I have a BK2000 that has a light matrix issue. The first 4 columns light exactly how they should in single light test. When I get to the second half of the matrix, all 4 lights in the corresponding columns light up when I test a single light. So for the entire second half of the light test, there will be 4 lights on for each lamp. The lights flash just like they should. Nothing is locked on, just 4 lights flashing for each second half of the light test.

I have even disconnected the connectors for the strobe and return off the cpu board and checked the transistors withe a logic probe. The transistors are not functioning like the first 4 with all wires disconnecting. It is acting like something in the cpu board is telling it to act differently.

What I have changed - all new tip 42 transistors, new pre driver transistors, new 7408 chip for the second half of the matrix, and a new 6821 PIA.

Little bit of an update, I swapped out the CPU from my Whirlwind in to BK2000 to verify my issue is on the CPU board. Game works perfectly with that board. So I don't know where to go from there. All of the components that seem to control the second half of the light matrix have been changed out. My logic probe is still showing that those 4 transistors are firing together when only one should be on during the specific light test. Any insight is appreciated.

Thanks

The corresponding lights on the same row of the matrix light up at the same time the single light is supposed to. So for the entire 4 columns there are 4 lights flashing during single lamp test.

It was a 74LS08 that I used for a replacement. I agree it points to a column driving issue, just don't know where to go from here. I could replace it again with a new one, but there was no change after replacing it the first time. Making me think that there was nothing wrong with the first one.

It is a board issue, sorry If I wasn't clear on it. The board from Whirlwind works perfectly in BK2000. Lights test just like they are supposed to.

I would agree as well, that was the first thing I replaced since it had all of the columns connected to it. Unfortunately that didn't change anything.

Gotcha! Thanks

I believe the returns are controlled by the 7408 and the rows are driven by the 7406. That is just what I am seeing on the print, maybe I am missing something.