devices are produced on reels of 16
mm film tape . Watching parts being
assembled using the TAB format is
like watching a newspaper being
printed .
Because of the myriad of devices
which have been fabricated and are
in use daily , the packaging becomes
an important part of the integrated
circuit. There are plastic , ceramic ,
hybrid , and metal containers used as
packages for all kinds of applications .
You will find flat packs , W-packs ,
DIP ( dual in -line package) , SIP
( single in -line package) , plastic
packs , ceramic packs , lead torms on
substrates , metal headers , hybrid
packages, and specially tooled
configurations which employ more
than one material.
Therefore, and depending on
what the device was designed to do ,
the assembly which is known as an
integrated circuit is capable of
component failure as is the chip die
capable of device failure . Now the
component part - integrated circuit
( regardless of its integration size
LSI -MSI -SSI) is ready to be inserted
into someone's circuit board .
Just when I was beginning to
understand the part itself, I'm now
faced with a larger and more
complex problem where one small
chip is insignificant to the more
complex array of the circuit board .
This means that a circuit board of
100 ICs all being sixteen -pin devices
would have 3200 wire bonds to
possibly fail ( 16 pins X 2 bonds) X
( 100 ICs) = 3200 . It would have
100 die attaches which could go bad .
Th ere co uld be 1600 solder joints
which could go bad . There could be
100 circuit chips which co uld go bad .
And to top it all off . any one of these
problems might not e ve n show up
until after it heated up and became
unstable .
Th e job of the technician is
thankless but so in credibly important .
Anal yzing circuit s is a chore because
of th e possibilities that any one of
5000 th ings could go wrong on a
simple board of 100 ICs like the one
pre vio usly discussed . This article is
my way of saluting all the bench
techs of th e world'
Next in this three-part series on
"Semiconductor Device Techno-
logy " in UPDATE : Chip functions .
Acceptor hang-ups' cure
By Zac 0 live r
Recently , Midway Manufacturing
Co . issued a service bulletin referring
to free games obtained by flipping
pennies up , through the coin return
cups , and activating the coin switch .
So , if one of your Midway games
has been fed with pennies , you can
prevent that by ordering the Anti -
Penny Field Kit from Midway's Parts
Department. The kit part number is
Ao90-00064 -0000 and instructions
for installation are included .
However , there are other methods
to insert pennies and / or obtain free
games . All that is required is a nickel
coin that will hang in the acceptor .
Usually , metal acceptors will reject
nickel coins , as the coin will slide
through the swivel gate , straight
down to the return chutes . A
damaged nickel coin, however,
might hang right after the gate . A
penny then dropped will bounce
over the nickel and will be directed to
the acceptance chutes , activating the
coin switch and , what is worse ,
returning the damaged nickel to the
customer. A few adjustments will
prevent most nickels from hanging in
the acceptor .
Nevertheless , field tests showed us
that the most economical solution , in
the worst cases , was to replace the
acceptor for a plastic one. These new
coin acceptors by Coinco , already in
use by some manufacturers , are
virtually trouble -free . The cost per
unit is approximately $12 , but
sometimes it's well worth it!
Unfortunately , it will not fit in all
games . Atari's coin door , left side,
due to the coin lockout wire bracket,
will not allow the insertion of the
acceptor .
Also , the adjustment of the coin
switch wire , in Midway's coin door , is
important to prevent coins from
getting jammed in the last coin chute ,
just before the cash box . Adjust the
wire with a long -nose pliars, so that
the short arm of the wireform will
move the closest to its slot walls .
(See Figure .)
COII"' SWITCH ACTIVATOR ARI'I
If the cash box cover is not
properly positioned it will also cause
the coins to hang . Light blows on the
door will vibrate the micro switch
contacts , now closed , stepping up
the credits . Since the coin meter coil
is activated during the closure of the
switch , overheating of the driver
transistor will occur . The cash box
cover guides ( metal brackets on
each side of the cash box pit) might
be tightened to prevent the lid from
sliding .
Still on Space Invaders, when
garbage lines appear on screen or
extra credits are given , Andy Ducay ,
service manager , advises :
1. - Check game board for
proper RRC capacitor grounding .
This refers to earlier boards where
some of the capacitors in the network
not
properly
grounded.
were
( P . C . Ao84-90700-D739) [ See
PLAY METER, March 15 , 1980,
page 68. - Editor]
2. - Clean game board edge
connector and inspect Mother Board
72 Pin connector. You know - the
old story retold : Watch for that
interface!
3. -
When installing or re-
installing the game , measure + 5,
+ 12 and -5 V . D. C . at edge
connector of Mother Board . Use
ground reference also from the board
and not from the supply. Adjust
voltages using pots on Power
Supply .
4.
Replace possible heat
sensitive 8080 CPU, manufactured
by Texas Instruments ( Tl) with 7919
date code .
5 . - Add a Cor-Com line filter
( Midway's part number 0017-00003
-0114) to the AC input line and if
you want to go strong , add a varistor
(typically a Vl30 LA lOA made by
G. E. ) across the output line of the
line filter .
6 . - Inspect soldering of bit
shifters on game board ( ICs 25S 10
or 74151) .
t
In all , let's keep those silvery discs
rolling in, and as Roger Sharpe a l-
ways says , be well and prosper.