LG 42PG20 Training Manual page 39

Y-DRIvE bUFFER TROUblEShOOTING
Using the "Diode Test" on the DVM, check the pins for shorts or abnormal loads. You
can check all 8 buffer ICs using this procedure. Using the "Diode Test" on a digital volt
meter, check the pins for shorts or abnormal loads. Any of the output lugs can be tested.
Look for shorts indicating a defective Buffer IC.
BACK SIDE OF Y-DRIVE
A
B
Anywhere
BACK SIDE OF Y-DRIVE PWB
OUTPUT LUGS
CIRCUIT DeSCRIPTIONS
-
BLACK LEAD ON
A
+
RED LEAD ON
A
+
RED LEAD ON
BUFFER IC
Indicated by Red outline
-
BLACK LEAD ON
BUFFER IC
Indicated by Red outline
FORWARD
+
RED LEAD ON "B"
READING 0.73 V
REVERSE
-
BLACK LEAD ON "B"
READING "OPEN"
-
BLACK LEAD ON "ANY"
OUTPUT LUG.
READING 0.73 V
+
RED LEAD ON "ANY"
OUTPUT LUG.
READING "OPEN"
PDP Training - Fall 2008
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