How To: Arcade Machine Repair

Arcade RepairOn first inspection, repairing an arcade machine that is not functioning correctly or is completely dead might seem like a bit of a challenge. There are PCB boards, plenty of wires and a general feeling of unfamiliarity for anyone more accustomed to repairing say a PC. Still, this is no reason to stop you trying to fix what is most likely a reasonably expensive machine, and if you are anything like me it can become a bit of a hobby!

Firstly, a disclaimer: Some of the tips I’ll be sharing today include checking mains voltages, so if you are unfamiliar with working with mains voltages I’d definitely advise you ask a qualified electrician to check these areas for you – we want to fix your arcade, not get you electrocuted!

Now that’s out of the way, let’s take a look at what’s wrong with the machine and how we can fix it. Today I’ll be focusing on Jamma-based arcade machines (more on what a Jamma arcade is here). As these are some of the most common types of cabinets in people’s homes, it seems a fair place to start.

If you have a specific problem, here are the issues I am looking at today – click to go straight to the answer:

Problem: Machine completely dead (no sound, no video)

I’m going to address this problem, by breaking it down into separate sections:

Outside the machine

  • Outside the arcade machineIs the machine actually turned on? Many arcade machines have what is generally referred to as a ‘rocker’ switch, normally next to where the power cord plugs into the machine. These can be hard to see, and even harder to tell which state (on/off) they are in – so first of all check to see if this switch is set to the off position. Sounds simple, but you’d be surprised how many times this can turn out to be the issue.
  • Does the plug socket the machine is plugged into work correctly? Try the machine with a known working socket.
  • Check the mains lead. (Note: this may not apply to older machines as they may simply have a lead going straight into the back) If available, try another mains lead – normally these are the ‘kettle lead’ Euro plugs (at least here in the EU they are!), so finding one to borrow for a minute shouldn’t be too hard.
  • Check any fuses that are accessible on the back of the machine – these can be found near where the mains lead plugs in, and near to where the ‘rocker’ switch will also be. Use an ohmmeter to check the fuses are functioning correctly. If you don’t have an ohmmeter available, you could try replacing the fuses to see if that helps matters. However please note that these fuses are not likely to be the same ones you have lying around your house, they vary by machine and come in many different sizes and types, so it’s more likely than not that you won’t have a spare compatible fuse (that’s not to say you can’t go buy one though!).

Inside the machine

If none of the above was the problem, then we know that power is getting into the machine, so we need to get into the machine ourselves to try and diagnose what’s going on in there.

  • Inside the arcadeFirst off, check to see if there is a ‘door switch’ – this is a switch that cuts the power to the machine when the doors (back and sometimes front) are opened. If you are doing any of these internal tests, the switch will need to be in the ‘closed door position’. You may just have to wedge this shut, or push it in/pull it out – there are different types, but basically it needs to think the door is shut when it’s not.
  • On the machine side of the plug (or the end of the mains lead if it’s the permanently connected type) check to see if there is a mains voltage [Warning: This is live voltage people!]. Use a voltmeter set to AC, using a suitable voltage range to see if there is power making it into the machine. No power coming in could mean there is an issue with the socket where the mains lead is plugged into, or you may need to double check the external factors listed above.
  • If there is power coming into the machine, we need to be sure that the power goes from here to where it is needed. From here the power usually splits off two ways: first to the game side of things, and second to the monitor side of things. Let’s deal with these separately.

Game side

  • PSU and JAMMA ConnectorThere should be a power supply unit, PSU, where the inbound power goes – this converts the power from AC to DC for use by the game board. We need to check that the PSU is doing its job correctly, so using a voltmeter set to DC, check the output terminals of the PSU.
  • Using the voltmeter you would normally see +5v, +12v and -5v measured between the ground wire (normally black in colour) and the different terminals on the PSU. These should be marked as red (or connected to with a red wire) for +5v, orange or yellow for +12v, and blue/violet for -5v. Of course your PSU could be different, but these are generally the standard colours.
  • If you can’t see these voltages coming out at all, or they are not at the above stated voltages, this could indicate a problem with your PSU and you should try another one if you have one available.
  • If your PSU is outputting correctly, use the voltmeter to check that the same voltages are on the Jamma connector – just to make sure there are no broken wires between the PSU and the game board. The Jamma connector is the long rectangular plug that plugs into the game board.
  • Ensure the Jamma connector is properly connected to the game board – some Jamma connectors will have one pin blocked out of the plug to ensure it can only fit one way (as the Jamma connector has one pin missing to help guide you). If yours doesn’t, make sure it isn’t one pin down from where it should be.
  • If you have checked all of the above and still aren’t having any luck, it could well be your game board that has a fault. These unfortunately aren’t really user-serviceable, but can be repaired by professionals. If you have another Jamma board to hand, give that a try and see if the machine works with that board.

Video side

If you are in the UK, the EU or pretty much anywhere that uses 240v rather than 110v, we have a potential extra step we need to check first. There could be a transformer in place between the 240v power-in and the monitor, if the monitor is 110v. To verify, follow the wire from the power input to the monitor and if there is a box in between, you have a transformer and need to check this first.

To do this, just use a voltmeter set on AC to check that the input and output voltages are as expected.

  • Monitor Chassis ConnectorCheck the video input plug from the game board to the monitor. This can take several forms, from a more modern VGA style connector, directly through the Jamma connector (although I haven’t seen too many like this), or through a generic ‘plug’ with red, green, blue (for the colours), black (ground), white (composite sync) and possibly yellow (horizontal sync) wires. Ensure either of these are plugged in correctly, as with moving the machine or some spirited play they can become loose over time.
  • If you have an older style CRT monitor, check if there is a glow inside of the tube. No glow? Then most likely the monitor is faulty – well when I say monitor it is more than likely to be what is known as the ‘chassis board’, which is pretty much the brains of the CRT. If it’s an older machine then it could potentially be the tube that has gone. Although these generally go gradually so you would notice (unless the machine has been standing around unused for a very, very long time).
  • If you do see a glow, check that the brightness control is turned up high enough to get a picture.
  • You can always check with an alternative compatible monitor if one is available. Just be sure that the alternative monitor is compatible with the output signal that the board is giving you.

Problem: Sound but no video

If the machine powers up and you can hear the game playing, but you can’t see anything on the screen, just follow the above guide from Video side down.

Problem: Video but no sound

  • Speaker ConnectorsFirst off, check the volume control on the game board – it could be possible it’s turned all the way down (again, sounds simple but you’d be surprised how many times we hear of this problem!).
  • Check the wiring between the Jamma connector and the speaker (ensure the wire isn’t broken or has become disconnected).
  • If you have another speaker available, try connecting this to the audio output.
  • If none of these are working, then I’m afraid it looks like it might well be the amplifier on the board that has gone. Again these are rarely user-serviceable, but can be repaired by professionals.

Problem: Joystick / buttons don’t work at all

  • Arcade Button Ground WireIf none of your joysticks or buttons are working, then my advice would be to check the ground wire, normally a black colour. This wire is connected to each micro-switch (on the joysticks and buttons) and as it is a loop, if part of the loop is broken (especially on the first button), the whole lot could stop working.
  • Check that the other end of the black ground wire is correctly attached to the Jamma connector, as it could have come loose – again breaking the loop.
  • Check that the Jamma connector is inserted correctly.

Problem: Joystick not working in one direction / button not working

Nobody likes to have their tiger-uppercut fail due to a faulty button. If this is happening to you, check the following:

  • Arcade Microswitch ConnectorsAgain take a look at the black ground wire (on both ends), but also check the coloured wire attached to the offending button/joystick micro-switch. Make sure it’s properly connected to both the joystick/button and the Jamma connector (the Jamma connector has a wire for each micro-switch, with one ground wire connected to all micro-switches)
  • To test if the actual micro-switch inside the button/joystick could be at fault, connect the black ground wire and the coloured wire together. Do this whilst in a game, and the button should fire. If this happens, it’s time for a new micro-switch in that particular button or joystick (or just replace the whole thing if you aren’t happy replacing micro-switches – although watch out for an upcoming blog post on how to do this!).

Problem: Machine not accepting coins

Not all arcade machines are set up to take coins, many operate on ‘freeplay’ mode. But if yours is set up to take coins, and it’s not, here’s what you need to look at:

  • Arcade Multi Coin Mechanism ConnectorsCheck that the coin mechanism is correctly plugged in. Most modern coin mechs are multi-coin mechs; meaning they can take coins up to the value of the price to play, rather than just the one coin, whereas older mechs worked on a micro-switch basis. If you have a micro-switch based coin-mech, joining the two connecting wires together while the game is in attract mode should simulate inserting a coin into the machine – and prove you need a new mech.
  • Multi-coin mechs are powered by a +12v supply. If it is marked on the side if the mech which pins are which (ground and +12v), you can use a DC voltmeter to ensure the coin-mech is receiving power. If there is no power going to the mech, check the other end of the Jamma connector to see if power is flowing out – you could have a faulty wire.
  • If none of the above works, try another coin mechanism if one is available.

Problem: No light in top marquee

Nobody likes a dark marquee top – it’s one of the most iconic parts of the arcade machine and if yours has gone dull, perhaps this could help:

  • VoltmeterOlder machines would have a fluorescent light coming straight from the mains, so check the voltage with an AC voltmeter. If the voltage going to the light fitting is good, try another tube/bulb.
  • Newer machines (most that I have seen anyway) have a 12v cold cathode tube to illuminate the marquee. This 12v will most likely be coming from the same PSU that powers the game board, so assuming the game board is working, check that there is 12v going to the cathode tube. If there is, it might be time for a new one. Although the tube comes complete with a 12v inverter, and this normally requires swapping them out as a single unit.

So there we have it. Hopefully by now your arcade machine will be back to doing what it does best – playing games. If you are still having problems, drop a note in the comments and I can try my best to help.


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