Backlight Test
CNL802 (to BLU)
1 N.C 9 N.C
2 N.C 10 1+
3 3+ 11 1-
4 N.C 12 N.C
5 N.C 13 N.C
6 2+ 14 2+
7 3- 15 IF2
8 N.C 16 IF1
CNM803
CNL802
230 Vdc(panel size dependent)
BL Supply measure at diode Stripe(cathode).
This will raise to approx 280 Vdc with an open of
LEDs.
<Series Strings of LEDs>
3 Sets of LED Strings in series 3 2 1
LED Pins Min B/L Max B/L Full B/L Test Panel Con. Removed Sample 2-open
3- 130 Vdc 95 Vdc 88 Vdc 0 0
3+ 174 Vdc 151 Vdc 144 Vdc 0 0
2- 174 Vdc 151 Vdc 144 Vdc 0 Opened
2+ 218 Vdc 207 Vdc 200 Vdc 0 257 Vdc
1- 218 Vdc 207 Vdc 200 Vdc 0 257 Vdc
1+ 241 Vdc 235 Vdc 230 Vdc 275 Vdc 276 Vdc
Activate Backlights Test1. :
Disconnect Lead Cable from Main Board to Power Supply.
Measure BL Supply2. :
voltage at 1+ or at the supply diode cathode(stripe).
Remove Panel connector3. :
and measure again to compare.
If voltage is high4. :
and stays the same high reading a string of Panel LEDs are open.
Replace the 9 PANEL.
If the Voltage is low and remains low the SMPS is defective.
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