User manual NAKAMICHI DRAGON

[. . . ] Erase Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mechanism Control Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Power-mute = L signal is produced pulse-likely when Power Switch is turned ON or OFF. This L pulse mutes the amp, circuit and also acts to shut off the shut off circuit initially. (1) Power Switch ON Q433 is turned ON at every positive half cycle of the out put from the secondary winding of the power transformer. When Q433 is turned ON, C416 is discharged, as a result, the voltage of C416 can not exceed the VBE of Q432, and Q432 is in the cutoff state. Therefore, the Power-mute =L pulse is produced for a certain period of time when +24 V is built up after Power Switch is turned ON. The Power-mute= Lsignal makes Q4l6 to turn ON, as a re -sult, Mute signal becomes H and the amp. circuit is muted. Meanwhile, the Power-mute = L pulse is applied to the shut-off circuit and shut-off is activated. (2) Power Switch OFF The output from the secondary winding of the power transformer ceases quickly, and Q433 is turned OFF. Consequently, the base current flows to Q432 through RDRAGON, Q432 is turned ON, and the Power-mute signal becomes L. The Power-mute = L signal makes Q416 to turn ON, as a result, Mute signal becomes H and the amp. At the same time, shut-off circuit is shut off by the Power-mute = L signal. 2. 3. 4, Auto Shut-off Circuit Refer to Fig. When Play Button is pressed, it is locked ON and FF Button is released. 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. +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. 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. FF or REW mode is set after passing through a certain period of STOP mode in the same manner as above (1). [. . . ] Check to insure freedom from gap between the Block C and record head surface, then tighten the 2 pcs. If the above are inaccurate, items (1) through (15) will have to be repeated till satisfactory results are obtained. 5. 9. Tape Travelling Adjustment The adjustment shall be made with a modified version of the current type EXII C-90 as shown in Fig. 5. 16 (error will be made if a current type Tape Travelling Cassette (DAO9011A) should be used for this purpose). [. . . ]