<disclaimer>

This is not intended to tell you what to do. Simply to provide suggestions. It seems to me that there has been a lot of random things. You cannot reliably find problems by randomly trying things. You must be systematic.

</disclaimer>

• Start with the Pinwiki. Read https://www.pinwiki.com/wiki/index.php/Williams_WPC#Switch_Problems for information.
• Differentiate between board and wiring. Specifically https://www.pinwiki.com/wiki/index.php/Williams_WPC#Switch_Matrix_Problems for reference.
• If you're still confused then empty all the balls and post an image of the switch matrix. Images are better for those trying to help because descriptions are not always accurate or convey the appropriate information.

Yes. The eliminates the CPU board. You can absolutely isolate the problem to the 7-opto board by testing switch 37 and 38 in the switch edge test. These should register.

Yes. The output of the comparator is placed directly on the switch matrix wiring. The test simulates the situation where the phototransistor has IR light falling on it. This creates a voltage that is detected by the comparator.

This indicates that there is power at each of the pins for the IR LED. It does NOT actually test the IR LED is emitting IR light. These IR LEDs are driven hard and if they are original (never replaced) then there is a good chance that they might have failed. However ... all seven failing is extremely unlikely.

In all likelihood there is a problem on the 7-opto board. You could replace both LM339s but if you want to surgically replace the most likely IC that has failed you should replace U1. Unit B of the comparator is the column and is a potential single point of failure.

opto7_schematic.jpg

If you are comfortable with board work this is the cheapest option. If you do not have de-soldering equipment you can cut all the legs of the IC, remove the body and then remove each individual leg. Clean out the holes. Install a socket. Install a new comparator. Test again.

If you intend to replace the entire board there are various merchants that sell boards from various manufacturers.

I also have a board available that I would be only too happy to sell you.

This leans potential diagnosis in the direction of broken wire / connection. Since you verified the CPU board using the Pinwiki testing procedure you can verify continuity from the column wire in the connector to the 7-opto board and switches 37 and 38. There should be a break in the connection. You can test the physical switch for continuity using a DMM.

Do the above check first. The board should be the last thing you should touch unless you have conclusive proof that the issue is on the board. The lack of switch 37 and 38 registering in test means the evidence is not conclusive.

If you are looking for a replacement board you have these options (at the very least):

• Pinball Electronics from barakandl: https://nvram.weebly.com/wpc-7-opto-switch-a-15595.html
• Pinball Life sells the Anarchy board: https://www.pinballlife.com/mm5/merchant.mvc?Screen=PROD&Product_Code=A-15595-1
• Pinball Haus sells the Homepin board: https://pinballhaus.com/shop/pinball-boards/miscellaneous-boards/7-opto-board-a-15576-a-14977-a-15595-bally-williams/?v=7516fd43adaa
• Pindora Box sells their own board: https://www.pindorabox.com/product/opto-board-7-switch-assy

All the above boards appear to be based on the original design of the Williams 7-opto board. The board from barakandl spreads the heat load across multiple resistors whereas the other boards all use the 2W resistors that dissipate a LOT of heat. If I were to choose one of the above merchants I would choose the barakandl board. Pinball Haus and Pindora Box are not located in the continental US so you will likely face higher shipping charges from them.

My board is available bare for $30 or complete for $60 (pricing is valid as of posting). Shipping is extra. It is a different design and more akin to the Great Lakes Modular boards that were available years ago. It reduces the drive voltage (reduces heat dissipation), uses discrete transistors rather than a comparator and has LED indicators. Image of the board is @ https://pinside.com/pinball/forum/topic/dumbass-test-and-reproduction-pcbs/page/4#post-5867818. Please use PM if interested.