Sharp 21N52-E1 - TROUBLESHOOTING: NO PICTURE, NO SOUND; NO PICTURE, NO SOUND DIAGNOSIS

CIRCUITS TO BE CHECKED:
l Tuner.
NO PICTURE, NO SOUND
. PIF.
l Automatic Gain Control.
0 12V + B2 Power Source.
Does the noise level increqse at max.
Contrast, Brightness and Sound controls?
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Noise increases but no signal is
received.
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Check the tuner BL, BH, Bu and
+ B2 biases.
+ 62 must be approx. IZV.
BL must be approx. l2Vand
BH must be approx. 12V with the
preset switch at VHF position.
Bu must be approx. 12V with the
band switch at UHF position.
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Picture noise decreases but sound
level varies greatly.
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Does the I2V +B appear at pin
(11) of connector- ?
Check the tuner AGC.
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Normal Abnormal
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