I have a #WPT and am missing an entire lamp column. I have been banging my head against this for two weeks now and I am almost certain that the problem is the IC. All the inputs match other ICs but the outputs are different. I have replaced the IC 3 times now with the same result. I have traced every path, checked every resistor and diode and all that I can find different is the IC.

I have been ordering my IC's from Marco but now I am wondering if this is actually the right IC. Here is the original IC from the manual (U15):

Screenshot 2021-08-14 111438 (resized).png

and here is the Marco part which comes up with that Stern part number:

0814211108 (resized).jpg

Can any electronics guru out there help me find another replacement for this? I have looked but can't find anything that seems to match.

Well I see, can I ask what you recommend to check it?

Here is the actual circuit diagram:

Screenshot 2021-08-14 101053 (resized).png

So in the machine during "All Lamps" test, I am comparing the inputs (pin 2,4) and getting the same values on U17 (working) and U15 (not working). I am also seeing the same input voltage Pin 3 (~16v) on all of them.

However, output 5 on U15 is a fraction of what it is on all the others. The only other difference I see is that when I measure from pin 1 (ground) to the board ground I see a small voltage on the working ones but nothing on U15. I don't have any idea what this means but it is different.

When the board is out and I test conductivity on all pins (1-5) to their source and got connections. I tested all the resistors and they all test correct. I tested all the diodes and they all test the same as the others.

I can't find anything wrong other than the output of the IC which is why I am questioning it.

For context, when I got this game one lamp column was out. I investigated the playfield and found one lamp socket that had been crushed behind the backboard and very likely shorted. I fixed this. It still didn't work and I replaced the IC but it also didn't work. I then found that the small 47ohm SM resistor on U15 was registering 0ohms. I found a replacement and changed it. Now it measures 47ohm to ground like all the others. However, I note this because that is one variable. I am decent at soldering but it is possible I did something wrong here but if I did I can't detect it. Also the fact that in the live condition the ground pin to board ground measures different makes me question if there is something wrong here.

Additionally, I don't really understand this part but when the board is out of game and I use "diode mode" on my multimeter and check various pins between U17 and U15 they are different.

Anyway, at this point I am not sure what else to check.

Just bumping this up to see if anyone has any advice on how to definitively check to see if this IC is bad or it is just me checking it wrong.

Well not the news I wanted but thanks.

Thanks Chris, that is an excellent idea. I just ordered a desoldering gun and will try it when I get it.

I am also going to check the board again with the IC out. Odds are that it is more likely that I am doing something wrong than I have a bad IC but I can't figure out what.

Also thanks for the link to pinwiki, nice reference. Now I know why it shows switch 1 and 2 in the service menu and they aren't used in the game.

I did that and I get about 25% the voltage on the bad column versus the others so I am pretty sure it is the board.

For context, there was a crushed socket in the back of the game when I got it and I am almost certain it shorted at some point (replaced). When I checked the board previously the 47ohm resistor to ground was dead at 0 ohms (replaced) so I am pretty sure there was damage to the board during the assumed short. The problem is that everything I check now looks good except for the IC output. It makes sense that something else is damaged but I don't know what else to check. When I check the board live the inputs to the "bad" IC match those of the others so it seems like it is getting good inputs but the main output (pin 5) and the ground pin measure different than the others. I keep thinking I screwed up installing the tiny 47ohm resistor to ground but I get connectivity and it reads 47 ohms both ways so I think it is right.

I have changed the IC three times but from the same supplier (Marco) so my thought was that maybe it wasn't actually the right IC for this game (mis-labeled, whatever). That was why I was looking for an alternative supplier but the idea to swap them should resolve that question.

So here is the order of repairs I have done:

1. Found broken lamp socket, replaced
2. IC-15 measured weird, replaced (still not working)
3. Carefully checked the board and found R139 measured 0ohms, carefully changed it but still not working
4. Changed IC-15 again thinking I might have burnt it out with bad R139 but still not working
5. Checked everything on the board again and couldn't find anything but changed IC-15 again and of course still not working

Maybe today I will just start from scratch and measure everything again and make sure I didn't miss something.

If you guys have some advice on what to check I would love that but I will do this:

Out of Game Check:
1. Connectivity of all traces back to source
2. Check resistors
3. Check diodes

In Game Check (during "All Lamp Test" with connector OFF)
1. Voltage into Pin 2
2. Voltage into Pin 4
3. Supply Voltage on Pin 3
4. Voltage Out at Pin 5 and on Connector Pin
5. Voltage across R139 (between Pin 1 and ground)

In Game Check (during "All Lamp Test" with connector ON)
1. Voltage into Pin 2
2. Voltage into Pin 4
3. Supply Voltage on Pin 3
4. Voltage Out at Pin 5 and on Connector Pin
5. Voltage across R139 (between Pin 1 and ground)

Because this is a IC I guess there is no way to check it directly. I can't swap it today until I get my desoldering gun but as you say it seems unlikely 3 ICs are bad.

As always this will likely end up being something simple but it only seems simple after the fact....

Okay so I went through the entire board again and couldn't find anything different other than the IC outputs.

With "All Lamps" everything is flashing and the inputs are all cycling so I am not sure the best way to read live voltage but I did my best and was really looking to see how it compared to the working IC-17. Sometimes I switched to VAC as this seemed to get a clearer reading. I wish there was a way to set a lamp to just be "on" but doesn't seem to be an option in test mode. Here are my notes:

0822211012 (resized).jpg

The differences were:

1. Voltage across 47ohm resistors (Pin 1 to board ground) was something like 0-.3vdc on U17 but almost zero on U15
2. Output voltage was 6-11vac on U17 and .6-1 on U15
3. Output voltage when unplugged was slightly different on U15 .03-.05vac

All connections, resistors, diodes checkout on the bench.

Here is a picture of the board, solder is not perfect but not bad (U15 is the second IC on the far left column):

0822210956_HDR (resized).jpg

I also wanted to make sure I didn't have some weird short across IC pins so here is a view with a bright light behind:

0820211553_HDR (resized).jpg

Am I crazy, doesn't this have to be the IC?

Okay, thanks for the info and confirmation. I probably have an anti-static bag somewhere...

It is worth noting that Marco ships them in a regular bag.

I am also now wondering if the original IC was never actually bad but it was just the 47ohm resistor. I changed them both but still have the old one. The legs are partially cut off but I might try installing it back in. Although if it shorted to ground that probably isn't good for the IC.

I will need to wait for my desoldering gun to try it but I feel like I at least have a direction now. I can't seem to de-solder all five legs with my basic suction tube thingy.

Thanks a lot of the help.

So I desoldered the IC today and removed a good IC. I then took the Marco IC and put it in the spot of the good IC circuit and it didn't work. So I think that is confirmation that this IC is not the right part.

Unfortunately I was hoping that my old IC that I originally removed might still be good (because resistor was actually) bad but after reinstalling it still didn't work so is probably bad.

Am I screwed now? I see I can buy an entirely new board for like $500 but that seems like overkill. Where could I look for someone who has a bunch of old boards and I could steal the IC from that?

It is U-15 on the I/O Power Driver Board, VN02N. Is your turnaround still around 60 days? The game is playable right now and I just got it so I might play it for a few months and then send it in. You wouldn't consider just sending me the IC? It is probably 5 minutes to solder it back in. I am happy to pay but don't really want to wait 2 months.

Chris that would be great, thank you. I don't have an anti-static bag big enough. You suggest to wrap it in aluminum foil. I am guessing just one layer and then into a plastic bag in a padded box?

They should be identical but the new ones aren't working in the board. Here is the manual part number and here is the Marco part.

0814211108 (resized).jpg

Screenshot 2021-08-14 111438 (resized).png

New Marco one on the right and old one on left.

0814211105_HDR (1) (resized).jpg

Thanks a bunch, Chris.

Yeah it is good to know I wasn't just doing something dumb but it sucks if someone needs a new one of these because I believe Marco is the only supplier. Marco is aware of the issue and has been very responsive. I need to send them the exact lot numbers of the ICs I got and I think they will pull them but I don't know if they have any more.