Samsung UN J5500AF Series Service Manual page 113

UN40J5500FXZA SMPS: Backlight (wired in series)
CM803
Wired at SMPS in Series. If one LED string goes out all are out, no backlight.
3 LED Strings 3
- + -
Control
LED Min
Pins B/L
3- 130Vdc
3+ 174Vdc 151Vdc
2- 174Vdc 151Vdc
2+ 218Vdc 207Vdc
1- 218Vdc 207Vdc
1+ 241Vdc 235Vdc
2 1
+ - +
Fixed Supply
Max Full B/L
B/L Test
95Vdc 88Vdc
144Vdc
144Vdc
200Vdc
200Vdc
230Vdc
CNL802
Panel Con. Sample
Removed 2- open
0 0
0 0
0 Opened
0 257Vdc
0 257Vdc
275Vdc 279Vdc
230Vdc (panel size dependent)
BL Supply measured at diode Stripe
(cathode). This will raise to approx
280Vdc with an open string of LEDs.
CNL802 (to BLU)
1 NC 9
2 3 + 10
3 3 - 11
4 NC 12
5 NC 13
6 2 + 14
7 2 - 15
8 NC 16
Simplified BACKLIGHTS Tes
1. Activate Backlights – Disconnect
Cable from Main to Power Supply.
2. Measure BL Supply voltage at
the supply diode cathode (stripe).
3. Remove Panel connector and
measure again to compare.
4. If voltage is high and stays the same
high reading a string of Panel LEDs are open.
Replace the Panel.
If the voltage is low and remains low
SMPS is defective.
NC
1 +
1 -
NC
NC
NC
IF2
IF1
t
Lead
1+ or at
the