Free Audio Service Manuals - Free download pioneer ct 8 r schematic

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1 . CIRCUIT DESCRIPTIONS 1.1 PLAYBACK FLOW The signal picked up by the playback head is amplified by the equalization amplifiers, Q1701 and Q1703. At the same time, frequency response is corrected. The output from the equalization amplifiers is level-adjusted by variable resistor VR1703 and then applied to Q1705. In addition to being an amplifier, Q1705 also functions to correct fre- quency response. When normal tape is used, Q1707 wiU be ON, and the combination of Q1701, Q1703, and Q1705 will set equalization to 120ps. For metal or CrO2 tape, Q1707 will remain OFF and equaliza- tion will be 70ps. The output from Q1705 is applied to pin 15 of IC601 (HA11226) in the Dolby circuit. Here, it is passed out pin 9. This output is then applied to pin 16 of IC602 and output from pin 9. The out- put signal from IC602 passes via the MONITOR switch to LINE OUTPUT. (A description of the Dolby circuit will be presented later.) 1.2 RECORDING FLOW The signal input to the microphone jack is first amplified by the mic amplifier, IC1501 (NJM- 4558D), then passed via the INPUT selector switch to the INPUT volume. Level is adjusted by the IN- PUT volume and the signal is then applied to the flat amp IC1701 (NJM4558D). The amplifiedsignal is then pa.ssed through the MPX filter and into the Dolby circuit. In the Dolby circuit, it is passed through Q608, IC602 (HA11226), and IC601 (HA11226) before input to the recording ampli- fier. From the recording amp, it is applied to the recording head. 1.3 CONTROL CIRCUIT The control circuitry of this unit is contained in CPU PD6006, expansion IC PM3001, and IC PA3010 used in the MS function. The key signals applied to PD6006 are transmitted to PM3001 as 16-bit serial data, and PM3001 then uses this data to control the various circuits. When a mode key is activated, the 16-bit serial data transmission is output from pin 5 of PD6006. This is shown in Fig. 1-1. Also a clock pulse is output from pin 7. (Data and clock pulse trans- mission occurs once each time the key isactivated.) The 16-bit serial data is applied to pin 3 of the expansion IC, PM3001, and the leading edge of the clock pulse is read into the shift register of PM 3001 through pin 2. After both read events are completed, a STB (strobe) pulse is applied to pin 1, and PM3001 then starts transmitting control signals from its various output pins in accordance with which key was activated. (Refer to Fig. 1-3.) The following sections will describe the various circuit operations occurring when a mode key is activated. Operations will be described for the FWD direction of travel. (Except where other- wise specified, the pin nos. will be for PM3001.) The DOLBY MUTE circuit shown in the signal path diagram (Fig. 1-1) tums Q313 ON to mute all circuik only when the position of the Dolby switch is changed. 1. STOP Mode Key ON -Power switch ON Mechanism The 16-bit serial data transmission from PD6006 will cause pin 7 and 8 of PM3001 to go high, tuming SOL L and R OFF. The mechanism will thus be placed in a STOP status. Motor Pin 4 and 5 will be low. and the reel motor will be in a STOP status. Signal Path and other circuits When pin 9 is high, Q621, Q311, and Q1603 are all ON. This causes LINE OUTPUT and the head- phone amp to be muted. If pin 11 also goes high, Q309 is tumed ON, placing the REC AMP input at a ground potential. When pins 12 and 13 go low, Q302 tums OFF, stopping the bias oscillator circuit, and extinguishing the REC IND. Muting is applied to all circuits in a STOP status. 2. PLAY Mode Key ON Mechanism Pin 7 and 8 of PM3001 go low, activating SOL L and R. (Refer to the timing chart in Fig. 1-5.) This places the mechanism in the PLAY mode. Motor Pin 4 goes to a low level, while pin 5 is held at a middle (M) level, causing RM R (reel-motor R) to start turning. P06006 t--"= Fig. 1-1 PD6006 Data output 3 35)S

Pioneer ct 8 r schematic

Extracted text from pioneer ct 8 r schematic (Ocr-read)

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