Technics RS-M10 - Page 7

Bias current
Equipment:
*VTVM
* Oscilloscope
Erase current
Equipment:
*VTVM
* Oscilloscope
* Resistor (12)
MEASUREMENT & ADJUSTMENT
1. Test equipment connection is shown below.
TPL(L-CH)
Record
mode
TP2{R-CH)
RuL-CH)
VTVM Oscilloscope
Fig. 15
. Place UNIT into record mode, and bias selector to “LOW”.
. Read voltage on VTVM and calculate bias current by following for-
mula:
_Value read on VTVM (V)
Bias current (A) = -— 10 (0) maze
Standard value:
285A (Normal position)
340A (FeCr position)
| 380A (Cr02 position)
. Adjust L5 (L-CH) and L6 (R-CH) (See adjustment parts location on
page 10).
. Connect 12 resistor between the ground side terminal of erase head
ground lead wire removed (See fig. 17).
. Connect VTVM to both ends of 1Q resistor.
Erase head
Fig. 16
3. Place UNIT into record mode, and measure voltage across the 1Q
resistor,
4. Determine erase current with the following formula:
Voitage across both ends of 1Q resistor
12
Erase current (A) =
Standard value:
More than 40mA (Normal position)
More than 45mA (FeCr position) _
More than 55mA (Cr0Qz position)
REMARKS
* Record mode
* When bias current is the
adjusted on one channel
only, note that bias current
on the other channel may
vary.
* When L5 or L6 ts the
replaced, preset core
position to bottom side of
coil and then readjust
optimum bias current.
* Record mode
Erase head