Roberts 990 997Service Manual

Page 1

ROBERTS ELECTRONICS INC.

LOS ANGELES 16 - CALIFORNIA

O_.

EXCELLENCE IN ELECTRONICS

ROBERTS SERVICE

'QQOLODELQQQT MANUAL

4 TRACK STEREO
TAPE RECORDERS

Page 2

GENERAL INFORMATION

The Roberts Models 990 and 997 are tour-track
stereo tape recorders which will record and playback
four-track stereo, and four-track monaural tapes.
They will also playback two-track stereo tapes.

Both models operate at tape speeds of 15, 7 1/2,
and 3 3/4 ips with equalization provided.

The Model 997 also provides for sound-with-
sound recording, and a stereo output speaker control
panel with si:: stereo output jacks.

Operate the recorders from a 110-120 volt AC,
60 cycle source only. A conversion kit (Part No. 51-
93) is available for 50 cycle operation.

SPECIFICATIONS

FREQUBICY RESPONSE:

40 to 15,000 cps @ 7 1/2 ips, :l: 2 db;
40 to 12,000 cps @ 3 3/4 ips, d: 3 db;

SlGNAL-TO-NOISE RATIO:
50 db below record "0" level.

WOW AND FLUTI'ER:
Less than 0.12% rms.

EQUALIZATION:
Record and Playback, based on NAB standards.

REEL SIZE.-
3", 5" or 7"

FUNCTION OF CONTROLS

A - Play Record

This is a three-position control. When this con-
trol is straight up, it is in Neutral position; turning
to the right places it in Play and Record positions,
respectively. To prevent accidental erasure, the Re-
cord Interlock button must be depressed before the
bar knob can be moved into the Record position. This
control is mechanically interlocked with the Rewind-
Forward control. The Rewind-Forward control must
be in its Neutral position beforethe Play-Record con-
trol can be placed in either mode.

B - Rewind-Forward

This is athree-position control. When this con-
trol is straight up, it is in Neutral position. Turning
the bar type control knob clockwise places it in the
Forward position, which transfers the tape rapidly
from supply reel to take-up reel. Turning the control
counterclockwise places it in the Rewind position, which
transfersthe tape rapidly from take-up reel to supply
reel. This control is mechanically interlocked with
the Play-Record control. The Play-Record control
must bein Neutral position before turning the Rewind-
Forward control.

C - Stop Lever

The recorder may be stopped momentarily by
pushing upward on the Stop lever. This lever removes
the pressure roller from the capstan, and stops the
tape. The Stoplever maybe released by slightly pres-
singinwardon the lever. Depressing the Start button,
locatedon extreme right of recorder, will also release
the Stop lever.

The Stop lever and Start button function only in
the Play-Record modes of operation.

D - Record Lock

Depressing the Record Interlock button while
placing the Play-Record control in the Record posi-
tion places the recorder in the Record position.

E - Speed Change Lever

The Speed Change lever is located between the
two tape reels. Move lever to right and pull up for
7 l/Zipa. Moveleverto right and push down for 3 3/4
ips. A capstan bushing is used for changing the re-
corder speed to 15ips. The capstan bushing is stored,
when notin use, on a mounting post located next to the
program counter set knob. Remove capstan bushing,
by turning the thumb screw counterclockwise. Place
bushing over capstan and tighten the thumb screw se-
curely with the fingers only. Move the Speed Change
lever to the right and pull up for a tape speed of 15
ips. Move the Speed Change lever to the right and
push down for 7 1/2 ips.

NOTE: The Speed Change lever should be moved

only when transport drive motor is run-
ning.

F - Left Channel Volume

Regulates the Left channel record level when
recording and the volume when playing back a stereo
tape or monaural tape.

G - Left Channel Tone

Controls Bass and Treble response on the Left
channel during playback only.

H - Right Channel Volume

Regulates the Right channel record level when
recording and volume when playing back a stereo tape.

I - Right Channel Tone

Controls Bass and Treble response on the Right
channel during playback only.
J - Equalization Control

Each channel contains an equalization switch to
compensate for tape speeds. These controls should be
placedinthe position corresponding to the tape speed.