHANNEL
POWER AMPLIFIER
GFA-5300
TABLE OF CONTENTS
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

Adcom GFA-5300 Specifications

Power

power rating into 8 ohms	80 watts continuous average power per channel
power rating into 4 ohms	125 watts continuous average power per channel
power consumption - quiescent	100 VA
power consumption - maximum	720 VA
power consumption - 80 watts into 8 ohms	510 VA
power consumption - 125 watts into 4 ohms	720 VA
power supply voltage	115 VAC - 50/60 Hz

Distortion and Noise

IM distortion SMPTE 8 ohms	≤ 0.07%
IM distortion SMPTE 4 ohms	≤ 0.07%
IM distortion CCIF 8 ohms	≤ 0.035%
IM distortion CCIF 4 ohms	≤ 0.035%
THD + Noise at 80 watts into 8 ohms 20Hz	0.018%
THD + Noise at 80 watts into 8 ohms 1kHz	0.02%
THD + Noise at 80 watts into 8 ohms 10kHz	0.07%
THD + Noise at 80 watts into 8 ohms 20kHz	0.14%
THD + Noise at 125 watts into 4 ohms 20Hz	0.018%
THD + Noise at 125 watts into 4 ohms 1kHz	0.02%
THD + Noise at 125 watts into 4 ohms 10kHz	0.08%
THD + Noise at 125 watts into 4 ohms 20kHz	0.165%
signal to noise ratio (A weighted)	≥ 100 dB

Frequency and Gain

frequency response	+0, -0.25 dB from 10Hz to 20kHz
power bandwidth	3Hz to 130kHz
dynamic headroom into 4 ohms	2.1 dB
gain	29 dB

Input and Output

input sensitivity for 1 watt	0.1 volts
input sensitivity for 80 watts	0.9 volts
input impedance	49.9 kΩ
damping factor	≥ 350
rise time	1.8 µS

Weight and Dimensions

chassis dimensions	4 1/2” x 17” x 11 3/8” (105mm x 432mm x 289mm)
maximum dimensions	4 3/8” x 17” x 12 1/8” (111mm x 432mm x 308mm)
weight	22 lb. (10.0 kg)
weight, packed	25 lb. (11.3 kg)

Summary

Introduction

Bias Alignment

Bias Adjustment

Procedure to adjust bias voltage across emitter resistor R038/R138 using R043/R143.

DC Offset

Procedure to adjust DC offset voltage across speaker outputs using R042/R142.

Test Procedures

Service Parts List

Amplifier PCB Components

Component list for the Amplifier PCB, detailing schematic location, ADCOM part number, and description.

Main and Standby Power Supply PCB Components

Component list for the Main and Standby Power Supply PCB, including schematic location and part numbers.

Other Components

List of other components and parts for the ADCOM GFA-5300 amplifier, including fuses and transformers.

Voltage Conversion

Specifications