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 Test
1.
:
Disconnect Lead Cable from Main Board to Power Supply.
Measure BL Supply
2.
:
voltage at 1+ or at the supply diode cathode(stripe).
Remove Panel connector
3.
:
and measure again to compare.
If voltage is high
4.
:
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.
4-11
4. Troubleshooting
