Safety Related Adjustment - IBM 6550-23N Service Manual

6550-23N/23S/33N/63N/63S/73N
When replacing or repairing the shown below table, the
following operational checks must be performed as a
safety precaution against X-rays emissions from the unit.
HV ADJ
HV Regulator
Circuit Check
HV Protector
Circuit Check
Beam Current
Protector Circuit
Check
* Confirm one minute later turning on the power.

SAFETY RELATED ADJUSTMENT

[
Part Replaced ( )
RV501
]
Part Replaced ( )
D board IC501, C532, C534,
C539, C553, C554,
C555, C556, C558,
C561, R540, R541,
R542, R544, R564,
R567, R568, RV501,
T501 (FBT)
D board IC607, IC901, D515,
D517, C540, C542,
C544, R510, R543
R547, R549, R552,
R595,
T501 (FBT)
D board IC605, IC607, IC901,
C535, C541, R545,
R546, R548, R550,
R596, R934,
T501 (FBT)
SECTION 3
• HV Protector Circuit Check
Using an external DC Power Supply, apply the voltage
shown below between cathode of D517 on D board and
GND, and confirm that the HV HOLD DOWN circuite
works. (TV Rester disappears)
Standard voltage : 35.80
Check Condition
• Input voltage : 120 ± 2 V AC
• Input signal
• Beam control : CONT : 0 (min), BRT : 0 (min)
• Beam Current Protector Check
An ammeter in series between FBT pin !] on D board
and GND, then, decrease gradually the resistance of the
variable resistor from maximum to minimum, and con-
firm that the Beam Current Protector Circuite works
(TV Rester disappears). The current must be within the
range shown below.
• Standard current : 1.55
Check Condition
• Input voltage : 120 ± 2 V AC
• Input signal
• Beam control : CONT : 0 (min), BRT : 0 (min)
• B+ Voltage Check
Standard voltage : 179.0 ± 3.0 V DC
Check Condition
• Input voltage : 120 V AC
Note : Use NF power supply or make sure that
distortion factor is 3% or less.
• Input signal
• Beam control : CONT : 255 (max), BRT : 255 (max)
3-1
+0.00
V DC
-0.10
: Cross hatch (White lines on Black
back ground) at 68.7kHz / 85Hz
(Mode 7)
+0.00 mA
-0.10
: Cross hatch (Black lines on white) at
31.5kHz / 60Hz (Mode 1)
: Cross hatch (White lines on black) at
68.7 kHz / 85Hz (Mode 7)