Apple Macintosh - Page 293

Troubleshooting and Operation Hints 297
The Mac Display
By far th e l argest sing le co mp one nt in t he Maci nt os h is the
disp l ay. T he recta ngular displ ay on the fro nt of th e M ac mai n
system
uni t is in reality th e face of a l arge vac uum tub e. In th is
age of high tec hn ol ogy where mo st vac uum t ub es are ob so lete,
we h
ave yet to fi nd an ade qu a te re placeme nt for th e sta n da rd
pic tur e tu be.
In o rd er to cr ea te a display, th e t ub e sh oo ts a b ea m of
el
ec t ro ns at the d ispl ay scr ee n whi ch is cove red with a ph os-
ph oro us ma t eria l. To ai m thi s beam , the tu be uses a c lu st er of
m
ag n ets which steer th e el ec t ro ns as th ey p ass t hr ough their
m
ag netic fields. A ll thi s ha rd wa re re quir es a varie ty of high
vo lt ages which th e Mac ge nerates fro m th e electricity it
receives. The
circu it ry for th ese vo lt ages resides a long the l ef t
side
of th e M ac system un it. We r eco mm e nd th at yo u r efrai n
from pl
ac in g any th ing co nt a inin g li quid upon th e ma in unit.
Any l eakage th roug h th e vents in th e t op co uld cause extens ive
dam
age to th e Mac.
On ce th e M ac h as b ee n prop erly in stalled, turn on th e
m
ai n unit. T he p owe r sw itch is l oca ted on th e rig ht side of th e
b
ack of th e main co n so le. Th e sw itch is la beled wi th a" I "a nd a
"0 " th a t re pr ese nt s th e co ndition s of "o n" a nd "off ," resp ec -
tively.
Wh en the Mac is f ir st p ow er ed on, it should e mit a sho rt
tone. T he sc r ee n will rema in blan k while th e pic tur e tube
wa rm s up . After a few seco nd s, a displ ay wi ll a pp ear. If not,
ch
ec k to see th at t he unit is properly pl ugge d into a wa ll socke t.
T he in
tensi ty co ntrol may be se t t oo l ow for a di sp l ay. The
co n tro l is l oca t ed on th e l ef t side of th e M ac's face im me di ate ly
below
th e A ppl e l ogo. To turn up th e intensity, turn th e di al
cl
ockw ise. If there is still no dis pl ay, the ow n er should co nt ac t
an
au th or ized r epa ir serv ice.