Fostex B-16 - Page 12

4. THEORY OF OPERATION
4.1 LSI peripheral control circuits
Control signals which are basic fundamentals in tape transport operation
are generated by a TTL type LSI, 014.
1) CR 1 (014-5)
' This is the reset signal input pin of 014. During the short period after
switch ON of power until Q3 switches on, U14-5 is kept at "L" level and
thus U14 is reset.
During the period when C12 is being charged, Ull-10 and U6-4 go to
"H" level via D13 and D14, to reset each D flip-flop. At the same time,
the CR-1 input signal puts 06-10 to "II" level which resets this flip-flop.
2) EBR IN (U14-4)
When the STOP button is depressed during the F.FWD or RWD mode, the trans 
port temporarily goes into the reverse tape travel mode. Then, “ L" level
is input to EBR IN and then into STOP mode to apply the mechanical brakes.
When tape speed decelerates to about 38 ips, an "L" level is applied to
EBR IN from 07-6. This is due to the nature of the circuit such that the
height of the saw tooth wave at the collector of Q4 generated by the
motion pulse becomes higher with progressively slower tape speeds. The
timing chart is shown in Fig. 4.1.
Fig. 4.1
3) ZERO RTN
When the ZERO RTN button is depressed, the transport goes into RWD or F.FWD
and when the counter reaches "0", it will go into the PLAY or STOP mode.
When the ZERO RTN button is depressed, 06-8 goes to "n" level by 03-11
flip-flop U6 is set, 06-13 goes to "H" and 06-12 goes to "L". At the same
time, 03 — 5 and 03-2 goes to "11 “ level and if the. counter display is
then 03-1 will be “ H" level, an “ L" level will be input at 014-2 and the
transport will go into REWIND. If the display is 03-6 will be “ ll",
an L level will be input at 014-3 and the transport will go into F.FWD.
After going into the REWIND or F.FWD mode, tape will go to mid-speed when
the counter reaches ±1 minute, low speed at ±10 seconds, and when it