On my NBAFB, Column 9 of my lamp matrix comes on with all the other columns. For instance, if I’m on a single lamp test lighting col 1 row 1, then col 9 row 1 comes on too.
When I unplug J121, and measure voltage between pin 9 and ground, I get steady 18v. I don’t think this is right, it’s much higher than I get for the other pins. How do I troubleshoot what’s wrong in the board? I’m not sure how to read the schematics, would Q97 be the likely culprit?
Also, some of the led bulbs in column 9 are blown and look like they’ve seen more ?voltage? than they should.
Any help appreciated. I’m a novice troubleshooting board problems.
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