Shure VA 300 manuale d’uso

VA 300 OPERATING AND SERVICE MANUAL Manufactured by SHURE BROTHERS INC. 222 Hartrey Avenue Evanston, Illinois 60204 U. S. A. Copyright 1978, Shure Brothers Inc. AL404 (RE) 27A819 Printed in U. S. A.[...]

VA300 SPECIFICATIONS VA300-C Console Amplifier Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . All silicon transistor mixer/power amplifier Power Output . . . . . . . . . . . 100 watts continuous (RMS); (to 8 ohm load, see Figure 3, Page 7) Voltage Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 db “Mic.” Input Level [...]

VA300-C Console (cont’d) Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 volts, 60 Hz. 80 watts maximum with no signal in. 180 watts with 1 KHz. signal and 100 watts output 400 watts maximum operating -7°C to 43°C (20°F to 110°F) without derating Power Consumption . . . . . . . . . . . . . . . . . . . Ambien[...]

Figure 1 Front Panel Controls (Refer to Figure 1) 6. Individual Channel “Treble & Bass” Controls (Six, Dual 1. “Anti-Feedback” Switches (Four). 2. “Reverb Intensity” Control. 3. “Reverb Treble & Bass” Controls (Dual Concentric). 4. “Master Reverb” Switch. 5. Individual Channel “Volume” Controls (Six). Concentric). 7.[...]

VA300 Vocal Master OPERATING INSTRUCTIONS General Operating Instructions: 1. Set all front panel controls in the following manner: All switches (1), (4). (7). set to “Out” position; “Reverb Intensity” Control (2). and all “Volume” Controls (5) and (8), set at “0”; all “Treble” and “Bass” Controls (3) and (6). set in the “f[...]

Input Connections: Six individual input connectors are provided on the rear panel of the Console. These connectors are standard 1/4 inch phone jacks (22). The Console is designed to operate with any high quality dynamic or ribbon-type high impedance micro- phone. High impedance microphone cables should be limited to a maximum length of 6m (20 ft) t[...]

Figure 3. Typical output power vs. speaker load impedance for the VA300 Vocal Master Column Speaker Placement: It must always be kept in mind that every room or space is acoustically unique and there are no set “rules” for speaker placement. A number of generalizations however may be made which will at least provide a good starting point under [...]

Thermal Overload/Ventilation: The VA300 is equipped with thermal sensing switches on the heat-sinks of the output transistors. The thermal switches are set to shut off AC power to the amplifier when a temperature of 90°C (194°F) is attained on the heat-sinks; the switches will automatically recycle and return AC power when the heat-sink temperatu[...]

A phone jack marked “Reverb Switch” (17) is located on the rear panel of the console. This jack parallels the Master Reverb In-Out switch (4) and allows the reverb to be remotely turned on and off when the Master Reverb switch is in the “In” position. The Master Reverb switch will always override the remote switch and turn off the reverb, s[...]

Phonographs: To connect a” phonograph having a magnetic cartridge, and no preamplifier, to the VA300, attach a cable from the phonograph output to one of the six Input jacks on the Console. Set that channel’s Input Attenuator Switch to the “Mic.“ position. Set the Treble control for that channel at 9:00 o’clock and the Bass control at 3:0[...]

Adjust the Echo Gain control and the mixer volume con- trols to match the gain of the VA300 inputs. With the mixer connected in this configuration the individual Reverb In-Out switches on the Console should be set to the “In” position. When these switches are set to the “Out” position, that indi- vidual channel will be muted, or “cued.”[...]

Set the controls on the second VA300 Console as follows: Antifeedback Switches to “Out,” Master Reverb Switch “Out,” Individual Volume Controls to “0,” and the Master Volume to “5.” Adjust the Echo “Gain” Control to approximately 1/3 rotation from the c.c.w. off position, and use this control as a volume control to obtain the sa[...]

VA300-C FUNCTIONAL DIAGRAM Figure 11 VA300 Vocal Master SERVICE INSTRUCTIONS Amplifier Service (See Guarantee): The VA300 Vocal Master Console uses components of the highest quality, operating well within their respective ratings to assure long life. CAUTION: There are no user serviceable parts inside. Refer servicing to qualified service personnel[...]

Driver Transistors: Figure 12 Output Transistors: The driver transistors Q33 and Q34, Figure 12, Page 14 are located on the amplifier chassis. Before removing these transistors, write down the lead color and location at each transistor solder junction. If replacing transistors, apply type 120 Wakefield thermal joint compound to each side of the ins[...]

Figure 13 Figure 14 Small Signal and Predriver Transistors: Transistors Q1 through Q30, Figure 14, Page 15 and Q31 and Q32, Figure 12, Page 14 are mechanically supported by their leads. When replacing these transistors, it is imperative that proper lead configuration be followed. A minimum of sold- ering heat should be used to avoid damage to the t[...]

OHMMETER CONNECTIONS OHMMETER READING “Plus” Lead “Minus” Lead Collector Emitter Collector Emitter Base Base Emitter Collector Base Base Collector Emitter N.P.N. Transistor P.N.P. Transistor High High High High Low Low High High Low Low High High With the ohmmeter “plus” probe on the anode end of a diode, and the “minus” probe on th[...]

VA300-S Speaker Servicing: 1. Unplug cables from speaker jacks. 2. Remove back of cabinet. 3. Disconnect one end of the lead connected between the two 10 inch loudspeakers. 4. Apply 60 Hz, 1 to 10 volts, to each of the six speakers individually. Any buzzes or rattles indicate possible failure. The speakers should all sound generally alike with a sl[...]

REPLACEMENT PARTS LIST FOR VA300-C CONSOLE ** REPLACEMENT KIT CONSISTS OF: ITEM REPL. KIT NO. QTY. PART NO. DESCRIPTION C1 RKC26 1 86A631 Capacitor, 2500 x 100 C2 RKC27 1 86B631 Capacitor, 4000 x 60 D1-D4 RKC46 4 86A406 Silicon Rectifier, 3A., 200V. D5 RKC22 1 86A408 Zener Diode, 22V., 1 W., 5% D6, 7 RKC50 2 86A410 Silicon Rectifier, 100 V. ½A D8,[...]

ALTERNATE POWER SUPPLY INCORPORATED IN EARLY PRODUCTION UNITS Figure 17 19[...]

Notes to Circuit Diagram D.C. Voltage Measurements: Check the DC voltages first, because any deviation from the nominal voltages will affect the AC voltage. In the power amplifier section, Q31 to Q38, the key DC voltages are +94 (collector of Q33, Q35, and Q37). +22 (collector of Q31), and the split voltage at the junction of R17, R19, R20, and R22[...]

VA300-C CIRCUIT DIAGRAM ISSUE 6 21 Figure 18[...]