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A/V INPUT AND OUTPUT CHECK TROUBLESHOOTING
Circuits to be checked: 100% mod.). � IC501, 502 and its
1. AUDIO/VIDEO OUTPUT CHECK
1. Receive the E-12CH "PAL COLOUR BAR" signal (100% white colour bar, sound 400Hz,
adjacent circuit
SCANVERTICALNO
2. Terminate video with a 75-ohm impedance. Make sure the output is as specified
(1.0Vp-p ± 3dB).
Normal Abnormal
Check the voltage at pin (6) of IC501 and pin (3) of IC502.
3. Terminate audio with a 10k-ohm impedance. Make sure the output is as specified
(1.76Vp-p ± 3dB).
2. AUDIO/VIDEO CHECK, S-TERMINAL INPUT CHECK
Check L1501, D1605, D1506 AV1, AV2, AV3 TV again that video and audio outputs are according to the input and R1650. and output terminals for each mode.
1. Using TV/AV key on remote controller, make sure that the modes change in order of TV,
Check vertical trigger purse at pin (64) of IC801.
2. In AV1 mode, connect connector to S-VIDEO input terminal. Make sure the AV
Normal Abnormal
mode changes to S-VIDEO mode, the unit functions well, and that "AV1-S" appears on the screen.
3. AV3 AUTOMATIC ID CHECKING
IC501, IC502 Check IC801 and its 1. Using the remote controller, receive a TV broadcast signal. and related circuits peripheral parts. 2. Feed signal to VIDEO input terminal. Make sure the AV3 mode shows up auto-
matically. *Setting:AUTO SELECT to be turn on.
Note1: Make sure that switch S1006 is at the position for service mode, not for the horizontal centering mode. (At center or farthest position, the switch is for normal mode.) The "9" key on the remote controller is used to turn on and off these modes. IC1001 in oder not to activate the vertical no-scan protector. troubleshooting on the following pages.
9
PROTECTOR PERFORMANCE CHECK Note2: The vertical sync signal must be fed to pin (62) of
1. BEAM PROTECTOR Take this measure with protector circuit for the
1. Receive the E-5CH "MONOSCOPE PATTERN" signal. 2. Set the contrast control to maximmum. 3. Set the brightness control to maximum. 4. Make a short-circuit between collector emitter of Q853 and make sure that the protec-
tor activated and the stand-by mode is called.
2. HIGH-VOLTAGE PROTECTOR
1. Receive the E-5CH "MONOSCOPE PATTERN" signal. 2. Connect bias box to the cathode (R1625 side) of D1607. 3. Adjust bias box voltage to 16V and make sure that the protector is not activated.
�Reference: usually about 19V
4. Boost bias box voltage to 24V and make sure that the protector is activated.
3. OTHER PROTECTORS
1. In checking performance other protectors � for example, the one against shorting of
smoothing electolytic capacitor of + B line �, pay attention not to damage or deteriorate element.
SX-68JS7 SX-68JS9
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