Circuit Protective Elements; Unleaded Solder - Sony RM-B750 User Manual

1-10. Note on Service
Controls, Rotary Encoder
Turn the controls from 01 to 15 in the following table in
order, and check that the followings are satisfied using
Diag Mode 1.
. When turning the control knob, the appropriate VR No.
of this control knob is displayed at the bottom right on
the LCD. Also the adjustment value is displayed in the
appropriate box on the LCD.
(The display position of the VR No is assigned in order
of VR No. 01 and 02 from the upper left on the LCD.)
. The variable range of the adjustment value which is
displayed by turning the control knob is coincide with the
value of the adjustable range column in the following table.
* * * * * When turning the WHITE-R control knob (VR No. 5)
Diag Mode 1
0
LCD
VR No. Adjustment controls
*1
01 Rotary encoder 1
*1
02 Rotary encoder 2
03 Rotary encoder 3 *1
04 Rotary encoder 4 *1
05 WHITE-R
06 _
07 WHITE-B
08 _
09 BLACK-R
_
10
11 BLACK-B
12 MASTER BLACK control
13 IRIS control
14 _
15 _
*1: The rotary encoder 1 is the left most of the control knob.
4. Press the PANEL ACTIVE and STANDARD buttons
simultaneously to leave the menu.
1-14 (E)
Adjustment value
5
VR No.
Adjustable range
_99 to +99
_90 (or less) to
+90 (or more)

1-10-9. Circuit Protective Elements

The positive characteristic thermistor (for power supply)
functions as a circuit protective element on the VR-277
board (B side) of the unit shown below. The thermistor
increases the internal resistance and limits the current
flowing to the circuits when an overcurrent flows or when
the ambient temperature increases and the element reaches
the specified temperature.If the elements operates,turn off
the main power and inspect the RM-B750 internal
circuit.After removing the cause of the equipment abnor-
mality and the temperature of the element decreases,turn
on the power again and operare the unit correctly.It takes
about 1 minute for the elements to cool down after the
main power is turned off.
Borad Ref.No. Address Protective circuit/equipment
VR-277 THP203 C-2
THP205 B-2

1-10-10. Unleaded Solder

Boards requiring use of unleaded solder are printed with a
lead free mark (LF) indicating the solder contains no lead.
(Caution: Some printed circuit boards may not come
printed with the lead free mark due to their particular size.)
: LEAD FREE MARK
m
. Be sure to use the unleaded solder for the printed circuit
board printed with the lead free mark.
. The unleaded solder melts at a temperature about 40 dC
higher than the ordinary solder, therefore, it is recom-
mended to use the soldering iron having a temperature
regulator.
. The ordinary soldering iron can be used but the iron tip
has to be applied to the solder joint for a slightly longer
time. The printed pattern (copper foil) may peel away if
the heated tip is applied for too long, so be careful.
Circuit inside the board
RM-B750