IBM 727 Manual Of Instruction page 24

The following relays can pick with the 48v DC supply, because the tape unit is
assumed to be unloaded.
Systems Sequence of
Operation
R21, R26, unload,
are latched.
Pick R i l , R22,
05D
unload.
01H Pick R14, photo
light.
05F Pick R8, head
cover not down.
06H Pick R13, clutch
transfer.
05G Pick R7, cap­
stans in.
10.01 Full power to both
stop clutches.
After a five-minute w arm -
unit.
01C Pick R17, power
on.
06H Pick HD3, phase
3.
02J Reset R/W status
tgr. to read status.
02J Reset tape indi­
cator tgr.
02E Manual start line
up
Conditions
R21-4n/o
Head cover down m icro­
switch
R11BU
Capstans in microswitch
RIAU n/c, R4ALn/c
RIBU n/c, R4BLn/c
up period, DC supplies are available from the control
When all DC supplies are
available from control
unit
R17-4n/o
R 20-3n/c
R 22-4n/o
R 22-3n /o, R7AUn/o
R6BUn/c
24
Remarks
These relays were latched
the last time the machine
was unloaded.
Circuit through the load
point, tape end, and tape
break light.
Vacuum column switches
have no control over reel
clutches.
Power to stop clutches
can be interrupted by
pressing reel release
button.
Keep the moving pulleys
away from stop capstans