Battery Leakage on Solid State Pinball Boards: How to Spot It and Prevent It
If you own, or are thinking of buying, a solid state pinball machine from the late 1970s onwards, battery leakage is one of the first things to understand. It is quiet, slow, and can do serious damage to the board that runs the entire game.
This guide explains why it happens, how to check for it, the usual ways owners prevent it, and when damage needs a professional. It is written for owners, not board technicians, and it errs on the side of caution.
- Many solid state boards hold batteries to remember settings, audits and high scores. When batteries age, they can leak alkaline residue that corrodes traces, sockets and components.
- Check now: with the machine unplugged, look at the CPU board for green, white or blue crust around the battery holder and nearby parts.
- The common fix is a remote battery holder, which moves the batteries off the board so any future leak can't reach it. Other options exist depending on your board.
- Corrosion that has already spread needs proper neutralising and repair. Board repair is a skilled job; consider a specialist.
Why pinball boards have batteries
Solid state machines store settings, coin and play audits, and high scores in memory that loses its contents when power is removed. To keep that memory alive while the game is off, many boards include a battery pack, often a set of standard AA cells in a holder mounted directly on the CPU board.
The design made sense when the games were new and regularly serviced. Decades later, batteries are often left in place far too long, sometimes in machines that sat in storage for years.
How leakage damages a board
As alkaline batteries age, they can leak a caustic residue. On a circuit board, that residue attacks copper traces, the plating in through-holes, IC sockets, connector pins and component legs. Corrosion can creep under the board's solder mask and spread well beyond the visible stain, sometimes reaching nearby chips and connectors that are critical to the game working.
| What you see | What it may mean |
|---|---|
| White or crystalline crust on the battery ends | Batteries have leaked or are starting to |
| Green or blue discolouration on copper or pins | Corrosion has reached the board's metal |
| Dark or bubbled traces near the holder | Corrosion under the solder mask |
| Corroded IC socket or connector pins | Damage may cause intermittent or failed boot |
| Game won't boot, resets, or has odd faults | Possible corrosion damage, among many other causes |
A board can look fine from a distance and still be corroding. Inspect the battery area directly, with good light, even if the game plays perfectly today.
How to check your board
- Switch off and unplug the machine. Wait as your manual advises before handling boards.
- Open the backbox and locate the CPU or MPU board. The manual will show which one. Look for a battery holder or pack.
- Inspect with a bright light and a magnifier. Look at the battery ends, the holder contacts, nearby traces, chip sockets and connector pins.
- Photograph what you see for your records, and to share if you need advice.
- If batteries are present and showing any residue, remove them promptly, wearing gloves, and dispose of them properly.
Note: some boards use a different backup method, such as a soldered-in rechargeable cell or a non-volatile memory replacement. Check your manual and the board itself before ordering anything.
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Prevention options
Batteries live in a holder mounted away from the board, connected by wires. A leak can't reach the electronics.
Keep on-board batteries but replace them on a schedule. Lowest effort, but leaves risk on the board.
On some boards, a memory replacement removes the need for batteries. Board-specific.
Some owners use other approaches suited to their board. Ask in a platform-specific community.
Remote battery holders
This is the most widely recommended approach for owners who want to keep battery backup. The on-board holder is removed, and a holder is connected by wires and mounted somewhere safe, such as on the backbox wall, below the board. If those batteries ever leak, the residue drips onto wood, not electronics.
Installing one usually involves removing the original holder and soldering the new leads in place, observing correct polarity and any components in the battery circuit. It is a straightforward job for someone comfortable soldering on old boards, and a reasonable first board project for a careful learner. If you have never soldered, practise on scrap first or have a technician do it. Many board specialists offer it as a simple service.
Replacing batteries on schedule
If you keep on-board batteries, use fresh, good-quality cells and replace them regularly rather than waiting until they're flat. Mark the install date on the holder. This reduces, but does not eliminate, the risk.
Removing batteries may wipe your settings and high scores on some boards. Write down any custom settings first, or follow the manual's guidance on swapping cells while the game is powered, but only if you can do so safely and the manual supports it.
When corrosion is already there
Light residue on the battery ends with clean board metal is the best-case scenario: remove the batteries, clean gently, inspect carefully, and install a remote holder.
Corrosion on the board itself is different. The residue must be neutralised and removed, and damaged traces, sockets, connectors or components often need replacing. Corrosion can keep spreading if it is not fully treated. Board repair involves desoldering, trace repair and testing, and done badly it can make things worse.
- Minor corrosion limited to the holder area: a competent hobbyist with soldering skills may handle it.
- Corrosion reaching chips, sockets or connectors: consider a board repair specialist.
- Severe damage: some owners choose a replacement or aftermarket board instead of repair. Compatibility depends on your platform; check before buying.
Replacement boards exist for many popular platforms, but availability and compatibility vary. Search by your board type, not just the game title. Browse pinball MPU and CPU boards.
Checking battery condition before you buy
For any solid state machine, ask the seller for a clear, close photo of the CPU board battery area. It is one of the most revealing photos you can get.
- Are batteries on the board, remote-mounted, or absent?
- Any crust, staining or discolouration on or around the holder?
- Any signs of previous board repair, such as new sockets, jumper wires or patched traces? These are not bad in themselves; ask what was done.
- Does the game hold settings after being switched off?
Battery damage can affect value and repair costs. When researching value, compare completed sales of machines described as working with machines described as having board issues. See completed solid state pinball sales.
FAQ
Do all pinball machines have batteries?
No. Electromechanical machines don't, and solid state machines vary. Many from the late 1970s through the 1990s have batteries on the CPU board to keep settings and scores; some later games use other methods. Check your manual and the board itself.
How do I know if my pinball batteries have leaked?
With the machine unplugged, look closely at the battery holder and the board around it. White crust, green or blue discolouration, or dark, bubbled traces are signs of leakage or corrosion.
What is a remote battery holder?
It is a battery holder connected to the board by wires and mounted away from the electronics. If the batteries ever leak, the residue can't reach the board.
Will removing the batteries erase my settings?
On many boards, yes. Write down custom settings before you remove them, and re-enter them afterwards.
Can battery corrosion be repaired?
Often, yes, depending on how far it has spread. Light corrosion can be cleaned and repaired by a skilled hobbyist; heavier damage usually needs a board repair specialist or a replacement board.
The bottom line
Battery leakage is one of the most avoidable forms of serious damage in pinball. Inspect the CPU board now, remove any aging or leaking batteries, and move to a remote holder or another safe backup method suited to your board. If corrosion has already spread, get it treated properly before it gets worse.
Buying a solid state game? Add the battery photo to your questions, alongside those in our eBay buying checklist.