S*TJ DECEMBER 1981 10
TWO COIN/ONE PLAY CIRCUIT REDESIGN
BY PAUL CHAMBERLAIN, P&P AMUSEMENT, BRANTFORD, ONT ARIO
Regarding the schematic on page six of the Sept. '81 Star*Tech
Journal for a 2 coin/1 play modification. It's a great idea but it doesn't work for the
following reasons:
(1) The diagram shown is not correct.
(2) Even with the correction it still did not work properly without
further modifications.
(3) The design is not compatible with many of todays' games.
After many frustrating hours and several phone calls to Star* Tech
Journal for consultation, I have developed a design that works well with any game.
The solutions are as follows:
(1) On the original drawing for IC. 7473 the symbols for Q and Q
were transposed. Q should read Q and vice-versa.
(2) a, After correcting fault no. 1, I found that the pulse from 7473
was of too short a duration to fully engage the armature of the relay. This was
corrected by adding a 100 Mf d 16 v. capacitor across the coil of the relay.
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(2) b, This worked OK when the coin switch was activated l ·y
hand slowly, but when used on an actual rejector is proved to be erratic giving
credit for 1 coin or sometimes requiring 3 or more. This problem was cured by
changing the .1 cap across gate no. 1 on 7400 to a 1.0 cap.
(3) Since many games today use S.P.D.T. micro switches (all three
connections used for a make & break circuit) the original relay with S.P .D. T. contacts
was not compatible with this type. To correct this I replaced it with a D.P.D.T. type
wired as shown in our schematic.
We are currently operating an assortment of 150 games, music and
pool tables on our route and due to higher prices here (50% more than U.S.)
caused by our Canadian taxes, Customs duty, and a devalued Dollar we have
operated all pool tables and videos from "Space Invaders" up on 50¢ play, with
music on 1 play for 25¢/Three plays for 50¢.
We recommend anyone going to 50¢ play to post a sign clearly on
each game to prevent customers from trying to force two coins side by side into 1 slot
and jamming them or on dual chute games from putting one coin in each slot at the
same time and getting credit for only one coin. Some will still try but we assume they
can't read.
We will be getting a printed circuit board made of our unit for use
on our own route and if any one is interested they can contact us and we will be happy
to supply them for a moderate price.
We find S*TJ very useful and informative. No serviceman should
be without it. Keep up the good work!