Hello! I’ve had my BK for almost 2 years now and have a problem that popped up. When first getting a multiball the lights flash on and off, including all the back box and all other background lighting. Recently instead of flashing the background lights would stay off until after the multiball session was over. Then they stayed off a little longer than the multiball session, then stayed off all the time which is where I am now. All other lights work, just the background lighting stays off. Tried resetting the power and checked fuses to no avail. Then started looking into the boards and schematics and then remembered the previous owner installed a Main/Driver combo board which is the Rottendog MPU327-1. Did some digging on pinside and realized this board has issues with the BK and is no longer supported for the System 7. So, now I realize I may have a bigger problem than a bad component. It seems the preferred MPU/Driver is the Kohout Enterprises System 3-7 Replacement board which runs $425 when it becomes avail again. I prefer to not drop that kind of $$, but if it’ll solve this and other future headaches, it may be worth it. So, I’d like to ask some advice; do I keep troubleshooting the no longer supported Rottendog, do I wait for the Kohout and hurt the wallet, or are there any other options?
Finally, the way it was acting tells me it’s either a software issue or possibly a bad component on the board. I do not think it’s a wiring issue, although I’ll probably check that just to be sure.
I appreciate any ideas, suggestions, etc in advance. Thanks!

Unfortunately, no. The gent I bought the BK from installed the Rottendog and I believe sold the original.

Thanks Mike. I’ve been unable to find out what the Rottendog compatibility issues are and assumed the lighting may be one of them. I looked everywhere for a relay and the only two I see are K1 on the MPU/Driver board and K1 on the power supply (also Rottendog).
When I’m talking about background lighting, I mean both general white ground illumination and upper back panel lighting. On the back panel I still get “high score, match, shoot again, etc” lit up as well as each of the 4 score displays, but the rest of the background or general lighting is out. I assume it’s either a timing circuit or a relay, but again without knowing the Rottendog compatibility issues, I didn’t know if it would be worth my time to troubleshoot this particular issue.

Thanks @racingpin! I looked for the relay and found nothing. This led me to look at the schematics and between the original drawings showing how everything flows and picking that up on the Rdog drawings, led me to see the K1 relay on the power supply is the one controlling the general lighting. I then looked at connectors CN7, J86, and CN8X9 on the Rdog PS and low and behold I found J86 to be nice and toasty as you can see in the pic (back side is overdone as well). I can’t even disconnect it because the connector is welded together. Now, per the Rdog drawing it looks like I should be able to connect the yellow wires coming from the main transformer 17&19 to the Rdog PS connector CN9X4 pins 2&3 after I get the proper connector. Now, in the OG PS, there was a 20A fuse in line with this circuit, but the Rdog does not have this particular circuit protection in its PS. I wonder why that is? So, if anyone reading this can confirm I could move the two main transformer wires to CN9X4, I would very much appreciate it!

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That makes sense. I’ve been trying to find the correct replacement Molex connector, but I’ve been unsuccessful. Any idea what the correct part number is for this thru hole connector? Attached is a pic of a un-toasted Rdog PS J86 connection.

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