11TV024R1
KDL-32EX421, 25,
KDL-32EX520, 21, 23, 24, 25
KDL-32EX720, 21, 23, 24, 25, 26, 27, 28, 29
KDL-37EX521, 24, 25
KDL-37EX720, 23, 25
Subject: Buzzing Noise / Main Board or PSU Change [REVISION 1]
SYMPTOM
Buzzing noise audible in active standby mode.
CAUSE
Buzzing noise detected in power supply.
SOLUTION
1. Use the improved PSU as indicated in the table below to eliminate the buzzing noise.
Model Original New Part number
KDL-32EX42x
KDL-32EX52x GE2A GE2AR 1-474-357-11
KDL-37EX52x
KDL-32EX72x
G10A G10AV 1-474-358-11
G10B G10BV 1-474-359-11
KDL-37EX72x G10B G10BV 1-474-359-11
2. When you change the BAT-V board or PSU in service, change the register SREG(PFC_EN_DC) as described
below.
PSU SREG(PFC_EN_DC)
GE2A, G10A, G10B 0
GE2AV, GE2AR, G10AV, G10BV
11TV024R4
REACTIVE H144 2 TD
Models
KDL-32EX421, 25,
KDL-32EX520, 21, 23, 24, 25
KDL-32EX720, 21, 23, 24, 25, 26, 27, 28, 29
KDL-37EX521, 24, 25
KDL-37EX720, 23, 25
Subject: Buzzing Noise / Main Board or PSU Change [REVISION 4]
SYMPTOM
Buzzing noise audible in active standby mode.
CAUSE
Wrong SREG setting.
SOLUTION
Depending on the configuration, install an improved PSU and/or change the register SREG(PFC_EN_DC) value.
OPTION A. Old board (refer to table below) => Change PSU + change register value from “0” to “1”.
OLD Board label info NEW Board label info
TV Model
Model Board Part number Model Board Part number
APS-288 GE2A 1-474-277-xx APS-288/B
APS-288/C
GE2AV
GE2AR
1-474-336-xx
1-474-357-xx
KDL-32EX42x
KDL-32EX52x
KDL-37EX52x
APS-290 G10A 1-474-294-xx APS-312 G10AV 1-474-358-11
KDL-32EX72x
APS-302 G10B 1-474-295-xx APS-313 G10BV 1-474-359-11
APS-302 G10B 1-474-295-xx APS-313 G10BV 1-474-359-11 KDL-37EX72x
How to change SREG(PFC_EN_DC) value from “0” to “1”?
1. Enter Service Mode by pressing [Display] => [5] => [Vol+] => [Power ON].
2. Go to VPC SERVICE by pressing [Option] twice.
3. Select “008 POWER” by pushing [2] 8 times or [5] once and check “PFC_EN_DC” = “0”.
4. Change “PFC_EN_DC” = “1” by pushing the “3” key once.
5. Execute service save by pushing “Mute” => “0” key. ‘WRITE’ appears on the screen. Do NOT power off!
