Problem: The chase lights on the bride's helmet are not working. They were working, but now they aren't. As far as I know they were working before I took the helmet off to try out a couple LEDs and now they are just off. They don't come on in attract mode, gameplay, or lamp test.

These lights are controlled by a chase light board under the playfield. It takes 13vdc, ground, and two other wires from the driver board. It outputs headers which go to each lamp on the helmet. Separately one wire from the driver board (GI J120-8) is provided as power to the lamps. The chase light board controls the grounds for all the lamps.

The driver board is a Rottendog board. And no fuses are blown.

13VDC exists flowing into the light board. 8VAC flowing out of the GI pin on the driver board, through the connector, all the way to the lamp boards in the helmet. Testing the blobs of solder on the two lamp boards in the helmet (all the ground wires and the one power wire are soldered there) there is 4-4.5VAC which I think is enough to power the bulbs. There is no power at the light sockets.

I disconnected the light boards in the helmet and did a continuity test between the two terminals on each socket all the way to where the associated wires are soldered and I do have continuity so the traces on the light board are working.

Testing power between the live wire and all the individual grounds shows 4.5VAC which I believe means the grounds are not "broken" so the chase lamp board should be putting the lamps in the "on" position...

Re-flowed solder on the light socket boards in the helmet as well as the header pins on the chase light board, neither of which had any effect. The power wire was connected via a 1 pin connector. I cut the connector off and soldered the wires together instead as all the lights being out seemed like a power wire not working situation.

The chase light board schematic: https://farm5.static.flickr.com/4128/4948140073_e74a013dcf_b.jpg

Any ideas at all on what to try next? I've done all the things I could think of/find on the internets.

Yea measured with the meter at the socket and no dice.

It is pulling 12v (meter says 13) at J1. So at least that part is correct.

Helpful, hopefully! It certainly gives me several more things to try, which is better than the 0 ideas I had before. Thanks!

5 volts exist on the 7805 as well as outputs 1 and 2 on the 339. Disconnected connector from chase lamp board and jumper end individual bulb grounds to ground and each bulb lights as I do that. Going to figure out how to test the 74xx chips but since all the lights are out I'm thinking I should figure out where the clock and data pins from J1 come from. Thanks!

Found the issue sorta. The problem is with the Rottendog WPC driver boards. I have two and tried both. For some reason they do not work with the chase lights on the helmet. Switch to the standard WPC driver board and they work like a champ. It's possible it's a problem with the specific Rottendog board version I have (WDB089_2). They say it's compatible with BoP but it is not. Will write them to see if there is a known fix.