There are two switches at the coin door.

1. The switch matrix switch for "Coin Door Closed". This is a SPDT switch that probably has one spade connector cut off. This would be the NC terminal. This is switch 22. There should be two female quick connectors. One GRN-RED. The other WHT-RED. You can call this the "memory protect" switch but it's a switch matrix switch rather than any direct switch so it's unlikely that it actually hardware protects the memory. If it does this then that function is in the ASIC. The software does not allow you to enter diagnostics if the coin door switch is closed. You can disconnect the two quick connectors and this should open the switch. If that still doesn't work then look carefully at the CPU board for potential alkaline damage to the switch matrix circuitry.
2. The high power interlock switch. This is a DPDT switch that should have two spade connectors cut off. These would be the NC terminals. This interrupts the transformer secondary for the high voltage to the power driver board. There should be four female quick connectors. Two are BLK-YEL. Two are WHT-RED. You can bridge these two connectors to bypass the switch. Some machines also have a "tap" connection that routes wires from the transformer to the coin door interlock switch. You can remove this "tap" connection and also bypass the interlock switch.

If you have +20V at J106 and J107 then the interlock switch is NOT interrupting the high voltage. Check for voltage at the actual flasher bulb sockets. If none of the flashers work then you probably have an interruption somewhere in the wiring. If you're concerned post images of the connectors at J106 and J107. Also post images of the CPU board if you're concerned about that. Descriptions are great but seeing an image is much better.

Focus on getting this working first. You can rule out the physical switches by testing the functionality with the multimeter. It is probably easier to test functionality directly at the board by shorting the pins on J205. See https://www.pinwiki.com/wiki/index.php/Williams_WPC#Direct_Switch_Problems for more information.

The images you posted show no obvious problem. That's visual inspection. To be sure electronic inspection (multimeter) is required. Focus on the direct switch problem first. This will allow you to get into diagnostics to further test the flasher problem. When you do get into the flasher test see if the flashers in the backbox insert work. These are powered from J106 whereas the playfield flashers are powered from J107.

flasher_power.jpg

Red vertical lines go to the coin door interlock switch.

If you have +20V at J106 and J107 then the interlock switch is NOT interrupting the high voltage.

This is normal functional (expected) behavior with the coin door CLOSED.

Test point = GOOD.
J107 = BAD.

Problem is on your power driver board (PDB).

flasher_power.jpg

Green = GOOD. Red = BAD. Orange = connections. Magenta = possible bad component.

1. Take the board out of the machine.
2. Post an overall image of the front and back of the board.
3. Post more images (front and back) focused on the upper right quadrant of the board.

Make sure your images are in-focus and well illuminated so things can be seen.

Suspect the big "sand" resistor is open (infinite resistance). Measure continuity (or resistance) across it. It is a 0.12 (R12) Ohm so your multimeter may not be able to give an accurate reading. Essentially you're looking for continuity or open.

Hmmm. You're right. Fortunately I haven't had to mess with that part of a power driver board. In this case then it should be a problem with the traces. There aren't a lot of places where the trace goes. It goes up from the resistor/TP to multiple VIAs to the J107-6.

OP: Check continuity from the TP to J107-6. It has to be broken if you have +20V at the TP but 0V at J107-6.

With the information that you have provided, you have reached the limit of my ability to help you. What you have described does not make any sense and I cannot make any further suggestions to help you in this remote capacity.

• +20VDC at the test point
• 0V at J107-6 despite continuity through simple traces and VIA between the two points.
• Continuity between the wire at J107-6 and all connections to all bulbs (sockets or headers) in the playfield.

Given the above I think you will need someone else local to you (present at the machine) or you will need to provide many more images (doesn't seem practical as images don't always show electrical problems).

Someone else may be able to provide more assistance but as I just mentioned above ... with the information you have provided you have reached the limit of my ability to help you.

I had thought yesterday that perhaps you were not measuring correctly but I always assume people know what they are doing when they report measurements. I assume people will ask for help on how to measure if they are unsure. This is the least insulting way to proceed. If you don't know how to measure correctly then ask for help on how to do this. One useful tip to verify you are measuring correctly is to measure the other test points to see you are getting consistent and correct results for them. If none measure as expected then you are probably measuring incorrectly.

When the coin door is OPEN the high voltage AC source (20VDC and 50VDC) is interrupted. This means that you should measure 0VDC (or near 0VDC) at the test points. If you get correct voltage measurements with the coin door open then the coin door interlock switch is either wired incorrectly (unlikely as this would interrupt high voltage when the coin door is closed) or the coin door interlock switch has been bypassed (disabled). This information was stated above in post #6 (https://pinside.com/pinball/forum/topic/need-a-little-help-troubleshooting-a-problem-with-my-wcs-94#post-6992953)

Solenoids in Williams machines are individually controlled by a drive transistor. Each one has its own drive transistor. There may be multiple flashers (wired in parallel) controlled by a single drive transistor. It is extremely unlikely that all drive transistors fail at once to stop all of them from functioning. It is more likely you have a power problem. A power problem could be voltage source or daisy chained power distribution wiring.

In the meantime you can test the voltage coming off the transformer secondary for the high voltage AC source. If the PDB comes back from your repair technician correctly repaired then having a verified transformer secondary output means you can eliminate the voltage source and focus on the power distribution.