Garrard mrm 101 service manual

Page 1

Service information for

Model MRM101

Music Recovery Module

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JAM-(49.44515;

Index

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Connections
Operation
Spare Dam list
Circuit diagram
Dismantling
Test procedures

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Details of authorised Garrard service makes are available On request.

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In USA:

Plessey Consume: Ptoducts
Garrard Dealer Sales Division,
100 Commercial Street. '
Plainview, New York 11803.

Telephone: (5161938 8900

Page 2

Model MRM101 Music Recovery Module

Introduction

The Music Recovery Module (referred to as MRM] is designed
to rem0ve the objectionable noises heard when a phone
pickup meets a scratch on the recOrd being played.

The MRM is not intended to remove all noises associated with
old, worn or generally dirty records. Since these noises occur
in an almost continuous manner. their detection could lead to
the removal of a substantial proportion of the original
recording.

The MHM contains a high quality stereo ore-amplifier with
magnetic phono inputs. This allows the MRM to be simply and
directly connected to the amplifier 'auxiliary' or 'tuner' inputs.
The scratch detection circuit recognises the whole waveform of

Specifications

Input

Suitable for pickup cartridges having an output of 0.7 to
2mV/cm/sec.

Input impedance

47k ohm.

Frequency response

: 1.568 20Hz to 20kHz (including equalisation network for
magnetic cartridgesl.

Dynamic range

Direct mode: greater than 100dB.

Via cuppreSSor: greater than 80dB (typically 85d8i.
lUnweighted 20Hz to 20kHz ref. to 1kHz maximum output I
Distortion

At "012 at nominal output:

Direct mode: Typically less than 0.01% T.H.D.

Via suppressor: Typically less than 0.1% T.H.D.

Channel balance

Better than 2dB at lIer.

Gerrard's policy is one of continued development and
therefore the Company reserves the right to alter specifications
without notice.

For Service and Enquiries:
Garrard Engineering Limited.
Sales Service Department.
Kembrey Street.

Swindon. Wiltshire SN2 68?.
Telephone Sw«ndon (0793) 41701

Connections

Connecting to the power supply

The power supply lead enters at the right hand side of the rear

panel.

Important: Before connecting to the power supply ensure by

the voltage instruction label on the back panel that the MRM is

suitable for the supply voltage.

1. United Kingdom only. A power- supply plug is not fitted and
as the colours of the wires in the mains lead of the MRM
may not correspond to the colours identifying the terminals
in your power supply plug proceed as follows:

The BROWN wire must be connected to the terminal in the
plug marked 1' or coloured red.

The BLUE wire must be connected to the terminal in the.
plug marked N or coloured black

A separate earth wire is not required.

If a 13 amp (BS1363) plug rs used. fit a 3 amp or 5 amp fuse.
For any other type of plug protect with a 5 amp fuse or fuse
wire in the adaptor or distributor board

2. Europe and U 8.A. A suitable 2 pin plug is provided for
connection to the power supply.

the scratch and distinguishes it from the peaks of the recorded
music. In order to allow the scratch detection circuit sufficient
time to make the decision to remove the scratch. the channels
are individually delayed by a few mini-seconds without limiting
the audio frequency range.

After recognising the scratch. a specially designed network
isolates the signal for sufficient time far the scratch noise to
pass out of the delay line.

Patents applied far.

WARNING: To prevent fire or shock hazard. do not expose this
appliance to rain or moisture.

Nominal output

300mV RMS.

Output

For 1% T.H.D. at 'lkHz:

Suppressor 'in' 2.5V rms.

Suppressor 'out 8V rms.

Output impedance

3.3k ohm.

Rated load impedance

Greater than 10k ohm (short circuit protected).
Power supply

120V AC, SOISOHZ 7VA. 0r 220/240V. AC SOISOHZ 7VA
Dimensions

378mm x 298mm x 71mm lW x D x H).
Shipping weight

3.7kg lateral.

Or. in USA:

Plessey Consumer Products.
Garrard Dealer Sales Division.
100 Commercial Street. .
Plainview. New York 11803.
Telephone: [516) 938-8900

Connections at the rear panel

Connections at the rear panel of the MHM are both RCA and
DIN type input and RCA type output sockets to provide the
facility to link up to any equipment likely to be used with it.
European versions also have a DIN type output socket.

The RCA connectors are identified 1. (left) and R (right). so that
a signal into the FI connector appears after processing on the Fl
output counector

For canvenience. the pickup input and the amplifier ouwut
connections are placed at either side of the signal earth I E- 1
terminal respectively.

It may be found advantageous to connect a lead bonneen the

amplifier cr record player and the MRM signal earth terminals.
to minimise hum.

Audio connecting leads (U K. and Europe)
The MHM Is supplied with an audio connecting lead specially
wired with a 5-pin DIN type plug at one end and RCA type