Dell D825TM Service Manual - Page 12
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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.
D - BOARD
Part Replaced ([)
RV501
Part Replaced (])
RV501, T501, R545, R546, R548, R550, R547, R549, R552,
D517, IC605, IC901, C540, C542, C544, C541, C535,
IC501, C558, R567, R564, C555, C553, C554, C561
Allow the unit to warm up for one minute prior to
checking the following conditions:
a
) HV Regulator Check
1) Input white cross hatch signal. (fH = 64 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: 25.0KV + 0.5KV
6) When replacing components identified by ], make
sure to recheck the High Voltage.
7) Verify the High Voltage as shown above (25.0KV + 0.5KV)
is within specification.
minimum (-127) and then adjust RV501 on "D" Board.
8) After adjusting the High Voltage within specification,
put the RV cover on RV501 as shown below and apply
sufficient amount of RTV around RV501.
SECTION 3
SAFETY RELATED ADJUSTMENT
If not, set H. SIZE data at
R V 5 0 1
— 12 —
b) HV Hold-Down Check
1) Using an external DC Power supply, apply the
voltage shown below between cathode of D517
o n
" D " Board and GND, and confirm that the
HV Hold-Down circuit works. (Raster disappears)
Apply DC Voltage: 31.4 + 0.01 VDC
Check Condition
• Input voltage : 120 + 2 VAC
• Input signal
: (fH = 64 kHz), White Cross Hatch
• Controls
: CONT (max) & BRT (center)
• B+ Voltage
: 144 + 3.0 VDC
c) Beam Protector Check (Software logic)
1) Using an external DC power supply, apply the
voltage
8.8 + 0.01 VDC between pin
(T501) and GND, and confirm that the voltage
across C541 is 3.7 VDC or less.
Check Condition
• Input voltage : 120 + 2 VAC
• Input signal
: (fH = 64 kHz), White Cross Hatch
• Controls
: CONT (max) & BRT (center)
d) B+ MAX. Check
1) Input white cross hatch (fH = 64 kHz) signal.
2) CONT (max) & BRT (center)
3) Input voltage: 120 + 2 VAC
Note: Use NF power supply or make sure that
distortion factor is 3% or less.
4) Confirm that the voltage is within the voltage
range shown below.
Standard voltage: 144 + 3.0 VDC
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