User manual NAKAMICHI DRAGON

[. . . ] Erase Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Double Capstan Tape Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mechanism Control Cam Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] signal is kept L for a short period of time because the delay circuit (C605 and R608) connected in parallel to FF Button acts to prolong the NOT k. f. f = L signal. In this period, the voltage at the point A becomes approx. +22 V from +23 V pulse-likely as R486 and R488 are grounded by the NOT Kf. f = L and NOT Kplay = L signals respectively. Consequently, Q424 and Q426 are turned ON, and C411 is charged up to +24 V, but C411 will be discharged after this period is over. The base current to Q430 is supplied from C411 through D424 and R475, as a result, Q430 and 0429 are turned ON, Q428 is turned OFF, and +24 VS is shut off resulting in STOP mode. On the other hand, since the base current to Q427 is supplied from C411 through R469, R427 is turned ON until the discharge of C411 is completed. When the voltage of C411 is lower than the emitter voltage (approx. 4. 2 V) of Q430, Q430 and Q429 are cut off, Q428 is turned ON, and +24 VS is supplied, as a result, the PLAY signal becomes H (+24 VS) and PLAY mode is set. 2) From RECORD mode to FF or REW mode When mode is changed from RECORD to FF or REW mode, momentary STOP mode is automatically taken in view of the tape deck mechanism, and after this is over, a new mode is set. When Record Button is released by pressing either FF or REW Button, Q419 is turned from ON to OFF, therefore, a negative differentiated pulse is applied to the point A via C421 (22 uF). This negative pulse acts to turn ON Q424 and Q426, as a result, C411 is charged up to +24 V. The motor is driven by the differential amplifier IC402 (1/2) and drivers Q405 and Q406. In the control motor stop condition, both voltages at pins No. 5 (non-inverting input) and No. 6 (inverting input) of lC402 (1/2) are equal and the difference of both inputs is zero. When a new mode is demanded, the balance of both inputs is broken, as a result, the control motor is driven until both inputs are balanced. The cam control variable resistor VR601 moves synchronously with the motor so that the voltage at the sliding contact of VR601 is changed. When the voltage at the sliding contact of VR601 is changed and the input difference of the differential Mode Record Stop FF/REW Play/Pause Play ON Q403, Q410 pulse Q404, Q410 D417 ON amplifier IC402 (1/2) becomes zero, the control motor stops. The following table shows the relationship between cam position and the voltage at the sliding contact of the cam control variable resistor VR601, and the state of transistors in each mode. Position on Cam Record Stop FF/REWPause Play Typical Voltage at Sliding Contact of Corn Control Volume 16V 15V 13. 5V I0V 7. 5V Q412 Q412 Q412 Q411, Q412 Q411 OFF Q404 Q403, Q404, Q410 Q403 Q403, Q404, Q410 Q403, Q404, Q410 Q411 Q411 Q411 Q412 15 2. 3. 8. One end of the reel motor is connected with +12 V and the other end is a terminal for controlling. During FF mode, Q413 is turned ON and the reel motor is grounded. Accordingly, the reel motor turns in the direction of fast-forwarding. On the other hand, during REW mode, +24 V (REW H) is applied to the reel motor and the reel motor turns in the direction of rewinding. [. . . ] Playback Head and Record Head Height Adjustment and Azimuth Alignment", "5. 8. Record Head Stroke Adjustment", etc. As a case may be, the said waving or slippage may have been caused from defective supply Pressure Roller Ass'y or Take-up Pressure Roller Ass'y without parallel contact with capstans. If such are noted, the Pressure Roller Assemblies will have to be replaced. [. . . ]