Shure M-64-A Service manual

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Shure M-64-A Service manual

lnput lmpedance (at 1 kHz) Resistance: 50 kilohms Capacitance: 160 picofarads

Output Impedance (at 1 kHz)

High Level: Less than 2000 ohms (minimum recommended load is 22,000 ohms)

Low Level: 600 ohms (any load on Low Level output will not affect input clipping level)

Power Consumption

5 watts

Operating Voltage

120 or 240 volts ac + 1O0/0,50160 Hz (internally selectable)

Temperature Range

Operating: -7" to 57" C (20" to 135" F)

Storage: -29" to 71" C (-20" to 160" F)

Dimensions

See Figure 2

Net Weight

986 grams (1 Ib 2-112 oz)

144mm

1 0 4 m m

r ( 5 - 9 / 1 6 IN . )

1( 4 - 3 / 3 2 I N . I ~

OVERALL DIMENSIONS

FIGURE 2

INSTALLATION

To reduce the risk of fire or electric shock, do not expose this appliance to rain or extreme moisture.

The M64A can be operated on any flat surface, or (with adequate space) be mounted to an amplifier chassis or cabinet using screws through the M64A's mounting flanges. The unit can be mounted in any position for normal operation, but for best results, it should be located away from motors, lighting dimmers, or other hum-producing power sources and away from intense heat sources.

Should hum be encountered in a sound system or installation, one or more of the equipment power plugs may be reversed to reduce hum. If the turntable has a grounding lead, this wire can be connected to the M64A Ground screw to reduce hum pickup.

OPERATION

WARNING

Use of the M64A with power amplifiers of the transformerless (ac-dc) type may result in a shock hazard. A suitable power line isolation transformer should be used with such equipment.

1.Set the selector switch to the desired function (Phono, Flat or Tape).This automatically selects the proper equalization (frequency response) for both channels.

2.For the equalized Phono (RIAA) or Tape (NARTB) positions, connect the signal leads from the phono cartridge or tape head to the M64A jacks marked Channel 1 lnput and Channel 2 Input. Note that the Flat position can be used for phono cartridge or tape head buffering applications in which the M64A output is connected to an equalized amplifier input.

3.For the Flat position using two high-impedance microphones, connect each microphone cable to one of the M64A lnput connectors. If a single highimpedance microphone is used, connect it to either lnput connector. NOTE: If low-impedance microphones are to be used, a suitable line matching transformer such as Shure'sA95 Series should be used.

4.Refer to the phono cartridge, tape head or microphone data sheet for details on connections, phasing and grounding.

5.Connect the Channel 1 and Channel 2 Output jacks (High or Low Level) to the corresponding input jacks of the power amplifier, preamplifier, tape recorder or mixer. The High Level outputs can be connected to high-level auxiliary inputs, and the Low Level outputs can be connected to low-level microphone inputs (or equalized phono or tape head inputs in buffering applications).

6.If grounding is necessary,the associated equipment ground lead can be attached to the M64A Ground screw.

7.Insert the M64A power line cord into a proper power outlet (120 Vac +lo%, 50160 Hz), preferably one controlled by the power amplifier's on-off switch. Make certain the M64A Power switch is turned on if the unit is to be remotely turned on and off.

SERVICE

WARNING

Voltages in this equipment are hazardous to life. Refer servicing to qualified service personnel.

Balanced Line Output

For professional low-impedance balanced-line use such as broadcast systems or recording consoles, an external line matching transformer such as Shure'sA95 Series can be added to each M64A High Level output. The resultant output level is approximately -32 dBm. If

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