1. Completely dead game. If the game shows some sign
of life then Go to (2).
A) Before you start, check for the obvious. Check plug
wiring and fuse. If there is plug to the game, is it properly seated? Are all
plugs seated in the game? Is there a power switch on the cabinet that has been
switched off? If there is a door operated switch, push in the button by hand to
see if game comes on. Sometimes the door wont push this in far enough.
B) Next look for burnt plugs or dry solder joints
especially where plugs are soldered directly on to the boards. If the solder
has dried or cracked around power plugs on the boards, the game will not power
up. Re-solder these and any other suspect joints.
C) If the main fuse keeps blowing in the plug, check the
suppressor hasn't shorted out by unplugging the game, disconnecting the wires
and checking with a meter across live and earth and live and neutral. The
suppressor is usually a small aluminium can screwed the cabinet
D) The only other things to check on the power side is
the fluorescent lamp and possibly the isolation transformer for the monitor.
Disconnect the lamp power and try the game. Isolate the monitor transformer
power and switch on. The monitor should have its own fuse, but you can try
disconnecting the power plug from the monitor to see if this helps. If the game
still refuses so show any signs of life, check the cabinet wiring diagram for
anything unusual and use a meter to see how far the power gets to try and
isolate the fault.
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2. Fluorescent light is on or power present, but no
picture.
If there is no light or obvious signs of life, you will need to determine that
the mains is at least reaching the power supply or monitor transformer using a
volt meter. If it is not go back to Section 1.
Put a credit on the game and press the start button. Can the game sounds be
heard? If the answer is yes, then the power supply and the game board are
functioning which points to faulty monitor. Go to (E). If the
answer is no, this points to either the power supply or the game board.
Go to (F).
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E)This now looks like a monitor fault. You should not proceed unless you are familiar with monitor
safety procedures. There can be up to 25,000 volts present and messing around
even with the power off can be fatal. YOU
HAVE BEEN WARNED! See top of page for more information. If
you have a Hantarex MTC9000 monitor, a more detailed fault list can be found at
Hantarex.htm. If you have something obvious like a
horizontal line or a missing colour you can start there although specific
faults like this wont be covered here. Use the circuit diagram or seek the
services of a repair man. A dead monitor is not so clear cut. First increase
the screen brightness. Can you see a grey/white screen (raster). If the answer
is yes then the monitor is working and we have to suspect the logic board.
Go to (K). Look at the neck of the tube. Is there a faint
orange glow from the heaters? If the answer is yes then the monitor is
receiving power. Can you hear a high pitched noise and the build up of static
on the tube when you switch on? Take a mains testing screwdriver. Hold the
bladed end and hold the neon lamp end near to the EHT transformer. Does the
lamp glow? If the answer to any one of these is yes, this shows that the
monitor is receiving power and the EHT is working. Go to (G).
If not we have to look at the power section. Go to (H).
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F) Using a meter check power supply for +5V, +12V and
-5V where used. If this a newer game, you will only need the +5V to get a
picture on the screen. +12V usually just powers the sound amplifier. If you
have all the correct voltages present at the input and output of the power
supply, the the logic board is most likely at fault. Go to (K).
If you have no +5V or other voltages are missing you can suspect the power
supply. Go to (J).
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G)We have heaters and EHT but no raster. If you have
another working logic board, then try it. If the screen still refuses to show
anything, this could be any number of awkward faults. It would be better to get
the monitor looked at by a engineer.
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H) Use a meter to check that power is reaching the
monitor power plug. Check the monitor fuse. Remove or lift up the chassis and
look for dry joints especially around the power plugs, other connectors and the
base of the line output transformer. Re-solder any dry joints. If you have a
circuit diagram, check the power supply on the chassis. You should find a value
around 120V. If there is no voltage check the power regulator and the large
shunt resistor if used. If you still have problems Go to
(L).
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J) If you have got here I assume that main voltage is
present 120/240V, but some or all of the output voltages are missing. There
could be high voltages present, BE CAREFUL! Switch mode power supplies are
beyond the scope of this article, but you could check the components up to the
bridge rectifier that may have short circuited. If the fuse has gone with a
bang, you will need to find the problem before you replace it. The easiest and
cheapest option is to replace the faulty unit. Other power supplies can be
easier to fix depending on their complexity. Check all the fuses one by one.
Often a bridge rectifier or power regulator is all that needs replacing. Use
the circuit diagram to try and locate the fault. Any further help is beyond the
scope of this article.
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K) Suspected game logic board. First things first, make
sure 5V is set correctly and present on the board, not at the connector. If it
is missing, check the wiring between the power supply and the board. Check any
plugs between boards by removing and replacing them. Check all socketed ICs'
are properly seated by pushing down on them. Use the boards self test facility
if there is one to help try and identify any failed components. This is about
as far as you can go unless you can repair logic boards, in which case I doubt
if you need this article!
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L) Two other main failures are the LOPT and vertical
output transistor. The monitor hand book and circuit diagram will be useful
here. We can supply manuals for many monitors. Check the vertical output
transistor to see if it has shorted. Other low resistance components can be
connected across it, so remove it before checking with a meter. If the LOPT has
blown, the casing may often be cracked , swollen or melted. These have a
tendency to fail in Hantarex monitors. From here you are on your own, and may
need the services of your local TV repair centre or send the chassis away for
repair.
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3. Game OK, but no sound.
Check +12V on PSU and at the main board. This voltage is responsible for
running the audio amplifier.
Check wiring to speaker using a meter and any volume control used in line with
the speaker. You can check the speaker with a meter, it should read between 4
and 8 ohms.
Check to see if there is any sound output from logic board. Use voltmeter set
to 20V. It should move like a level meter on a tape recorder. If there is no
sound output, and the 12V is present, the audio amplifier on the main board
should be suspected.
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4. Controls not working.
If some or no controls are working, check ground continuity between logic board
and panel. This is the common wire that links all the switches together. There
should be no breaks in the line and it should be connected to Ground. 0V.
For individual controls, check switches with a meter and the individual wires
back to the PCB.
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