Hi guys!
I’ve got a Williams PinBot which hasn’t been used for years due to errors and I’ve been working on it for days. It’s in a not too good shape but getting better. There were broken parts, connections and a few loose cables. One of them was the left lane change switch’s cable and I think it was shorted to the +50 V switch and the switch matrix is partially fried. I went through all the switches and now everything works except the 2nd column. When an item from the 2nd column is activated it is recognized as if it was from the 8th or 7th column as indicated on the picture.

The Q49 2N3904 transistor is definitely damaged( without any visible signs, but resistance between CE is almost zero) but I don’t have a spare one so cannot test if it solves the problem. According to this site http://techniek.flipperwinkel.nl/wms11/index3.htm#switch a bunch of other parts can (should) be fried. Is there a way to find out what should be replaced?
I can get 2n3904, 4011 and 74LS244 but the PIA is not sold here.

thanks,
Adam

switch_matrix_error (resized).jpg

Thank you! I replaced the transistor and now everything is ok