So, thanks to this thread: https://pinside.com/pinball/forum/topic/100-sttng-fix-me-challenge-experienced-techs-only, I have gotten to this point. However, I need input/confirmation from the pros here on Pinside that my bridge rectifier(s) are indeed bad.

Quick history: The game has not been used in years. I had grand plans of stripping the playfield and doing a ground-up resto but it just never happened. The only thing that did happen was the installing of a Color DMD. Conceding to my procrastination and laziness, I just decide to get the game playable again. Once I got everything back in (I had removed the playfield) and hooked up, I fired her up. Everything seemed fine except it was continually trying to launch balls.

After diagnosis, I realized row 6 on the switch matrix is out. Of those are the optics for trough #1, under left hole, and under left gun sw. I'm pretty that's why the game was continually launching balls.

After reading through the above thread, I did the test in post #2 from zaza and came up with these numbers:

1= 6.0 mV
2= 13.7 mV
3= 17.8 mV
4= 10.3 mV

I guess they should all read 460 mV? Given that and my weird readings am I to assume my BR is bad?

My game's characteristics were very similar to others that were solved with BR replacements. Also, from other reading, it seems adding a Color DMD can cause power problems on the STTNG.

Am on the right path? Should more tests be made? Thanks in advance for any help.

Chris

Thanks for the reply @pin_guy.

Nothing changed when I wiggled the white/blue wire or when I moved the connector to J208.

I don't see any issues with controlled lamps; they all seem to be functioning in test modes and attract mode - flashers too. The rest of the matrix seems ok too. 12VR = 11.97V and 18V = 17.99V.

One thing I've noticed is the white/blue wire for that line 6 on the matrix seems to be reading at about 11V (on the playfield) and it tends to fluctuate a little. Could there be anything with that. Maybe I have a short somewhere?

Chris

Yes, the entire row 6 is out. Thanks Chris. I'll have to try this tomorrow night and report back as soon as I can.

Ok, was just an idea. I should add, I don't believe there is any corrosion from battery leakage on the CPU board. But I haven't had it off to examine the back. That's probably something I need to check and maybe eliminate.

Thanks guys for the help. I'll report back as soon as I can.

Chris

Well guys, let me first say I apologize for wasting your time. @pin_guy, as I was looking for the test points you mentioned above, I noticed damage on the board from the batteries. This thing sat for some time, and although I though I got the batteries out in time, clearly I did not. I didn't notice it until I got really close tonight.

In addition, I did try the test you mentioned above and no-go. Most assuredly it's due to the battery damage.

Needless to say, I'm pretty mad at myself. I'm not an expert within this hobby by any means, but I know the potential for batteries leaking and reeking havoc and I let it happen anyway.

See the attached picture. I can only imagine what the back looks like, but I'll try and get the board removed tonight.

Depending on how bad it is, is it repairable? I see Rottendog replacements for about $150. I'm tempted to go that route.

Thanks again for your help.

Chris

IMG_1881 (resized).JPG

The back of the board is actually fine. Here's a little closer picture of front with more light.

IMG_6552 (resized).JPG

IMG_6553 (resized).JPG

I've spoken with Rob at Pinball Classics and it probably could be repaired, but possibly at nearly the same or more cost than a new board, so it looks like I'll go the route of a new board.

Chris

Thanks again for all the help with this. New board in and she's playing just like new.

Chris