IBM 727, Manual Of Instruction, Page: 125 / 163

16-3 (76.09.09) Opens the circuit around the load-point and tape-indicator
photo-cell lamps when drive is unloaded.
16-4 ( 76.09.06)
Drops the circuit to the head lock solenoid when the drive is
unloaded.
R17, Power on reset
17-1 (76.09.01)
17-3 (76.09.04)
Picks when +48 volts is up and holds until 48 volts drops.
Drops R l, HD1, HD2, and HD3 if +48 volts drops.
Prevents picking of the R3 relay when the power is coming
up.
17-4 (76.09.08)
Prevents picking R12 when power is coming up.
R21, Rewind PU
(76.09.05)
Picks up from relay driver T03J4B (76. 08). T03J4B is
conditioned either from a call from CPU or manual load r e ­
wind operation.
21-1 (76.09.04) Completes the circuit to pick R3 at start of any rewind opera­
tion.
21-2 (76.09.09)
21-3 (76.09.09) Latch trips R16 to take the drive out of unload status.
Latch trips R16 to take drive out of unload status.
R23, High-speed r e ­
wind status (76.09.05)
23-1 (76.10.01)
Picks when the tape is out of both columns and the head is
up at the start of a load-rewind operation.
Opens the circuit for 1/2 brake on the right reel during
high-speed rewind.
23-2 (76.09.02) Makes a circuit to pick R24 and R27 during high-speed r e ­
wind.
R24, High-speed r e - Picks at any time that R23 picks,
wind interlock (76. 09.02)
24-1 (76. 09. 09) Opens and allows the tape break light to operate during a
24-2 (76.10.01)
high-speed rewind operation.
Opens the circu it for half brake on the left reel during high­
speed rewind.
24-3 (76.09.02) Keeps GO status relay (R27) up during high-speed rewind.
This holds the idlers out of the tape path.
24-5 (76.09.02)
Opens the circuit to pick DP4 during high-speed rewind.
R25, Load point relay
(76.09.05) Latch pick
(76. 09. 03) Latch trip
25-1 (76.09.02)
Latch picks when the tape has reached load point during load
rewind.
Latch trips when tape moves off load point.
Disables manual backward control if the tape is setting at
load point.
25-2 (76.09.04)
25-3 (76.09.08)
25-4 (76.09.03) Opens the circuit to pick R3 if tape is setting at load point.
Drops R12 (rewind status) when load point is reached.
Brings " At load point" up to (76. 04). "At load point" ANDfs
with "start" to pick R26 and goes through OR circuit C12F
to AND with "se le ct" to bring up "s e l & at load poin t."
R26, Load point trip
(76.09.05)
26-1 (76.09.03)
t
Picks when "start" com es up if the tape is setting at load
point.
Completes a circuit to latch trip R25 when tape moves off
load point.
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