Technics RS-630USD

Bias current
Equipment:
* VTVM
* Oscilloscope
Erase current
Equipment:
* VTVM
* Oscilloscope
* Resistor (1)
MEASUREMENT & ADJUSTMENT
1. Test equipment connection is shown below.
Record mode
R1 (L-CH)
VTVM Oscilloscope
Fig. 16
. Place UNIT into record mode, and tape selector to “NORMAL.” (for
normal tape).
. Read voltage on VTVM and calculate bias current by following for-
mula:
Value read on VTVM (V)
10 (Q)
Bias current (A) =
Standard Value: 0.17+0.15mA
. Adjust L5 (L-CH), and L6 (R-CH) (See adjustment part location on
page 14).
. Then changing the equalizer selector to 7OuS and bias selector to
HIGH (for CrOz tape), confirn that bias current become greater by 25%
than that for normal.
. Connect 12 resistor between ground side terminal of erase head
and ground lead wire removed (See fig. 18).
. Connect VTVM to both ends of 1 resistor.
Erase head
VTVM Oscilloscope
Fig. 17
3. Place UNIT into record mode and, measure voltage across the 12
resistor.
4. Determine erase current with the following formula:
Voltage across 1Q resistor (V)
1(Q)
Erase current (A) =
Standard Value: More than 70mA
REMARKS
* Record mode
+ Be sure the ground end
of the meter is connected
to the ground end of the
resistor.
+ When bias current is
adjusted on one channel
only, note that bias
current on the other
channel may vary.
+ Record mode
Erase head
BLACK
Fig. 18