12
STAR*TECH JOURNAL/MAY 1982
Led & Tone
Board Problem
On
1 & stop
ZPU or power board
ZPU (Rom error)
2 & stop
ZPU (Ram error)
3 & stop (or keep flashing)
4 & stop
5 & stop
VFB
6 & stop
VFB (Alu or Interceptor)
ZPU (NMI or Interrupt)
Powered up
7 & stop
8 & stop
BSC
VFB (Shifter/Flopper)
Entering the power-up self test can also be
accomplished by pressing the reset switch on the ZPU.
The results of this test are generally reliable,
particularly if it gets past the first test. In addition to
the power-up test, there are also a couple other
diagnostic tests built into "Frenzy". There is a switch
test which can be entered into by placing switch 3 on
dip bank 1 to the on position and pressing the reset
switch. A visual display of all ZPU dip switches and
game input switches will be displayed on the monitor.
A monitor alignment test also exists and can be entered
into by placing switch 4 on dip bank 1 to the on
position and pressing the reset switch. A cross hatch
pattern will then be displayed for monitor alignments;
pushing the fire button will cause a red screen to check
purity.
Troubleshooting
Take note that the +5 volts is especially critical, and
that it is adjustable, even though the LM323 is usually
employed as a fixed +5 volt regulator on most other
power supplies. The best place to measure this voltage
is at TP4 on the VS-1000. It must be adjusted between
+5 VDC and +5.25 VDC. The principle failures on
the power supply will most likely be cracked or cold
solder connections on C 1 and C2, the large filter
capacitors. Occasionally these capacitors will become
leaky and occasionally a packaged regulator will go
bad.
3. If voltages appear good, then check for broken or
loose ribbon cables (keeping a spare ribbon cable in
the bottom of the game or in your tool case might
not be a bad idea).
4. Check dip switch settings for proper operation. (The
dip switches on ZPU, VFB, BSC, and SB-1000 have
settings for signature analysis, and if improperly set,
will cause the game not to fully power up.) Keeping a
piece of paper with proper dip switch settings written
down may save an unnecessary board exchange.
5. If the failure is not with the sound, then disconnect
the ribbon cable to SB- I 000 and power cables to
VSU-1000 and SB-1000. These boards could
possibly load down a voltage, cause a fuse to blow,
or otherwise cause the game not to power up. By
disconnecting these boards, you can either eliminate
them as the source of failure or isolate them as the
cause of the problem.
You're given a service call for a broken "Frenzy".
You're driving a small foreign economy car with a
small trunk that barely has enough room for all your
tools, let alone an entire "Frenzy" sliding drawer. The
pressure is on, the failure must be isolated, at least to a
specific board. Can this be done? Yes! With a
voltmeter and utilizing the game's built in self test,
many failures can be directly repaired or at least
isolated. Certain procedures can be especially helpful.
These procedures should help to isolate any failure on
a "Frenzy" tray, thus making it possible to just replace
the bad board instead of pulling out the entire tray.
There are only a few occasions when the entire tray
need be removed for test. This would occur on the very
infrequent occasions when you would replace the board
indicated as bad by the led on the ZPU board, and the
same problem still exists. Also, with any intermittent
problems, it probably is best to have the entire tray
tested.
1. Check the power up (led on ZPU board for
indication of the bad board.
Conclusion
2. If led comes on and stays on, check all fuses and
measure power supply voltages.
TEST POINT (on PS-1000)
TPI - + 5 VDC
TP2- - 5 VDC
TP3 - +15 VDC
TP4- +12 VDC
TP5-
GND.
000000000000
While "Berzerk" and now "Frenzy" may seem
extremely complex compared to the single logic boards
used in most games, the self test should help alleviate
most of the indecision or confusion brought about by the
large number of boards. The principle advantages of
"Frenzy" are that any mechanic who has a basic
understanding of "Berzerk" already knows this system
and does not need to learn a new one. In addition, any
board repair shop already possessing a "Berzerk" test
set-up is already prepared for "Frenzy". The
comparisons/differences between "Berzerk" and
"Frenzy" listed in this article were primarily
mentioned to aid in troubleshooting "Frenzy". Using a
similar electronic system as Stern has with "Frenzy"
would make things easier for all service personnel, but
is unfeasible because of game conversions.