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MCM-19T1
When replacing parts shown in the table below, the following
operational checks must be performed as a safety precaution
against X-ray emissions from the unit.
Part Replaced (
Part Replaced (
T901, R903, IC805, R921, R922, R812, D908, IC605,
R913, R914, D802, D909
Allow the unit to warm up for one minute prior to checking
the following conditions:
HV Regulator Check
1)
Input white cross hatch signal. (fH = 94 kHz)
2)
Minimum CONT and BRT controls.
3)
Cut off Screen VR (G2).
4)
Input voltage: 120 ± 2 VAC
5)
Confirm that the voltage is within the voltage range
shown below.
Standard voltage: 27.0KV ± 0.2KV
6)
When replacing components identified by
sure to recheck the High Voltage.
7)
Verify the High Voltage as shown above (27.0KV
+0.2KV) is within specification. If not, set H. SIZE data
at minimum (-127) and then adjust RV904 on "D" Board.
8)
After adjusting the High Voltage within specification,
put the RV cover on RV904 as shown below and apply
sufficient amount of RTV around RV904.
SAFETY RELATED ADJUSTMENT
D - BOARD
)
RV904
)
, make
RV904
SECTION 3
HV Hold-Down Check
1)
Using an external DC Power supply, apply the
voltage shown below between cathode of D908 on
"D" Board and GND, and confirm that the HV Hold-
Down circuit works. (Raster disappears)
Apply DC Voltage: 21.5 ± 0.5 VDC
Check Condition
• Input voltage : 120 ± 2 VAC
• Input signal : (fH = 94 kHz), White Cross Hatch
• Controls : CONT (max) & BRT (center)
•B+ Voltage: 181 ± 4.0 VDC
Beam Protector Check (Software logic)
1) Using an external current source, apply 1.30 ± 0.05 mA
between pin 11 of FBT (T501) and GND, and
confirm that the voltage at CN801 pin 1 is 2.25
VDC or less.
Check Condition
• Input voltage : 120 ± 2 VAC
• Input signal : (fH = 94 kHz), White Cross Hatch
• Controls: CONT (max) & BRT (center)
B± Maximum Check
1)
Input white cross hatch (fH = 94 kHz) signal.
2)
CONT (max) & BRT (center)
3)
Input voltage: 120 ± 2 VAC
Note: Use NF power supply or make sure that
4)
Confirm that the voltage is within the voltage range
shown below.
— 12 —
distortion factor is 3% or less.
Standard voltage: 181 ± 4.0 VDC
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