How To Upgrade Williams WPC Pinball Games With NVRAM

Williams made great pinball machines, especially their System 11 and WPC games. Unfortunately though, the RAM chip in every single Williams games was soldered directly to the board. In this article, we'll discuss the steps necessary to upgrade a Williams WPC game with NVRAM.

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Do you have a video?

We get asked often enough if we have videos or step-by-step instructions for upgrading a particular machine / boardset. And frankly, we don't because everyone has different tools, a different level of experience and to be blunt, some people really shouldn't be attempting an upgrade themselves on a $200-300 board if they don't have a solid amount of experience under their belt.

That said, there are individuals in the arcade / pinball community have posted some videos showing upgrades & we have that available further down this post!

This is informational only. If you decide to upgrade your game, you assume all responsibility! Please see the CAUTION below.

Upgrading Williams WPC MPU's Is Not Easy

We have to note this here to save people without the right tools and experience from messing up their boards. Williams WPC MPUs have thin and fragile traces & unless you have the right tools and experience upgrading these circuit boards, you're very likely to damage the board.

Please take into consideration your level of experience and the tools you have (a temperature controlled soldering iron is a must!) before attempting to upgrade your MPU. We will not be responsible for botched upgrades and if you cannot troubleshoot yourself you'll have to send your board out for repair.

Where People Run Into Problems

Sometimes we get emails from customers that installed one of our NVRAM Battery Eliminators and their game no longer works. It's unfortunate to hear of any installation issues, but it happens because on Williams games the installation isn't just a plug-and-play type of thing. Williams boards require removal of the existing RAM on the board and installation of an IC socket.

Where people usually run into problems is they had a working game, they remove the RAM chip using a desoldering gun or by cutting the legs of the chip and removing the pins. Then without checking each of the through-holes on both sides of the board and the traces at the through-holes, they solder in the IC socket, install the NVRAM and put the board back in the machine.

The problem with doing this is if you haven't properly cleaned the flux from the board after desoldering the RAM chip and haven't inspected the through-holes and traces at the through-holes, once you install the IC socket you cover up areas where the problem could be.

One Missing Signal = Board No Workie.

It takes just a single missing signal or shorted signal at the RAM chip to prevent the board from booting. And a non-booting board, is a dead game! So please take your time when upgrading, clean off the flux after you've desoldered the original RAM chip and cleared the through-holes, and inspect the through-holes and traces at the RAM chip footprint BEFORE soldering in an IC socket. You'll save a lot of time this way!

Tools Needed

  • Phillips-Head Screwdriver
  • Temperature Controlled Soldering Iron
  • Hakko Desoldering Gun
  • Solder with flux that is meant for board work
  • Tweezers
  • Micro Flush Cutters

Basic Outline Of Steps To Upgrade

  1. With the game powered off, disconnect all of the harnesses/plugs from the MPU board.
    *It's a good idea to take a few pictures before disconnecting anything to refer to later.
  2. Remove screws that are holding the MPU board in-place and remove the MPU board from the machine.
  3. At your workbench, add some solder to each of the solder joints of the RAM chip (back of the board) so that new flux is added. This makes desoldering a bit easier because solder flows better.
  4. Use a Hakko desoldering gun to clear each through-hole. Note that if you're not able to clear through-holes and free the leg of each pin, the through-hole can be damaged if attempting to pull the chip out while the legs are still attached with solder.
  5. As an alternative to the above, you can cut the legs at the RAM chip near the black plastic body of the RAM chip with micro flush cutters, then use a soldering iron to heat up the solder joint and tweezers to remove each leg from the top-side of the board separately. You can then add a bit of solder to each through-hole again and then use the desoldering gun to clear the hole fully.
  6. Clean up all flux from the front and back of board using flux cleaner or 99% isopropyl alcohol.
  7. With a magnifying glass, inspect traces at through-holes and the through-holes themselves for any damage from the desoldering process. For anything that looks suspect, confirm the connection via continuity test on a multimeter (test from the through-hole to the component the trace leads to).
  8. If you really want to be sure the upgrade will be successful, take your time and verify the connection from each through-hole for the RAM to the component it connects to. Use the WPC schematic from your game's manual and identify pin #1 on the RAM and which chip/component and pin # on that component it connects to. Then use your multimeter on continuity test to ensure you get a beep indicating continuity.
  9. Once you've cleaned up flux and inspected / verified the connections at the RAM footprint, it's then time to solder in the new IC socket.
  10. If you did not use no-clean flux, you MUST clean up the flux on the back of the board again after installing an IC socket. If after you clean the flux, it's still sticky or looks messy, keep cleaning! Use paper towels or a rag to blot up the worst of the flux, and clean again until the board looks nice!
  11. Inspect the solder joints to ensure they look good.
  12. Finally, reinstall the board in your game.

Duncan from Arcade Crusade Showing An Upgrade Of A Williams WPC MPU

As we mentioned earlier, we don't have videos showing an upgrade, but luckily some of our customers have been kind enough to create some videos for the community.

This is probably the best video out there showing all of the PROPER steps necessary to upgrading a WPC MPU. Note that Duncan has both a Hakko desoldering gun and Hakko temperature controlled soldering iron.

Similar Steps For Other MPUs

Although this article focuses on Williams WPC MPUs, the steps are the same for any MPUs that require desoldering of a RAM chip and installation of an IC socket. The only difference is the location of the RAM chip on the board and the size of the IC socket.


If you have problems after upgrading the MPU, unfortunately there's only so much we can assist you with diagnosing your board. We have a NVRAM Troubleshooting Guide you should refer to BEFORE contacting us to help walk through some steps to diagnosing your issue further.

95% of the time or more if a customer had a working game and it no longer works after an NVRAM upgrade, the issue is a missing signal or a short on the board. For games with thin traces or pads that don't put up with a lot of heat, like WPC, the issue is OFTEN that a pad or trace was damaged during desoldering.

Again, we highly encourage you to both clean up the flux and take the time to inspect solder joints and traces at the RAM footprint BEFORE soldering in an IC socket. It becomes MUCH more difficult trying to diagnose an issue after you've soldered in an IC socket that covers up some of the traces and through-holes.

Board Repair Recommendations

If you do need someone to help repair your board or perform an NVRAM upgrade in the United States, we recommend Chris Hibler @ Just be aware that his backlog of board repairs can often run several months since he's good at what he does and has a lot of customers.

In Conclusion

NVRAM upgrades that require soldering are not for everyone. We highly recommend that before you attempt an upgrade for yourself, you get the right tools & also get some experience under your belt by practicing on junk boards.

Williams WPC MPUs are more difficult to upgrade and this is why we have rated their difficulty as HIGH on your product pages. We sure hate for people to mess up their boards and then have to send them out for repair. It's easier to advise everyone upfront of the difficulty of the upgrade because many individuals will be better off having a professional with the right tools and experience upgrade their boards for them.

Check out our selection of NVRAM modules for pinball / arcade machines!

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