MITS altair 680b User manual

altair 68Ob
II.
MAIN PC
BOARD
ASSEMBLY
ICSocketandIC Installation
Capac'i
tor Instal
Iation
ResistorInstallation
Transi
stor Instal
Iation
Diode
andCrystal
Installation
Voltage
Regulator
Installation
BridgeRect
j
fier Instal
I
at'ion
ConnectorInstal
I
ation
Input/0utput
Confi
gurations
Jumper
Wire
Connections
Paper
TapeReader
Control
M0S
IC Installation

IC SocketInstal
I
ation
Thereare 15
onthe 6B0b
Instal
I the
instructi
ons
The
s'ize
for
IC
sockets
to beinstalled
t,lai
n PC
Board.
ICsockets
according
to the
qjven
on
page
7, sectionB.
each
socketis listed below.
The
ICs
that areto be'installed'into
these
sockets
arealI stati
c-sens'it'ive
I40S
ICs. (see
page
6
)
Install onl.v
thesockets
at this t'ime.
D0NOTinstall the ICsin the
sockets
unt'il theMain PC
Board
hasbeen
com-
pletely
assembled.
15
IC Desi
qnat'ion
( ) c,
D,
Eo
F,
G,
H,
J, K,
and
Z
O T, U,
V, l^J,
and
JJ
( ) ilN
16
pin
24 pin
40
pin

iC Installation
There
are3l ICs
to be
jnstalled
(with-
out sockets)
ontotire
6B0b
Majn
PC
Board.
Instal
I these
ICs
accordi
ng
to the 'in-
structionson
page
7, section
A. The
correct part numbersfor the ICs are
listedbelow.
Part I'lumber
il A, B,
X,HH,MM,VV,
()
()
()
()
()
()
()
()
()
()
()
and 7Z
L (Baudot only)*
M
ll and P
R,S, CC,
and
PP
Y
AA,KK,LL,andUU
BB
DD,
EE,and
FF
GGandSS
TT
RR,I,l'',l,
XX,
and
YY
741S04
74L574
74LSl
0
74LS0l
4050**
741S00
741S30
4449**
74L520
74L502
741S73
74367
(or BT97)
*i'l0TE:Install ICL 0iiLYif a
Baudottermi
naFs to be
i
nterfaced
to the 680b.
**Stat'i
c-Sensi
ti ve MOSICs.
See
page
6 beforeinstalling.
l6

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11

Capaci
tor Instal Iation
There
are 6 electrolvtic capacitors
(cl,
c2,
c3,c4,
c5,andclb),I
tantalum
capacitor
(C6),
and43cer-
amic
disk
capacitors
(C7
through
C14
and
C50
throuqhCB4)
to beinstalled
onthe MainPC
Board. Install the
electrolytic capacitorsand
the tan-
talum
capacitoraccording
to the
instructions
given
on
page
9, Sec-
tion A. Install theceramicdisk
capacitors
accordinq
to the instruc-
tions
on
page
9, Section
B.
The
valuesfor all 50capacitorsare
Iisted
below.
i
tor Val ues
()ct,c2,
()c4,c5
( ) co
()c7,cB
( ) cg,cto
()cil
LJ 35uf
.l00
uf
luf
56
pf
430
.001
50
pf
.0.|
uf
.l uf
3300
uf
pf
uf
( ) ct2
( ) cr3
*( ) Cl4,C50
throuqh
CB4
( )
crs
*NOTE:Save
the
Ieads
cl
through
extra capaci
tor
ippedfrom
C50
CB4for later use.
t8

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r9

Res
is
tor Ins ta
IIation
Instal
I the fol I
owinq
on the l'lainPCBoard.
structions listed on
37
resistors
Use
thein-
N0TE:
Al'l of the resistors
onthe
Main
PC
Board
are either 1/4
watt or 1/2watt, except
R21,
which
is a 2-watt
res.istor.
page
B.
Resistor
Values
and
Color
Codes
I
) Rl throughR9,Rl5,R30
) Rl0,
Rll, Rl3,Rl7,
RIB
) Rr2
) Rt4
) Rt6
) Rl9,R20
) R2r
) R22
) R23,
R2B
) R24,
R25,R26,R27,
R3l,R32
) Rze
yel
Iow,
violet
, red
brown,
black,
orange
orange,
orange,orange
orange,
oranqe,brown
brown,black,
blue
orange,
orange,
red
(2
watt), brown,
gFeer,
black
brown,
b1ack,
red
ye'l
1ow,
violet, b1 ack
yel
Iow,
v'io1et,
brown
brown,b1
ack, brown
4.7K
ohm,
l0K
ohm,
33Kohm,
330
ohm,
10M
ohm,
3.3K
ohm,
15ohm
1K
ohm,
47
ohm,
470ohm,
100
ohm,
Res'istorPack
Instal
I
ation
After
installing
a1l
37resistors,
the 4 resistor packs
(RPl
through
RP4)
mustbe
installed. There-
sistors within these
packs
eachhave
a value
of 4.7Kohms.Each
pack
has
a smalldot printed
at one
end.
Thisdot must
correspondwith the
dot printeE-on
the PCBoard. Use
thefollowing
instructions
to in-
stall each
resistor
pack.
l. Install theresistor
pack
at
a perpendicular
angle
to the
silk-screened
side
of the
board. Make
surethe dot on
the resi stor pack i
s a1i
gned
with the dot printed
onthe
PC
Board.
Tape
the resistor pack
in place
andturn the boardover. Be-
fore solderinq,
check
that the
resistor
pack
is still perpen-
dicular to the board. Carefully
solder
each
pin of theresistor
pack
to the foil patternon the
backof the board.+
Turn
the boardoveraqainand
remove
the tape.
( ) RPI
through
RP4are 4.7Kohm
resistor packs
2.
?
*N0TE:
The
foil pattern
onthe
solder
mask.
Thesoldermasks
back
of the boardis
helps
prevent
solderpartially covered
by a
bri
dgesacross
I
ands.

Special lnsert Page
RESISTOR
PACK
SUBSTITUTIOi'IS
ALTAIR
6BObI'IAIN
PCBOARD
Due
to supplyshortages,
your
6B0b
kit hasbeen
shipped
to you
wjthout
thefour4.7K
ohm
Resistor
Packs
(npt-np+)
calledfor on page
20
of theAssemblyManual.
Nine
4.7K
ohm,
1/4
wattres'istors
have
been
substituted
for each
pack. These
substitute
resistors
mustbe
installed
according
to thedjrections
outljned
below.
Substi
tute Resi stors
, RPI
-RP4
Instal
IationProcedure
i"lote
that each res'istor
pack
designation
on
the
silk screenhas
l0 holes. The
left-mostholeis marked
on
thesilk
screenwith a dot.
Beginning
with
the
box
labeled
RP1,
in-
sert one4.7K
ohm,1/4watt (ye1'low-
violet-red
) resi
stor vertica1
'ly into the
right-most
hole
in the box. Bend
the
top lead at two
rjght angles,asshown
jn the diagram,
sothat the endof the
free lead
maybe
insertedinto the hole
markedwith a dot. Solder
the two
in-
sertedleads to the foil patternonthe
back
of the board.
Insert the remai
n'ingei
ght 4.7Kohm,
l/4 watt resistors
vertically into the
remainingeight
ho1es.Soldereach
of
the top'leads
to the common horizontal
leadof the fjrst resistor. It may be
helpful to bend
the top leads
against
the horizontal
leadfor better contact
beforeso1dering.
Solderthe inserted leads
of the
eight
resistors
to the foil pattern on
the
back
of the board. Clin all excess
leadsfromthe torr
and
bottomof the
res'istors.
Repeatthis procedure
for RPZ,RP3 and
RP4.
J.
t.
2
A
q
Resistor Instal
I
ati
on Completed
Resistor
Assembly

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