Service notes (continued)
IMPORTANT: To protect against possible damagePrtepoaration
the solid state devices due to arcing or static dis1. charCongenec,t receiver to AC 120 Volts. Do not turn ON.
make certain that all ground wires are sec2.ureConlynect HIGH VOLTAGE meter to 2nd anode
connected.(H.V. button).
Note: Use cold ground() for negative lead.
CAUTION: The power supply circuit is above earth
3.Connect the ammeter serial from the flyback anode
ground and the chassis cannot be polarized. Use an
leadto the picture tube anode socket.
isolation transformer when servicing the receiverto
4. Prepare HHS jig to be connected between TPD50
avoid damage to the test equipment or to the chassis.
and TPD51 as shown in Fig. 2.
Connect the test equipment to the proper ground ( ) or
( ) when servicing, or incorrect voltages Pwrilocledurbee:
measured.
1. Open connector A17.
WARNING: This receiver has been designed to mee2.tTurn power ON and apply a white pattern.
or exceed applicable safety and x-ray radiation
3. Set current within 50mA- 100by changing the
protection as specified by government agencies and
picture and bright controls.
independent testing laboratories.
4. Turn power OFF.
To maintain original product safety design standards
5. Connect HHS jig betweenTPD50 and TPD51 (VR
relative to x-ray radiation and shock and fire haszahoulrd,d be turn fully clockwise).
parts indicated with the symbolon the schema6. ticTurn power on.
must be replaced with identical parts. Order par7.ts Tfurronmslowly the variable resistor to increase the
the manufacturer?s parts center using the pacrutrsrent until the horizontal sync frequency abruptly
numbers shown in this service manual, or provide thinecreases indicating that the horizontal frequency is
chassis number and the part reference number.just beginning to pull out of sync. Maintain the
current with 50-in 100mA by changing the picture
For optimum performance and reliability, all other parts
and bright controls
should be replaced with components of identical
8. Observe the high voltage mHIGHeter.VOLTAGE
specification.
should read less t36khanV.
Horizontal oscillator disable circuit9. Turn power OFF, remove HHS jig, HV meter,
ammeter and connect A17 connector.
This chassis employs a special circuit to protect
10. TurnpowerON.ResetPICTUREand
against excessive high voltage and beam current. If, for
BRIGHTNESS controls. ConfirB+m 140V?1.5V
any reason, the high voltage and beam current exceewitdh 120V AC applied.
a predetermined level this protective circuit activates
and detunes the horizontal oscillator that limits the high
voltage. The over-voltage protection circuit is not
Note: If high voltage is not within the specified
adjustable. However, if components indicated by thelimit, the cause must be determined before
symbolon the schematic in either the horizontalthe receiver is returned to the owner.
sweep system or the over-voltage protection circuit
itself are changed, the operation of the circuit should be
checked using the following procedure:
Equipment needed to check the disabled circuit:
1. DC ammeter
2. High voltage meter (0- 50kV electrostatic)
3. Variac or isolation transformer
4. HHS jig (see Fig. 2)
100W1KW
TPD50TPD51
Figure 2.HHS jig
-6 - |
ACEC
