I doubt that the switches are bad, they are quite robust and easily checked with an ohmmeter.

More likely you have reversed diodes and/or reversed/incorrectly placed wires.

The correct diodes are IN4001, but most people put in the much more robust IN4007 ones.

Either will work perfectly.

Start reading here:

http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Switch_Matrix_Problems

You can trace the wires back to the connectors by color etc. or from the row and column connectors to the end points.

If the wire pairs are right, you can even briefly touch the ends together (make a switch jumper out of a couple alligator clips and a piece of scrap wire and clip onto a diode (banded side away from the clip) connect the empty clip to the white wire and touch diode lead to the other colored wire) to see the wires work properly in test.

You will also see that the matrix everyone talks about is real and is represented on the display screen.

one of the 8 pins on the row connector go to one each of the 8 pins on the column connector, there are 8 pins on each connector, 8 x 8 = 64 switch combinations

Rows and columns now begin to make sense in a real world experiment (they are labeled on the cpu board).

Playing with the cpu board and jumpers is fun and informative. Its low voltge and if you take care not to cross something with high voltage, relatively safe.

Now you have learned how to test the CPU pins, and then the wires for continuity.
All thats left is to wire the switch correctly.

It should help to light your way.

The lamp matrix is similar in concept.

Pop bumper switches are leaf switches. Simple metal to metal contact, old school.

The only way they wouldnt work is dirty contacts or broken off leaves. take a look at the one you replaced and you can check this out.

It very possible it just needed adjusting.

You will need to know how to do this in the future to keep the leaf switches working correctly. They need adjustments once in awhile.

Clean the contacts (on modern games) with rough paper like a crisp dollar bill or a little metal polish (the tiniest amount) like Flitz or simichrome.

Dont sand them.

Looks good so far, congratulations on making it this far. Are you going to turn the start button 90 degrees? That would bug the shit out of me.

Sounds like the wrong switch was sent to you.

Some have a resistor or even a capacitor or both (older games) instead of a diode.

Its Avant-Garde!

https://en.wikipedia.org/wiki/Avant-garde

How much have you spent on shipping alone so far? So many orders

no, the white wire (in your case) and the non-banded side of the diode are on the same lug, but the diode could be backwards.

But check your work on the drop targets. The non-banded side of the diode goes to the white (hot, higher potential) wire in your case.

Most likely you have backwards diodes, not bad switches.

If the diode is backwards the power stops there immediately and wont go thru the circuit.

To test, clip out the diode that may be backwards. test the switch and you will get activation on the screen, it wont hurt the game. You might get 4 activations, but this tests the switch. Then put the diode in correctly, and test again.

Leaf switches are very simple, single contact mechanical switches.

The key here is that the white wire (in your case) goes to the non banded side of the diode on all of the switches in the game.

Here is a pic from my non-restored game.
Note that the green wire on the lower millions switch has an extra pair of wires on the green wire connection:
millions switches 3 (resized).jpg

here is a pic if the lower millions:

20220909_132652 (resized).jpg

here is a pic of the upper 2 switches:

millions switches 2 (resized).jpg

I would start with the lower millions, get it working, and then do the other 2

solder sucker:

https://www.amazon.com/Desoldering-Vacuum-Large-Teflon-Antistatic/dp/B00KQAIXEY/ref=sr_1_10

you can use real copper scrubbing pads or pieces cut from them to draw off extra solder.
Put one in a tuna can or ashtray to clean your tip.

Must be real copper.

get them at the grocery store:

https://www.amazon.com/Chore-Boy-Copper-Scouring-Pad-2ct/dp/B006K3XS5A

I've never seen a diode fail. Wire may break, but the diode never fails.

The power version is something like this...

https://www.amazon.com/Hakko-FR-301-Desoldering-Tool/dp/B07BKSLLG9/ref=sr_1_3

Though the manual ones like linked above work just fine at a fraction of the price, albeit slower.

I was curious of what your switch matrix looked like, i.e. working row/columns.

For column 4, making sure the wire crimp at the board connection is good, then I would start with switch 41, and disconnect the green wire at 42. Get 41 working and work down the column the same way.
screenshot_1237 (resized).png

I rewarded myself with one of these last year, after years of using a manual solder sucker. Not sure why I waited so long (price...)

The manual ones are good for getting solder off coils and switches. If you're doing any type of board work the Hakko can't be beat. Hands down some of the best money I've ever spent in this hobby.

Send me all the brand new switches that you are throwing out please!

Great deal, Im in! (you dont even need to clean them)

Another way to remove solder from something is to heat up the solder then 'bang' the item on a table or board.
The solder will just fall off.

This method works well on switches.

Matt.

depending on the type of switch, it may not click, best to just check the switch operation with a multi-meter using the continuity mode of the meter.

The connector goes to a lug. The color of the wire will guide you.

trough switches and some others have lugs.

This is hard to say without testing on an ohmmeter.

Test the wire all the way back to the backbox connector with an ohmmeter.

When there is a question, its best to first check the continuity of the wires and the continuity of the connector to the pin on the pc board.

If you pull out the connector from the pc board slightly, you can test the molex connection to the pin on the pc board to be sure it connects.

An ohmmeter is an invauable tool for checking connections.

for verification, you can touch the wires of a switch directly together breifly in switch edge test.

You should get a beep sound and a display reading of the last switch activated.

This would be the same as the testing in the article above that I posted.

Wear eye protection. Liquid solder splashed into your eye is no joke.

I wear glass lenses in my eyeglasses and a bunch of times a year I have little splashes of solder on my eyeglasses.

Yes, its ok for a test.

Test the wires before soldering them in.

Trace the wires back.

Make sure they go to the right pins on the pc board.

The wires have to be correct.

Check the crimp and connection at the pc board.

Test the wires if you have problems.

If the wires are correct and have continuity, touching them together will be shown in test mode.

We know this is true as you can just jumper the pins on the cpu board and see it in test.

Yes make sure no switches aren’t touching anything but where soldered to. They can be a bitch sometimes to track down and you’re doing right testing now.