Pulse Power Supply Board Repairing; Inverter Circuit Transistor Replacement; Inverter Circuit Transformer Replacement - Sony TA-AX5 Service Manual

1 . 2 . S E R V I C I N G N O T E
1. Pulse Power Supply Board Repairing
This set has a pulse power-supply circuit which
is quite
different
from
a conventional power-
supply circuit.
The pulse power-supply directly
rectifies and smooths the ac input power to
produce the higher dc voltages required in the
power-supply circuit. When servicing this set, note
the following.
a) To prevent urrwanted radiation due to pulse
signals in the pulse power-supply circuit, the
pulse power-supply board is shielded by the
aluminum diecast box.
b) Take care that electrolytic capactitor which is
used after the rectification of ac power source
voltage is charged even if the POWER switch is
turned off. Be sure to use a resistor of at least
several hundred ohms to discharge the capaci-
tor. Direct discharge by means of lead is
dangerous.
2. Inverter Circuit Transistor Replacement
When any of inverter transistors (Q903, Q904)
is broken, replace their transistors together. A pair
of transistors with the same rank is provided for
service field use.
Rsf. No. Pert No.
Description
Q903, Q904
x-4866-605-l
Transistor Ass'y, seryice
3. Inverter Circuit Transformer Replacement
The lead wire arrangement for each of T90l
and T9O2 in the inverter circuit is shown in Fig. A.
As the repair parts, T90l and T9O2 arc formed
by only iron core. Thus, if the coil is defective,
arange a new transforners as shown below. Note
that the lead lengths must be exact. Also wind the
coil carefully.
T90l core lPart No. l-543-098-001
\ l-543-tOO-OO1
7902 core (Part No. l-543-166-00)
( one turn
I wire length: 70 mm (2% inches)
I diameter : UL 106l AWG28
I two tums
I wirc length: 70 mm (2% inches)
ldiameter : UL lMl AWG28
I two turns
I wire length : 55 mm (21/6inchesl
I diameter- : UL t6l
AWG2B
40 mm ( | 3Â inches)
UL I4:'O AWG22
two tums.
wire length: 70 mm (2i4 inchas)
diameter : UL 106l AWG28
FtC. A