45
The procedure is as follows:
1. Replace RV8001, RV8002, and RV8003 (they are epoxyed).
2. Turn RV8001 and RV8003 both CCW from the top of the D board.
3. Turn the set ON with a black screen (HV unloaded).
4. Adjust HV RV8002 for 35.5kV (shutdown threshold).
5. Adjust RV8001 and RV8003 until the set just shuts down.
6. Turn HV RV8002 CW to turn the set ON. Input a white signal. Bring
the HV up to 35kV to make sure the set does not shut down. (This
rechecks the RV8001 and RV8003 adjustments.)
7. Adjust HV RV8002 for 31.5kV.
8. Guard against premature shutdown by following bulletin 492
(appendix).
Testing
1. HV Check - Measuring the voltage at D8025/Cathode verifies HV.
Normally D8025/Cathode = 31.6Vdc when there is HV, and 0V when HV
is missing. D8025’s Anode voltage should not be higher than 0.6Vdc in
normal operation (measured). D8025 is located next to the potted (epoxy
sealed) RV8001/RV8003 controls at the left edge of the D board.
2. HV Converter Check - If no HV is output, look for +200V input at
IC8002/pin 18 and more than 15.6V at IC8002/pin 8.
Look for HV Conv start voltage at IC8002/pin 1 (normally 1.6Vdc but must
be more than 1.3Vdc. to start).
Converter IC8002 Voltages
Pin
1
2
3
4
5
6
7
8
9
Volts
1.63
1.75
2.25
2.47
0
0
4.56
14.7
0
Pin
10
11
12
13
14
15
16
17
18
Volts
10.3
0
4.14
0
108
98.6
103
0
200
Additional Important Voltages related to IC8002/pin 1 Voltage
Electrical Location
Physical Location
Voltage
IC8001/pin 1
0V
IC8001/pin 2
14 pin Surface mounted IC under
RV8001/RV8003
0V
C8004/ + lead
Behind IC5515 s large heat sink
next to large 820uf, 250V C8023.
0.02V
3. HV may be starting, then shutting down - Monitor D8025/Cathode for
3.16V at start up. If it is 0V, there is no HV. Check the converter transis-
tors and suspect IC8002 and the flyback to cause OCP shutdown (via
Q8009). If the cathold voltage momentarily rises to beyond 31Vdc, there
is HV but it may be excessive. Turn the RV8001 and RV8003 controls
CCW and adjust the HV. Follow the HV adjustment procedure. If shut-
down still occurs suspect D8025, C8005, and D8004.
D Bd
A Bd
KV32XBR400 rear
D8025
Flyback
Содержание KV-32XBR400
Страница 1: ......
Страница 5: ...1 NOTES ...
Страница 12: ...8 NOTES ...
Страница 14: ...10 NOTES ...
Страница 83: ...APPENDIX ...