3-7
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Only for training and service purposes.
ONE POINT REPAIR GUIDE
NO BOOTING WHEN YOU TURN THE UNIT ON, NO MESSAGE OR “HELLO”
ON FRONT PANEL
When you turn on your set, it will blank / no message on front panel / doesn’t work.
1-3. IC301 System 3.3 V (No 3.3 VA)
1-3-1. Solution
Replace MAIN board.
1-3-2. How to troubleshoot (Countermeasure)
1) Please check 3.3 VA of IC301 pin3.
2) If 3.3 VA is abnormal, replace MAIN board.
3) If 5.1 VA is OK, replace MAIN board.
1-3-3. Service hint (Any picture / Remark)
< MAIN board top view >
C322
10uF
/10V
C354
10uF
/10V
C309
10uF
/16V
C328
47pF
R356
4.7K
R309
24K
(1%)
R357
100K
(1%)
FB305
5.1VA
3.3VA
DGND
DGNDDGND
C3A4
100nF
IC301
1
EN
2
GND
3
LX
4
VIN
5
FB
R373
0OHM
NC
R304
240K
(1%)
C3A5
100nF
C3A8
100nF
R332
51K
(1%)
C369
100nF
C370
10uF
/16V
L301
470nH
[5.1VA TO 3.3VA]
VOUT = 0.6*(1+R1/(R2//R3))
VOUT = 0.6*(1+100K/((24K*240K)/(24K+240K)))
= 0.6*(1+100K/21.82K) = 3.350V
IC301
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