Hi. So I recently did some repair work on my Twilight Zone board (mounting a remote battery). The battery job seems to have worked just fine but, as always seems to be the case, something else is wrong. Specifically, when I press the Start button, it does not start the game. The button is flashing as normal and I can hear the switch clicking, but no game starts. Doing a switch test, the start button does not register (and incidentally, the "Empty Balls" feature doesn't work at all either). Is it possible I fouled something up on the board? A blown fuse? Something plugged in wrong? Any idea where I should start looking to try and narrow it down? Sorry, if this seems a little vague. Just looking for a starting point.

Thanks!

Thank you for the prompt reply LTG! A cursory examination of the wires suggests that is not the issue. I reseated everything to be certain. I am now thinking that the problem is related to the ULN2803A transistor at U20 that I removed from the board during installation (and replaced afterwards). I think it might be giving me errors considering a lot of other things along that line are not responding (saw this mentioned as a culprit in similar threads that I found after making this one. Oops.)

First things first: I have a few new ones ordered and on the way and I'll see if replacing it does the trick. Learning a LOT in a short time here!

Thanks again. I'll update with my progress or lack therof.

UPDATE: I was also getting some Switch Matrix errors in addition to the above (36,37 and 46, 47, which I learned from info on this site is a classic "rectangle" problem). I replaced the U20 chip which fixed some errors (the start button now worked, as did the ball trough and some other areas that hadn't before) but the switch issues were not fixed.

SO, after some further examination, I noticed something new: a little bit of corrosion on top of a few slots of the Molex Connectors for J206/J208. This had been missed by me when I did the corrosion cleaning on the board prior to installing the new remote battery (I just did not think to check/ clean the connectors. Lesson learned, much like the lesson of never leaving batteries on the board...). Seeking to isolate the issue before I ripped anything else out of the board, I cleaned it up and neutralized it as best I could, scrapped off the residue, and plugged them back in.

Success! We're back in business with no errors. I'm gonna give it a little bit and make sure this holds before I mark this solved. And yes, I know I need to replace those Molex Connectors ASAP as well. It feels good to have isolated the problem at least, and I learned a lot in the process.

Thanks again to all of the extremely helpful people here, both in this thread and in the many, many others I searched for the solution to this issue.