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2-1 NISSHIN-CHO,NEYAGAWA-SHI,OSAKA 572-8540,JAPAN
Techinical InformationGroup,Service Dept.
SERVICE BULLETIN
NO:99010-r1
LAST REVISED :00/03/02
DATE : 99/09/03 MODELS : TX-DS575
SUBJECT : Noise is heard from "VOLUME MIN" to "VOLUME 1".
Symptom:
When MASTER VOLUME is raised from "VOLUME MIN" to "VOLUME 1", the noise is heard from front
speaker, center speaker, and rear speaker.
Cause:
The gain of the following circuit from master volume is higher, and the residual noise in the amplifier was larger.
Procedure for service:
Please improve the complaint goods without "A" added at the end of serial numbers as follows.
a. The gain of all channels is reduced.
b. Noise decrease
c. Distortion rate improvement
Because the distortion rate worsens by reducing the gain, please do measures of item C.
If the volume position is raised about 30 degrees, the noise becomes as well as before measures when measures
are executed.
The following service improvement ideas have the effect of the improvement of about 7~9dB.
Circuit No. Before After Parts No. Remarks
a. Gain reduce (NAVD-6566)
R3183,R3283 39kohm 18kohm 417341834 Front L/R
R3184,R3284 47kohm 10kohm 417341034 Front L/R
R3384,R3484,R3584 22kohm 6.8kohm 417346824 Center,Surround
R3683 330ohm 820ohm 417348214 Sub-woofer
b. Noise decrease (NAVD-6566)
Q3180,Q3181,Q3281 NJM4558L NJM4580L-D 22240312 Front L/R
C3183,C3185,C3283 27pF 220pF 345022214 >100KHz
C3285,C3383,C3483
C3583
c. Distortion rate improvement
R3199(NAVD-6566) 100kohm 220kohm 417342244 Additional
J231(NAVD-6566) ( 1)
*
J231 10kohm 417341034
R7089(NADIS-6576) ( 2) 220ohm
* 10kohm 433121034R1
NOTE :
* 1 and
* 2 are same mofdification. Please modify
*1 or *2.
KIT NO. : 0T0058