Observations from analyzer trace leads to verification of logic on Clock card

 OBSERVATIONS FROM THE LOGIC ANALYZER TRACE

Picking a card starts a timer while circuitry waits for the leading edge of a card to block one or more phototransistors. If the timer counts to zero it triggers a pick check since the card didn't make it into the read station. This should happen when a card does not get pulled into the mechanism. 

In this case, I see the OneDark signal go active when the first edge of the card hits the read station. This should trigger a Good Pick Reset (GPR) signal but that doesn't arrive. With GPR, all the other timing begins, the reader resets the pick timer and signals it is busy. 

Because we don't see the GPR, we don't activate busy nor start into the process of reading this card. Instead, the reader remains Ready without a Busy condition so that the pick is issued again to pull in the next card. We get several cards feeding through in a row before the pick timer counts to zero and triggers our Pick Check. 

The logic to create the GPR from the OneDark requires that a Pick Reset (PCR) be generated as the pick is accepted. I can't see if that occured since the trace starts much later in time after the card has reached the read station. One thing I will verify is the correct issuance of GPR as part of the picking. 

If that occurs, then we are dealing with three flipflops and a handful of inverters and other gates that sit between the poweron reset, PCR and OneDark as inputs and the GPR as an output. I will put the extender on the Clock card to give me access to the chip pins then begin shooting this more fully when I get to the shop. 

Circuitry generating GPR