Drawmer 1961 User Manual

1961

VACUUM TUBE EQUALISER

OPERATORS MANUAL

CONTENTS

SAFETY CONSIDERATIONS page 1
POWER CONNECTION page 2
INSTALLATION page 2
FUSES page 3
INTRODUCTION page 4
APPLICATIONS page 5
CONTROL DESCRIPTIONS page 5
OPERATION page 7
IF A FAULT DEVELOPS page 10
CONTACTING DRAWMER page 10
TECHNICAL SPECIFICATION page 11
BLOCK DIAGRAM page 12

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COPYRIGHT

This manual is copyrighted © 1995 by Drawmer Electronics, Ltd. W ith all rights
reserved. Under copyright laws, this manual may not be duplicated in whole or in
part without the written consent of Drawmer.

ONE YEAR LIMITED WARRANTY

Drawmer Electronics Ltd., warrants the Drawmer 1961 audio processor to
conform substantially to the specifications of this manual for a period of one year
from the original date of purchase when used in accordance with the
specifications detailed in this manual. In the case of a valid warranty claim, your
sole and exclusive remedy and Drawmer’s entire liability under any theory of
liability will be to, at Drawmer’s discretion, repair or replace the product without
charge, or, if not possible, to refund the purchase price to you. This warranty is
not transferable. It applies only to the original purchaser of the product.

For warranty service please call your local Drawmer dealer. Alternatively call
Drawmer Electronics Ltd. at [phone]. Then ship the defective
product, with transportation and insurance charges pre-paid, to Drawmer
Electronics Ltd., Coleman Street, Parkgate, Rotherham, S62 6EL UK. W rite the
RA number in large letters in a prominent position on the shipping box. Enclose
your name, address, telephone number, copy of the original sales invoice and a
detailed description of the problem. Drawmer will not accept responsibility for loss
or damage during transit.

This warranty is void if the product has been damaged by misuse, modification or
unauthorised repair.

THIS WARRANTY IS IN LIEU OF ALL WARRANTIES, W HETHER ORAL OR
WRITTEN, EXPRESSED, IMPLIED OR STATUTORY. DRAWMER MAKES NO
OTHER WARRANTY EITHER EXPRESS OR IMPLIED, INCLUDING, WITHOUT
LIMITATION, ANY IMPLIED W ARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. PURCHASER’S
SOLE AND EXCLUSIVE REMEDY UNDER THIS WARRANTY SHALL BE REPAIR
OR REPLACEMENT AS SPECIFIED HEREIN.

IN NO EVENT W ILL DRAWMER ELECTRONICS LTD. BE LIABLE FOR ANY
DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
RESULTING FROM ANY DEFECT IN THE PRODUCT, INCLUDING LOST
PROFITS, DAMAGE TO PROPERTY, AND, TO THE EXTENT PERMITTED BY
LAW, DAMAGE FOR PERSONAL INJURY, EVEN IF DRAWMER HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

Some states and specific countries do not allow the exclusion of implied
warranties or limitations on how long an implied warranty may last, so the above
limitations may not apply to you. This warranty gives you specific legal rights. You
may have additional rights that vary from state to state, and country to country.

In the interests of product development, Drawmer reserve the right to modify or
improve specifications of this product at any time, without prior notice.

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1961 OPERATORS’ MANUAL 1

DRAWMER 1961

VACUUM TUBE EQUALISER

SAFETY CONSIDERATIONS

CAUTION - MAINS FUSE

TO REDUCE THE RISK OF FIRE REPLACE THE MAINS FUSE ONLY WITH A

FUSE THAT CONFORMS TO IEC 127-2. 250 VOLT WORKING, TIME DELAY

TYPE WITH A BODY SIZE OF 20mm x 5mm.

THE MAINS INPUT FUSE MUST BE RATED AT 250mA WHERE THE MAINS
INPUT VOLTAGE SWITCH IS SET TO 230 VOLTS AC. AND 500mA WHERE

THE MAINS INPUT VOLTAGE IS 115 VOLTS AC.

THE REAR PANEL H.T. FUSE MUST ALWAYS BE RATED AT 50mA,

IRRESPECTIVE OF THE MAINS VOLTAGE SETTING.

CAUTION - MAINS CABLE

DO NOT ATTEMPT TO CHANGE OR TAMPER WITH THE SUPPLIED MAINS

CABLE.

CAUTION - SERVICING

DO NOT PERFORM ANY SERVICING. REFER ALL SERVICING TO

QUALIFIED SERVICE PERSONNEL.

WARNING

TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK DO NOT EXPOSE

THIS EQUIPMENT TO RAIN OR MOISTURE.

1961 OPERATORS’ MANUAL2

POWER CONNECTION

The unit will have been supplied with a power cable suitable for domestic power
outlets in your country. For your own safety it is important that you use this cable.
The unit should always be connected to the mains supply earth using this cable.

If for some reason the unit is to be used at a mains input operating voltage which is
different to that as supplied, the following procedure must be carried out. (See

following diagram)

1: Disconnect the unit from the mains.
2: Using a number 1 size pozidrive screwdriver, remove the two self-tapping
screws holding the voltage selection switch cover plate on the rear panel.
3: Remove the cover plate and slide the switch fully to its opposite end.
4: Rotate the cover plate one half turn, (180E ) and refit the two screws.

5: Fit a correctly rated fuse for the selected operation voltage.

6: Reconnect to mains power source.

INSTALLATION

The 1961 is designed for standard 19" rack mounting and occupies 2U of rack space.
Fibre or plastic washers may be used to prevent the front panel becoming marked by
the mounting bolts. Because the tube circuitry generates more heat than an
equivalent solid-state design, we recommend space be left above the unit to allow
the heat to dissipate.
! Care should be taken in the choice of positioning. The unit should not be

mounted where other equipment obstructs the normal air flow. The unit should
not be situated near any heat source, such as a radiator, stove or a high
power amplifier that would generate heat.

! The appliance should not be operated near any water or in a location where

moisture might be present.

! Always connect the mains earth to the unit.

If the 1961 is to be continuously moved from one location to another, we suggest
using additional support in the rack at the rear of the unit.

1961 OPERATORS’ MANUAL 3

FUSES

The mains fuse should be a class 3, 250 Volt, Time delay type, with a body size of
20mm x 5mm, at the correct rating for the mains input voltage. It is very important
that this f use complies with IEC127-2. Remember that, in the unlikely event of the
unit developing a fault, it is normal for the mains fuse to blow and the unit must be
serviced by a qualified service technician.

For added protection the 1961 is also fitted with silicon re-setable fuses. Under
certain conditions, - eg. intermittent mains power, faulty mains cable - these fuses
will 'trip', effectively removing power from the internal circuitry. If this should happen,
the silicon fuses will automatically reset after switching off the unit for 15 to 30
seconds and then switching back on again. The fuses will probably never trip.
Occasionally the fuses might trip repetitively due to an internal fault, in which case
the unit will need attention from a service technician before the silicon fuses will
reset.

AUDIO CONNECTIONS

The inputs and outputs are electronically balanced XLRs where pin 1 is screen, pin 2
hot, pin 3 cold and the XLR shell is connected to chassis. The operating level is
nominally +4dBu. Balanced use is recommended. The 1961 f ully conforms to the
EMC standards, if you propose to use the unit where it maybe exposed to high levels
of disturbance such as f ound close to TV and radio transmitters we suggest that the
screen of the signal cable is connected to the chassis connection on the XLR type
connector.

A further connection point is provided in the form of the Audio Insert jack on the rear
panel. T his is a stereo jack socket wired such that the Ring carries the input to the
1961 and the Tip carries the output. W hen a plug is inserted, the XLR input f or that
channel is disconnected. The Audio Insert point may be connected directly to the
side-chain access point of a Drawmer 1960 using a stereo jack cable wired with
screened cable where the tip connects to the tip; ring connects to ring and the screen
is connected at both ends. Alternatively, the same type of stereo jack lead may be
used to connect the 1961 Audio Inserts to the +4dBU Signal Insert point of the 1960
allowing the two units to be used in series. In this latter configuration, only the
balanced audio connections of the 1960 are used; the 1961 is connected only via its
Audio insert points.

If earth loop problems are encountered, do not disconnect the mains earth. Try
disconnecting the signal screen on one of the cables connecting the outputs of the
1961 to the patchbay. If such measures are necessary, balanced operation is
recommended.