Brenell MINI 8 - Page 12

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3

5

Turn

the

replay

head

azimuth

alignment

screw

(see

fig.

A.l)

slowly

clockwise,

no

^Tthan

half

turn.

If

the

reading

on

the

millivoltmeter

falls

stop

and

turn

the

screw

in

the

opposit

direction.

The

millivoltmeter

will

r

to

a

maximum

and

then

fall.

Turn

the

screw

back

until

the

maximum

is

reach

.

4.

SETTING

THE

RECORD

HEAD

ROTATION

4.1

Exactly

the

same

procedure

as

in

section

3

azimuth

alignment

is

to

be

followed

except

that

adjustment

screws

are

to

be

used.

5.

SETTING

THE

REPLAY

HEAD

ROTATION

5.1

Exactly

the

same

procedure

as

in

section

4.

azimuth

alignment

is

to

be

followed

except

that

adjustment

screws

are

to

be

used.

setting

the

record

head

the

record

head

rotation

Setting

the

replay

head

the

replay

head

rotation

6.

REPLAY

FREQUENCY

RESPONSE

TOP

ADJUSTMENT

6.1

Provision

is

made,

on

each

channel

unit,

for

the

adjustment

of

the

^equency

response

at

the

top

end

of

the

bandwidth.

This

adjustment

is

only

effective

above

6kHz

and

gives

a

variation

of

±

1.5dB

up

to

14kHz.

6

2

The

frequency

response

section

of

the

calibration

tape

has

a

number

of

.

frequencies'recorded

on

it

between

31.5Hz

and

18kHz.

All

of

these

frequencies

can

be

used

to

check

that

the

frequency

response

of

the

repl

a

y

*

d

d

f

within

the

NAB

specification,

but

the

10kHz

frequency

is

used

as

the

standard

aligning

the

top

end

of

the

frequency

response.

6.3

set

the

calibration

tape

to

the

beginning

of

the

frequency

response

section.

6.4

Connect

an

AC

millivoltmeter

to

the

output

of

channel

one.

6.5

Start

the

calibration

tape

and

use

the

first

signal

on

the

tape

(a

1kHz

reference

signal)

to

set

the

output

level

control

on

the

channel

unit

to

on

the

millivoltmeter.

indicate

OdB

6.6

The

next

from

the

OdB

within

+

2dB

signal

on

the

tape

is

31.5Hz,

note

any

variation

in

output

level

reference

for

this

and

subsequent

frequencies.

They

should

all

of

this

level.

6

7

Should

the

deviation

from

the

reference

be

in

excess

of

+2dB

above

6-3kHz

thl

replay

top

should

be

adjusted

to

bring

the

level

within

this

range.

This

should

normally

be

carried

out

on

the

10kHz

frequency

signal.

6.8

If

subsequent

replays

of

frequency

response

section

of

the

calibration

tape

(there

are

two

repeats)

indicate

that

although

adjustment

has

brought

the

variationwittiin

^dB

at

10kHz

but

is

greater

at

other

frequencies,

then

replay

top

should

be

adjusted

at

the

frequency

showing

the

highest

variatio

.

X

may

result

tn

the

variation

at

10kHz

being,

say,

1.

dB

rather

thathe

0.5dB

that

was

achieved

when

the

adjustment

was

carried

at

lOkHz^

the

overall

variation

however

at

all

frequencies

will

still

be

within

+

2

.

6.9

Repeat

6.3

to

6.8

above

for

all

remaining

channels.

are

carried

out

with

the

tape

normally

used

on

the

tape

recorder.