Star Tech Journal

August 1992
STAR*TECH Journal
Data East
Pinball
No Display
+5 VOLT ADJUSTMENT
MODIFICATION FOR
COMPUTER-TYPE SUPPLIES
Sam Cross
Godwin Distributing
North Little Rock, Arkansas
James Beck
Greater Southern Distributing
Atlanta, Georgia
GAMES
PROBLEM
SOLUTION
All Data East pinballs
You have been using some of the
150 watt "computer-type" power
supplies, in your video games.
The problem is that there is no +5
volt adjustment, and these units
average a 4.8 volt output. This
causes problems with some
games, especially those with a
loss in voltage through the 5v
feeds ( or ground).
Depending on the particular
''brand" you are using, odds are
the system uses a TL-494 or
equivalent PWM IC as the regu-
lator. If this is so and you have a
schematic available, look at the
voltage divider that goes from the
+5Vdc output to the feedback in-
put of the IC. If you lower that
feedback voltage it will up the
output voltage.
SUBJECT
Dot Matrix Display
PROBLEM
No display activity, yet all oper-
ating voltages seem to be there.
POSSIBLE CAUSE
You may have a bad 10 watt 3.9
Kohm resistor (R14) on the
power supply board. Arnie
Aarstadt at Data East Pinball
helped me find this and says he's
seen this problem with regular
frequency.
Address Changes
Please use your account
number when updating
your subscription
information.
He also suggests using a 2.2
Kohm @5 watts instead of one 3.9
Kohm@lOw.
Your account number is a
five digit number found
on the top line - left side of
your address label, which
is affixed to your journal.
D
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609/662-1080
OR FAX
609/662-0537
G
LAW
#1406
Thank you!
A
MURPHY'S
.
?
If you do something
right once, someone
will ask you to do it
again.