Standard value: 0.28V [0.40+0.05V: at LINE OUT jack]
Adjustment
1. If the measured value is not within standard the adjust VR5 (L-CH) or VR6 (R-CH) (See fig. 1).
2. After adjustment, check "Playback frequency response" again.
|
@ Erase current
Condition:
Equipment:
e Record mode
eVTVM
¢ Metal tape mode
* Oscilloscope
. Test equipment connection is shown in fig. 9.
Erase head
. Place UNIT into metal tape mode.
. Press the record and pause buttons.
. Read voltage on VTVM and calculate erase current by following formula:
Voltage across resistor R73
1 (8)
Standard value: 155+15mA (Metal)
. {f the measured value is not within the standard value adjust it by following
the adjustment instructions.
Erase current (A) =
VIVM
Oscilloscape
Adjustment
If the erase current is more than 170mA, cut the jumper wire (See fig. 1).
(@ Overall frequency
Condition:
Equipment:
response
e Record/playback mode
eVTVM
e Test tape
¢ Normal tape mode
© ATT
(reference blank tape)
e CrO, tape mode
e AF oscillator
...QZZCRA for Normal
¢ Metal tape mode
¢ Oscilloscope
...QZZCRX for CrO,
¢ Input level controls...
MAX
e Resistor (6002)
...QZZCRZ for Metal
e Balance control...Center
VR7 (L-CH)
Note
VRB (R-CH)
5008
Before measuring and adjusting, the overall frequency response make
(
LINE IN
;
sure of the playback frequency response (For the method of measure-
ce ale
:
|
ment, please refer to the playback frequency response).
ee
TP1 (L-CH}
;
ee
TP2 (R-CH
q
(Recording equalizer is fixed)
eee ts
1. Make connections as shown in fig. 10.
VR18 (R-CH)
. Place UNIT into normal tape mode and insert the normal reference
blank test tape (QZZCRA).
5OMEh
. Pe
a 1kHz signal from the AF oscillator through ATT to LINE
VIVM Oscilloscope
IN.
For bias
current"
. Adjust ATT so that input level is -20dB below standard recording
measurement
level (standard recording level = 0 VU).
Fig. 10
. Adjust the AF oscillator frequency to 1kHz, 50Hz, 100Hz, 200 Hz,
500 Hz, 4kHz, 8kHz, 10kKHz and 12.5kHz signals, and record these
signals on the test tape.
Overall frequency response chart (Normal)
. Playback the signals recorded in step 6, and check if the frequen-
cy response curve is within the limits shown in the overall frequen- |
cy response chart for normal tapes (fig. 11).
(if the curve is within the charted specifications, proceed to steps
7, 8 and 9.)
lf the curve is not within the charted specifications, adjust as
follows;
VTVM
Oscilloscope
For overall frequency
response measurement
50Hz
100Hz
200Hz
500Hz
1kHz
6kHz
12.5kHz
10kHz
Fig. 11
Adjustment (A):
Adjustment (B):
When
the curve
exceeds
the
-———+
When the curve falis below the
overall
specified
frequency
overall
specified
frequency
response
chart
(fig.
11)
as f
response
chart
(fig.
11)
as >
shown in fig. 12.
<i
shown in fig. 13.
1) Increase
bias
current
b
|
a
ie
1) Reduce
bias
current
by
turning VR7 (L-CH) and VR
=
+H
turning VR7 (L-CH) and VR8
(R-CH).
ona
(R-CH).
(See fig. 1 on page
5.)
2kHz
6kHz
{ 12.5kHz
1kHz
2kHz
