Hello everybody! I'm working on my SOF pinball machine.. everything it's ok except the jackpot controller lamps in the backbox. From schematica all these lamps se under the strong/column #8 /, driven by the TIP42 #Q52. With the logic probe the signal here must be pulsating, as the others TIPs, but I have only a High-Pulse signal.
The output from the PIA U54 is strong (pulse) so I concentrated my efforts in the TIP42 and 2N6427..
Nothing changed.. same issue.
Changing U52 (7408) same old situation..
So l changed all the involved components (except PIA) but I'm stucked..
Any suggestions?
Thanks in advance
Ciao!!!

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Solved my friends..
Checking again and again and again and again, I found a damaged wire on the connector from cpu to interconnect board.
It was flaking and the connection was not so strong, causing all the above issue.
Also the signal from the TIP42 now is ok!
Thanks for the attention!
Take care of yourself in this quarantine..
Ciao