Products >> Pinball Diagnostic Tools >> WPC Reverse Switch Tester

WPC Reverse Switch Tester

This is a handy diagnostic tool that plugs into J207/J209 on WPC MPUs and allows you to easily test for some common diode issues on WPC playfield switches like reversed or shorted diodes and can even help with diagnosing phantom switch closures.. potentially saving hours of troubleshooting over and over again.

How It Works
What it does is simple, but very effective. This small board reverses the column and row signals by re-routing columns to rows (and rows to columns). You piggyback the playfield harness into this board, which is connected into the J207/J209 headers on the MPU board. Why do this? Well, when utilizing WPC's Built-In "Switch Edges" test (part of the diagnostics menu), it then allows you to troubleshoot a number of issues with switch diodes that would otherwise be pretty difficult to track down on their own.

Can be useful in catching the following:

  • Reversed diodes (switch will show active when closed)
  • Shorted diodes, including short of diode lead at switch lug (switch will show active when closed)
  • Column ground shorts (reported as "GND SHORT ROW#" during Switch Edges test)
  • Row ground shorts (reported as "GND SHORT ROW#" during Switch Edges test when switch is closed)

Usage Instructions

With the machine off, disconnect any opto boards under the playfield. Some games may have multiple opto boards.

Next, from inside the backbox, unplug the playfield wire harnesses from J206/J208 (or J207/J209) on the MPU and plug in the WPC Reverse Switch Tester board at J207/J209 headers. Plug the playfield harnesses into the tester board. Turn on the machine and enter Diagnostic Tests via coin door buttons. Navigate to TESTS -> Switch Edges. No switches should show as active here (except SW24 if cabinet switches at J212 are left connected). If you get a fuse error when turning on the game, you may have to first boot the game without the Reverse Switch Tester board connected.. then once in Switch Edges test, you can install the Reverse Switch Tester board.

If any switches do show as active immediately (except SW24 if cabinet switches at J212 are left connected), they would either be switches that are closed and have a reversed/shorted diode (ie. NC switches or switches that are misadjusted and closed when they shouldn't be -- that also have a shorted/reversed diode). You could also see a "GND SHORT ROW#" error if a column line is directly shorted to GND -- it will be indicated as a row short since the column & switch lines are reversed.

If there aren't any immediate switches showing as active, you can then work through other switch issues you were having. Normally you will have experienced a non-working switch.. or scenario where you get a phantom swith closure. Manually triggering switches with the tester board connected will allow you to identify the problematic switches/diodes further. No switches should show as active when they're manually triggered, any that do likely have a shorted or reversed diodes.

Scenarios This Board Can Help With

  • Row short to GND
    • Without the reverse board = "GND SHORT ROW#" during Switch Edges
    • With the reverse board = nothing
  • Column short to GND
    • Without the reverse board = nothing
    • With the reverse board = "GND SHORT ROW#" during Switch Edges
  • Diode shorted on a switch
    • Without the reverse board = Active when switch is closed
    • With the reverse board = Active when switch is closed
  • Reversed diode
    • Without the reverse board = Switch will not show as active when closed
    • With the reverse board = Active when switch is closed
  • Phantom Switch Closure
    Example: SW22 diode shorted; SW22, SW24 & SW32 activated
    • Without the reverse board = SW34 goes active (ie. phantom switch closure occurs)
    • With the reverse board = Only SW22 would read as active (ie. shorted diode identified)

Board is very compact, measures 2.13in x 0.67in so will have no trouble fitting in your toolbox!


Option #1: DIY KIT - $10.00 each

This is a bare board and the PCB components necessary to build the board. Requires assembly and soldering experience. This is for DIY'ers that want to save a few dollars by assembling the tester themselves. Limited Assembly Instructions.

Option #2: Fully Assembled - $15.00 each

Fully assembled & tested board, ready to go.

Availability: PLEASE INQUIRE

  This item ships only to United States, Canada & Australia

ASSEMBLED "Pinitech" PCBs are manufactured in the US and are currenty only shipping to the United States, Canada & Australia.
DIY Kits and Bare Boards may be available to other international customers. See below for details.

Australia, Canada Customers:
There is a minimum order of $25 (before shipping) due to higher international postage costs. Orders exceeding $400 or 4 pounds in weight must ship Priority Mail International & you will be contacted if additional shipping costs are due. Full order value is declared on customs declarations, no exceptions.

Other International Customers:
We do not currently ship assembled pcbs to EU at this time. Paypal is configured to accept only orders from United States, Canada & Australia.

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