CIRCUIT CHECKS
SPECIFIC INFORMATIONS GENERAL ADJUSTMENTS
HIGH VOLTAGE CHECK
CAUTION: There is no HIGH VOLTAGE ADJUSTMENT on this chassis. Checking should be done following the steps below.
1.Connect an accurate high voltage meter to the anode of the picture tube.
2.Turn on the receiver. Set the BRIGHTNESS and CON- TRAST to minimum (zero beam current).
3.High voltage must be measured below (B) kV.
Refer to
(See SETTING & ADJUSTING DATA on page 17)
4.Vary the BRIGHTNESS to both extremes to be sure the high voltage does not exceed the limit under any condi- tions.
CAUTION:
When the following parts fail, check the High Voltage after replacing.
Location | Name | Name | |
No. | |||
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T461 | Flyback Trans. | TFB3078ZD | |
C447 | Capacitor | 3900pF, ±3% | |
C406 | Capacitor | 1500pF, ±3% | |
C407 | Capacitor | 4700pF, ±3% | |
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ANODE VOLTAGE MEASURING METHOD
CAUTION: Take extra precaution when measuring this high voltage. High voltages are also present in surrounding circuit boards (CRT DRIVE assem- bly, DEFLECTION assembly, and POWER SUPPLY assembly).
1.Disconnect the FBT anode cable as outlined below. Meas- ure high voltage at the point where the cable enters the FBT.
2.Holding the rubber cover firmly, turn it counterclockwise and check that the lock has been disengaged. (See Fig. b on page 8.)
3.Determine the extent of the rubber cover before discon- necting the cable.
4.Pull straight up the anode cable to disconnect.
5.When reconnecting the cable, proceed in the reverse order. After reconnecting, tug on the cable to check that it is secure.
FS CIRCUIT CHECK
The Fail Safe (FS) circuit check is indispensable for the final check in servicing. Checking should be done following the steps below.
1.Turn the receiver on.
2.Temporarily short TP- (R) and TP- (X) on the DEF/POWER Board with a jumper wire.
Raster and sound will disappear.
3.The receiver must remain in this state even after removing the jumper wire. This is the evidence that the FS circuit is functioning properly.
4.To obtain a picture again, temporarily turn the receiver off and allow the FS circuit more than 5 seconds to reset. Then turn the receiver on to produce a normal picture.
Troubleshooting Guide for Fail Safe Circuit
Check that the set returns to normal operation when pin 12 of Z801 is grounded with jumper wire.
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Check the voltage across |
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Capacitor C471 is |
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approximately (C) volts. |
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Refer to table |
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fall safe voltage (C) . |
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YES |
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(See SETTING & ADJUSTING |
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| DATA on page17) |
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NO
Defective Fail Safe Circuit
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