Electrical
checksand
adjustments
General
- 0 dB level is defined as:
0.775 V in the RADIO socket, using Ty'pe I or II
tapes.
1.2 V in the RADIO socket usingMetal tape.
1.5 V in the OUTPUT socketsusingType I or II
tapes.
2.3 V in the OUTPUT socketsusing Metal tape.
- Before adjusting, the tape path must be cleaned
and demagnetized.It is necessary
that the tape
path is correctly adjusted.
- Carry out the adjustments in the order described
because the adjustments affect each other.
- Remove the basepanel.
- When adjusting the Bias-traps
and the Bias-pre-
adjustment, the top panel must be removed.
Equipment required
- 2 millivoltmeters
- Audio signal
generator
- Frequency counter
- Distortion meter
- Wow and flutter meter
- Tandberg test cassettes:
- No. 21 (Speedcheck, 1000 Hz)
- No. 22 (Wow and flutter check, 3150 Hz)
- No. 23 (Azimuth adj. playb. head, 6300 Hz)
- No. 24 (Playback level adj., 1000 Hz)
- Measuringcassettes:
- Maxell UD XL I (Type I)
- Maxell UD XL II (Type II)
- Fuji Metal or TDK Metal MA (Metal)
Before adjusting, set buttons to:
- MPX-FILTER (situated at the back of the deck)
to OFF.
- Dolby NR.* to Off.
- Output Lcvel
controls
* The words "Dolby" isregistreredtrademarh of
Dolby Laboratories
Inc., US.Nfi stands
for
Noise
Reduction.
Before
adjusting,fold out page
5.
Oscillator
The oscillator
frequency
is between
80 and 100
kHz. The voltage
measured
on the erasehead
should
be
between6 and8volts
with TypeII or
Metal
cassettes.
Biastraps
- Remove the top panel.
- Nleasurewith a millivoltmeter on C107 and
C207 and adjust L101 and L201 to minimum
reading on the millivoltmeter.
Record/Playback head - azimuth
- Insert a Tandberg test cassette
No. 23 or a
standard azimuth cassette.
- Set the Monitor button to Taoe and connect a
millivoltmeter to eachchannel of the OTITPUT
sockets.
- Pressthe Play button. Adjust the playback
azimuth screw shown in the figure to obtain
maximum reading on eachchannel.
to maximum.
Playback
level
- Insert
Tandberg
test
cassette
No. 24 (Playback
level
adjustment
1000Hz).
- Adjust with the PLAYBACK LEVEL ADJ.
R317/R417
to 1.5V on the
OUTPUTsockets.
(In the RADIO socket,adjustto 775 mV.)
- If you useaDolby level
cassette,
adjust
to 1.2V
on the OUTPUT sockets
(0.615mV in the
RADIO socket).
Bias
(pre-adjustment)
- Set
theTCD 420Ato record,Metal
tape
loaded.
- Adjust with R21031IJ.2203
(Bias
Adjustment
Metal)
to approximately
8 - 9 mV measured
on
TPl andTP2 (on the Osc.
board),seefigure.
