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RA-5A Chassis D Board Tests
RA-5A Chassis D Board Tests
Many voltages from the G board are delivered to the D board (CN8013 in Figure 24-1) for deflection use. The
135V path continues into the A and V boards. A short on the D board will load down the power supply, but the D
board can be quickly tested for shorts.
G
board
D board
A board
Vr board
Vg board
Vb board
CN8013
CN8006
+135V
CN8013
Figure 24-1
-135V Distribution
This D board can be tested for excessive current demand (shorts) either by making resistance (ohms) checks or
by supplying voltage to each input of CN8013 to see if it is normal. The conditions are that the D board is
unplugged from the TV before resistance measurements are taken and the polarity of the ohmmeter voltage
matches that of the load. The DVM used was a Fluke 8050A set to 200k ohm range. Your ohmmeter will show
different readings but they will be proportional.
The DVM leads were reversed so the – voltage from the DVM was applied to the –22 and –15 volt pins of
CN8013/pins 1 and 4. By maintaining the correct polarity, premature parts failures can be avoided. See Chart 24-
1.
Chart 24-1 - D Board Excessive Current Demand Tests
Input
Name
Location
Ohms to Gnd
(charging caps)
Current
Destination
Major Part
+135V
CN8013/pin 9
1.2k to 55k in 1 min.
0.5A at 30Vdc
HV Conv.,
PS for HV Conv,
H Out,
PS for H Out,
A board
Q8038,
Q8035,
Q8024,
Q8027,
CN8006/10
+22Vdc CN8013/pin 6
4k to infinity
0.02ma at 22Vdc
-22Vdc
CN8013/pin 4
1.7k to 7k
9.29ma at –22Vdc
STK Convergence Amp,
Dynamic Focus
IC8001, 2;
Q8008, 9
+15Vdc CN8013/pin 3
800 to 10.5k in 1 min
110.7ma at 15Vdc
-15Vdc
CN8013/pin 1
1k to 65k in 1 min.
5.09ma at –15Vdc
Vertical Output
H Drive
IC8003,
Q8036, 7
Содержание KD-34XBR2 - 34" Hdtv Fd Trinitron Wega
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