Hi guys! Another trouble for me
In the second 8x4 lamp matrix, the row 11 is completely out. I've checked diagrams and analysed the signal... it runs from PIA 6821 (IC5) to pin 11 of 7406 (IC1), then it is inverted and continues its path trough resistors and diodes.
At the exit of pin 10 the signal is different if compared to the others of the matrix (f.e. pin 8 or 12 of IC1).
The others signal are pulsating low, while for row 11 is pulsating high-low. Thinking the problem was IC1, I changed it but the problem remains.
Any suggestion?
Thanks a lot!
Grazie e ciao!!!

IMG_20170727_232616 (resized).jpg

IMG_20170727_232644 (resized).jpg

Anything is possible!
At the moment I checked continuity between driver connector and lamp socket. I also check the lamp socket diodes and are fine.
Why the signal in exit of pin 10 is completely different, is "dirt"...

I will try when I come back from work.
From schematics is a NPN darlington transistor, but without specifications. From the Williams Number part (5162-09410-00) is a simple TIP 102.
But on the other unofficial diagrams on ipdb (as showed in my picture), is a 2N6427... strange thing!

Finally I found the culprits: IC5 (PIA6821) and IC4 (7408)... once replaced, the lamp problem has disappeared.
I had another troubles with solenoids (7 of 8 TIP102 burnt), solved changing them with new ones and also changing IC3 & IC7 for wrong blanking signal on the output.