Hey guys, So I'm still working on my WCS94 restore and finally got to the main problem I knew of when I bought it (after tackling all the other problems that came up once a closer look was done).

But I knew the game had a bad U20 chip (which luckily for me is socketed, just need to wait for new chips to be shipped) - I had all plugs removed from CPU board and still got ground short error. I'm getting the ground short error on boot and then cannot use the diagnostic buttons, after reading a bunch of stuff it seems to be a bad U20 and maybe a U14. However, if I go into diagnostics (I can get the coin door buttons to work if I flip the #3 toggle switch to off or on (cant remember the name of it, but its the 8 position toggle on the WPC-S board and it does a factory reset)), and go to the all lamps + flashers test, the lights will go on but both flippers will also stroke and then I will loose ability to navigate through the menu by way of the coin-door buttons and have to power off the game.

Basically, I am just lost at this point as to what is wrong. Has the ground short error, but the inserts and illumination Also seem dim (especially when compared to brightness they give off when I go though single lamp diagnostics in the menu). Couple that with the flippers going off in the all illumination + flashers action.

Hopefully something in that makes sense (typing out in an iPhone), would those possibly be an issue with the power being delivered? Wall power is good, but haven't tested board voltages yet...

Thanks guys!

Sorry for the long winded/random explanation above (I hate typing on an iphone). But I'm just curious if the issues are related or if they are separate issues.

I figured that it has to be a board issue since it still gives the ground short error even with all plugs pulled from the CPU board (which I'll hopefully have the replacement U20 chip by the end of the week). But the fact that the GI/inserts are dim makes me wonder if the power is also lacking - example, if I boot up the game and let it go into attract mode the frosted LED's for the ramp billboards don't even light up during the lightshow sequence; but if I go into test mode and cycle through each bulb, the individual LED's are bright and look how they should look on a functioning game.

So for the GI and insert issue, should I start with checking all test points on the board for voltage levels? Hopefully my thread isn't coming off as too much of a chit-show with the multitude of problems I just don't know where the best place would be to start with these two (probably not related) issues.

Pulled the chip, and without it in there I am still getting the ground short error row 1 (also had pulled fuses 114 and 115 to check and they are fine (reinstalled prior to testing without the U20)).

^Awesome, thanks PBM! Will check once I get a chance and report what's up. I will likely test all points, but it is TP8 for the GI, right (should be 18V?)? Still can't think of anything that would cause all of the inserts to be dim when the game is in attract mode, but when each bulb is tested individually they light up bright.

Thanks Chris (I always forget about pinwiki)! And after reading through, the problem with the inserts being dim could also be a burnt connector.

Okay, so I went through and recorded all the voltages with the game in attract mode and here is what I came out with:

TP1: 14.75v
TP2: 5.17v
TP3: 5v
TP4: 0.4v
TP6: 77v
TP7: 23V
TP8: 8V

I quit focusing on the U20 chip after I thought about all the other problems the game was having outside of the ground row error it was reporting. And after seeing the TP8 voltage I could tell why my inserts were very dim, so I decided to swap out the power driver board with the one in my TZ (which I knew worked), fired it up and sure as chit the game plays without error.

So, would my likely repair be to replace BR1 and BR2, along with the C6/C7 (and probably C5/C11 as long as I'm at it)? J101 and F114/F115 all look good.

^Will do and thanks for the heads up. Hopefully the Hakko 808 will work it's magic like it did for all the clapped out transistors/resistors I already replaced on that board

Totally understand and definitely no offense taken. I will definitely replace BR1, C6/C7; once those are replaced I'll likely add back into the game to see if that fixed the problem (if not, diagnose from there).

But very much appreciate all the help and reassurance as to my assumptions of the main problem.

Finally got around to working on the board. Replaced the C6, C7, and BR1 and everything now works as it should on the original board!

Hopefully this will help someone else on the forum - I was getting the ground row 1 short error and originally thought it was a U20 chip that had crapped out; but with my GI being very dim in attract mode I started testing the voltages on the board I realized the main culprit was actually a bad C6/C7 and BR1 for my +18v.

Thanks so much for everyone's help on this!