Pinball Rehab

pinball repair and restoration

Pinball Mods - Read Me First Pinball Mods - Read Me First Hot

The purpose of this article is to help prevent the all too common problems caused by pinball mods that require a power source (typically 5 volts or 12 volts).  While a few manufacturers of mods may test the mod to ensure it doesn't overload a pinball circuit and provide accurate installation instructions, the majority don't.

In fact the majority of powered mods leave it up to the installer to decide where to connect the power inputs.

Just to be clear, problems caused by mods are frequently posted on pinside.com.  They are not a rare occurrence and you can't assume the person who designed the mod knows what they're doing.

Even in cases where a single mod would not be a problem I've seen people put multiple mods on the same power source and blow bridge rectifiers or other components.

Overloading Circuits

If you overload a circuit in your house you blow a fuse.  Unfortunately on a pinball game you're apt to fry a few components before the fuse blows.  Combine that with the fact that most pinball power circuits do not have a lot of leeway in regards to handling increased current and you have a recipe for disaster.

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Pinball Mods - Read Me First

Unfortunately to accurately determine how much additional current draw a circuit, or sub-circuit, can take (especially on a 20 some year-old game) is not easy.  I will skip all of the technical stuff, but trust me that when components in a circuit blow before the fuse does it requires some pretty good electronics knowledge to determine how much current a circuit will safely take.

I will though go out on a limb and give some general guidelines.

  1. If you're adding an LED or two to a circuit there probably won't be any problem since they draw so little current.  The same is not true of LED strings.
  2. If you convert existing bulbs to LED's you will decrease the current draw on that circuit, and only that circuit, enough to give a moderate safety margin for mods.
  3. Most GI circuits are under-designed (hence all of the burned GI connectors) so I would not add anything to a GI circuit unless the existing bulbs where first converted to LED's.
  4. Be very cautious of EL (electroluminescent) products like the NoFlix Pinball Card.  EL products require an inverter and draw a lot of current (almost 1/2 amp per card in the case of the NoFlix).
  5. The same applies to any motorized mods.

Also be aware that some high-powered LED's can draw almost as much as a bulb so they don't provide much benefit.

You can test a circuit by removing one side of the fuse and then use your DMM to measure amperage.  Do this test while in game mode to get the maximum load on the circuit.  After installation of the mod you want a 25-33% safety margin (i.e. - If the fuse is a 3 amp, no more than 2 amps current draw for a 33% margin).

Note: This is only a rough test.  Even though a circuit may be rated at 2 amps, parts of the circuit (components, traces and wires) will be rated much lower than that.

My final suggestion would be to search on pinside.com and see what problems people may have had with the mod.  You can also post and ask for suggestions about where to connect the mod.  Be aware though that I have seen some very bad advice (even from people with a lot of karma).

Installation Instructions

I recently installed the Uncle Fester mod on my Addams Family and the instructions where to put alligator clips on the power and ground test points on the Driver Board (see Image 1 of another mod that shall go unnamed).  This is an exceptionally bad idea and will most likely eventually result in bad things happening when the clip vibrates loose.

I should note, anytime the mod includes alligator clips it's a pretty good sign the manufacturer of the mod does not know what they're doing.  I would therefore be extra cautious with any of their mods.

While it is best to splice and solder the connections, it is acceptable to use a quick splice connector.  Also route the wires along other cable bundles and use wire ties to attach.  This will prevent loose hanging wires from being caught on something and pulled loose or stressed.