Support Ed @ GPE.

https://www.greatplainselectronics.com/proddetail.asp?prod=6264LP-70
https://www.greatplainselectronics.com/proddetail.asp?prod=6264LP-55

Otherwise ... search for "AS6C6264-55PCN" on your favorite electronics merchant website.

I think either will work. I don't know what the actual timing requirements are in terms of nanoseconds. I think the original ICs are rated at 100ns so either 70ns or 55ns is faster and compatible. I have used the AS6C6264-55PCN which is a 55ns part.

I don't know what you are calling the Main board. There is a MPU and power driver board.

With power off, press on all socketed parts (U9, game ROM and CPU chip) on the MPU board. This is potentially a problem.

If it still fails, measure the voltage C31 on the MPU board, with power on. What is the voltage? If 5v is lower than 4.9v, then reseat J101, J114 and J210, as these are usually the source of low voltage that cause a WPC game to reset.

This is supposed to be 5volts. What were you using as ground when you were testing the voltages at the DMD? Best to wedge the one meter lead under the ground braid wire in the bottom of the backbox so you don't have to hold both leads.

I don't see how you came up with 7volts on the 5volt rail. That is why I was asking where you were using ground from. Ground braid I see is what you did do, that's great.

C(capacitor)31 on the MPU board. Still using the ground braid for ground, use your red meter lead and touch the C31 on (+) side, which you will see labeled on the MPU board. What does the voltage measure? Just wanted to be sure you see the same voltage on the MPU as you do going to the DMD or not.

Very unusual. Best to unhook J114 so it no longer sends too much voltage to the other boards until this is fixed.

Can you post a picture of the driver board? Also can you test the 5volt test point that is near J114 after disconnecting it?

Just my opinion here. I do not think that driver board repair kit you plan on purchasing will help. The kit is made to repair low voltage, but in this case, the 5volts is measuring too high. Even with that, there is a good chance to damage the board as what comes in the kit. The parts are quite difficult to remove without damaging the board.

So this is a very good step in measuring voltages to really determine where an issue may be coming from.

Ok. Thanks! That is still measuring too high. I can tell C5 was changed, and that happens to be in the 5volt circuit. So with that, likely the BR2 was changed, even though I can't really tell from the top view.

I ask now that you remove the driver board and take a picture of the backside of the board. I suspect that someone jumpered something wrong, most likely because of damage to the board after replacing C5/BR2, causing the 5volts to be too high.

No rush here. But before you remove the board, I had another thought.

Does the serial number label (back of the game or on the right inside of the cabinet just above the power switch) show this as a 120v or 220v game? If it is 220, then you'll have to change jumpers on the input of the transformer most likely. Some of the voltages you measured that are shown on the OP are starting to lead me to this.

But if it is 120v, most likely what I stated in post #19 will likely be the correct path.

Ok. It is quite strange to see some higher than normal voltages, not just the 5volts.

Next, need to see how the input is wired up to the transformer. Just follow that black and white wire from that power distribution box to the 9 pin connector going toward the front of the transformer.

https://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Early_WPC_Transformers_.289_pin_connection.29

The first picture is what we are wanting it to be.
pasted_image (resized).png

I think it is wired up for 220v, which likely is like this.
pasted_image (resized).png

I'm in no hurry since I should be at work tomorrow. That is assuming this new hurricane doesn't slam Houston this time. They sky has gotten a bit quite the past hour, but that may not be the end of it.

Good. You'll need a break from storms the rest of the year.

If the transformer primary jumper settings are set to 230V (Europe) then the transformer secondary should output a voltage that is 1/2 the desired voltage - i.e. it should be too low. Almost certainly too low for the digital logic to operate correctly.

I think more likely someone perhaps set it to low line 105V (Japan) and that when you shoot 110V through the primary it will output a slightly higher voltage based on the ratio of 105:115 (actual output depends on the line voltage in your house).

However ... the LM323 is *SUPPOSED* to regulate the voltage to +5V REGARDLESS of the rectified input voltage level.

You can also check for AC ripple output from the bridge rectifiers as that may give the regulator a little of grief.

Thank you for jumping back in. So if it is set for 105v, what do you expect the jumpers to be set as since it is not on Pinwiki?

If the transformer is not wired correctly for 115 volts, then there would not be a need to remove the driver board at this time.

Also, the fuse in the power distribution box that is labeled 220v also has another label that states 4 amp. This fuse needs to change to 8 amp slo blo when set for 115 volts. So can you look to see if 8 amp fuse is currently in that fuse holder?

Lets see a pic of the power selection plug.
Other possibility is that the back of the board has the resistor hack done to raise the 5V.
BTW... You are in great hands with the help DA and PM have given you.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The new place for pinball repair info

The schematic describes the configurations.

transformer_low_line_voltage.jpg

When looking at your 115V configuration take the wires in pins 7, 8 and 9 and move them to 4, 5 and 6. That's the low line voltage selection.

This is good advice. It's for correctness. It's fine to under fuse the main line fuse so it isn't 100% necessary but always good to restore the machine to the correct factory configuration. I do this on all re-import machines.

100% agree with this. A picture is worth 1,000 words. I would like more people to post more pictures when they ask for help but alas that doesn't seem to happen too often.

I have done this hack (for someone who requested I do it to their board). It didn't raise the voltage to the > +6V range. It only raised it to about +5.1V.

Well, this is odd. It definitely started to sound like the input was wired different than 115v.

Looks like we will probably will need the picture of the back of the power driver board.

Hard to imagine having a failed transformer in this case. Can I bug you for a picture of the transformer?

Any chance your meter has low battery indicator on? That can cause some strange measurements at times.

Yes, please. I think you only need to plug in J101 and J102 on the right side to measure all the voltages on the board as you did in the 1st post.

Oh, I forgot the top left J112 does bring in the other 12V for optos and motors. Can you go ahead and connect in everything on the top of the driver board. Actually, you probably could go with all but J114.

TP2 is now 5.02v which is more like it.
What are TP1 and TP8?