Onkyo TX-SR502 Reference manual

SERVICE BULLETIN
NO:04003
2004/04/21
MODELS : TX-SR502/502E/8250/HT-R520
SUBJECT : The countermeasure against IC oscillation.
Symptom:
TX-SR502's output sometimes has a hum with signals after power on within
few minutes.
When selector or DSP mode is switched to another at this moment, the protect
program starts.
Cause:
Oscillatation of IC regulator.
Procedure for service:
To exchange an electrolytic capacitor with that of 330uF for C6412 in NADG-
8230.
Circuit No. Before
change After change
Parts No. Description Parts No. Description
C6412 394741007 ELECT C
CE04W16V10M 394743317 ELECT C CE04W16V330M
Marking: No change
Application:
TX-SR502(B) MDD, MDC
HT-R520(B) MDD, MDC #1-
HT-R520(S) MDD, MDC #1-

TX-SR502
SERVICE BULLETIN No.04003
The countermeasure against IC oscillation.
bend
cut
hook
IN
OUT
heat sink
1
Electrolytic Capacitor
330uF 16V
394743317
2
3
4
Q6406
IN
OUT
heat sink
C6412 remove
solder
solder
fix with bond
5
side
Front
Preamplifier PC board
NADG-8230
side
heat sink
GND
TOP VIEW
TOP VIEW
8
7
6
Q6406
heat sink
disconnect
P7502
P7502
P7502
connect
9
Visual Check
1. Check if the capacitor is properly connected to the
IC considering polarity.
2. Check if soldering was done by using just enough
quantity of solder and heat and there remains enough
clearance between the capacitor and the other
terminals or heat sink nearby.
3. Check if just enough bond is used to fix the capacitor
and no bond is left around socket.
4. Check if FFC of P7502B is inserted in the socket in the
right direction from the right angle.
Operation Check
Check if sound outputs properly when digital sound signal
is input.