Section 2: Safety Related Adjustments; Hv Regulator Circuit Check; Hv Protector Circuit Check; Beam Current Protector Circuit Check - HP P4819 Service Manual

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.
HV ADJ
D Board C925, IC901, R901, R902, R905,
HV Regulator
Circuit Check
HV HOLD
D Board C920, C923, D911, D912, R903,
DOWN
Circuit Check
N Board IC1001, RB1001
D Board C930, D917, R921, R932, R933,
Beam Current
Protector
Circuit Check
N Board IC1001, RB1001
Confirm one minute after turning on the power.

SECTION 2: SAFETY RELATED ADJUSTMENTS

Part Replaced ( )
RV901
Part Replaced ( )
R924, R925, R926, RV901,
T901 (FBT),
• Mounted D Board
R917, R918, R919, R920, R923,
T901 (FBT)
• Mounted D Board
• Mounted N Board
R935, T901 (FBT)
• Mounted D Board
• Mounted N Board

2-1. HV REGULATOR CIRCUIT CHECK

1. Turn the RV901 slowly, and adjust so that high voltage is in the
specified range.
[Specification]: 27.00 ± 0.05 kV
2. Check that the voltage of D912 cathode on the D board is 17.0V
or more.

2-2. HV PROTECTOR CIRCUIT CHECK

1. Using external DC Power Supply, apply the voltage shown below
between cathode of D912 and GND, and check that the RASTER
disappears.
[Specification]: 19.95 ± 0.00/-0.05V
2-3. BEAM CURRENT PROTECTOR CIRCUIT
CHECK
1. Connect constant current source to a section between T901 (FBT)
11
pin and GND, and check that the RASTER disappears when
the specified current flows to the
[Specification]: 2.12 ± 0.00/-0.051 mA
— 15 —
11
pin.
P4819