Re: Sharp TRP801
The +12volt supply for the IF amplifiers and tuner is derived from the line output transformer. Because the line output stage doesn't work the power supplier has been connected direct to the IF board. All the transistors are PNP types and the circuits are of the "upside down" type, that is, the supply rail is positive and the transistor collectors are connected to near ground potential.
The vision IF amplifier doesn't work but at least the sound IF amplifier does and is delivering almost 4 volts P - P of audio across the detector load resistor.
The sound intermediate frequency has been determined to be 14Mhz and this will be the frequency for both TV standards. The AVC is efficient, maintaining a constant voltage across the load resistor irrespective of signal levels.
DFWB.
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