Scully 280 Series - Page 15

SI:;CTION i
TA P E TRANSPO RT
4. 1. OESC PJP TION
4. I. I. Tape Drive
The l.:odel 280 Recorder !Rep r odutflr
employs a I hrtf!-motor drh'e ay.lcm _ a t.....,-
apeed hysterUIS synchronous tap8tan drl\'C
motor and two in!lJcUon-lype torque motors.
The (:ipSlan ",olor and Ihe aoleno ld attuated
prusUNl rolln dri, ... the lape at a lUlifor m
apeed in t he reprodute , r ecord , and edit modes.
The tapetan r:>Oio r has I....., &etl of windln($ to
provide a and a low t ape lpeed, eUher of
which may he selected by the tajlliU.n Soeed
Switch, loca t ed on the control panel of l he lape
Iranlporl. !'"orthe Model 280 with M oUon sens-
Ing. Or the Mo:tel 280jSP -14 , allo N!ler to sec -
tion 6A Or 6B respectively .
When the Start button Is prnnd , the
capslan soleno id and brake loleoolds are entlr -
,bed. The capstan solenoid e"iatl:U thtl nlbber
pressuN' rollu to the capstan by means of a
mechanLc:lI IIr.kage , pN'8Bing tile tape between
the r oller and capstan firmly. T hecapetan mo -
t or provides the COMtant t ape.peed; c_bo t
lape motion Is assured by the clampln&: action
0( t he preuure roller.
In tile rut modes (forwa rd and rtlwind),
the torque motors drh ... the tape and the cap-
atan motor an d pressure rollers artl inactl"e,
The motor acting as t akeup ",1\5 ",lIh full voll-
atI:\!; IIIe one on the supply "(Ie Operatea wllh
low vollage 50 as to provide proper tape l en-
lion and pr\!Ve.1t a loose wind..
,.
f
4. l. 2. Brak\! $x.lem (see figs. 4_1 and 8-1.)
The Scully brake .ystem Is a disc type
employIng an electrically control1\!d dlfferen-
lIaL Ther\! II AC in the lorque motors . t all
t imes, Includlng t he STOP position, as long as
t t.ere Is lape correctly thN!aded In the madllne,
8r:01r.In&: force Is a IlUlclion of the
sprIngs (3, 4 ). It may be at\jLlliited by the
adjusting sere .... (I, 2). The sprJ.ngs are nor-
mally Se! 110 that they will Jw;t OVerCOme the
low AC vo lt age on the torqUtl motora. '0 the
"wy " ,,,,I f_1 til """rallon, tJ>e trake
solenoids aN! fully enel"lLud, permitting free
rotation of the rettl table.. The brake shoe (6)
Is fastened to the 10ieDOId plunger , but Is free
10 align itseU squarely aa:alnst th e rotating disc
(5) which 18 Integ r al with the Iorque molor.
M echanically, the takeup and supply .... -
s. mblles are Identical. There Is no prov\Slon
for mechanlcal bruin&: differential as a func-
tion of rotational senae. The dlfferentbll. ob-
tained electrla.lly by feeding N!"'ced torque
,""Cltage to t he reel motors .. -heo brakes are
e[erglzed {braktl IOlenoldli de-enel"llz.edj.
With the brakes on In the F ast r .. ·d..
mJde, the takeup r eel motor OVtlrCOmeS .ome
oflhe bruin&: force while the supply reel motor
aCds 10 the braking force, Ihe dlfferenlbl tel""
oI:tained from the rotation of the moton. The
Is true In the RewInd mode.
!'"Igure 4-1. Disc D,ak e Outline