Thanks for the write-up Walamab.
It's been 44 days since the last new board update. I have revised a couple of the boards but didn't think it was worth spending much time on documenting it. I got a batch of test / prototype boards in today and was hoping that I have finally nailed what I was working on - at least the primary focus. I built a board and went to test it and it (FINALLY) worked.
The short of the story is that I made a few test boards trying to implement this feature but two revisions failed. I'm a DumbAss and couldn't figure it out so I had to go back to basics and created a set of boards to assist in the testing and developing of the features. I'm still a DumbAss as those basic boards had an error in them <sigh>. I overcame those and as I just mentioned it finally works.
So what is it? It's an opto board design. Improved and re-designed. No more LM339s. Just super cheap ($0.02) 2N3904 transistors. As a bonus it includes diagnostic LEDs to show that the transmitter/receiver pair is working independently of the switch matrix circuitry. For the pièce de résistance (just kidding) it includes a cheap switching regulator to reduce the voltage from +12V to +5V to reduce the power consumption (and therefore heat generated) by the current limiting transmitter resistors. I have the +12V (basic) design working. I last tested the +5V design but want to double check it as the next step.
As part of all this I also have a system of diagnostic boards for the 3-opto, 7-opto, 10-opto and 16-opto boards that allows the diagnostic aspect of the re-designed boards to be used with original Williams boards. This allows diagnosis of potential transmitter/receiver problems versus the LM339 circuitry on those boards. This system of boards is only partially implemented and built. The prototype board just passed today. I will post a follow up with the support boards when I get a picture of them. Expect that in the next few days.
This is the set of boards that I had made to go back to the basics. You can see the patch I needed to test due to the incorrect basic design. Yes ... I am a DumbAss. These boards allowed me to get things working properly though.
This is the latest (final) revision of the "integrated" test board (for +12V). It works in an actual machine - I tested it this afternoon. I need to move this electrical design adhering to the physical restrictions of the original Williams boards.
This is an image of the working LED diagnostic board for use with original Williams boards. Lots of wires and connectors that will be somewhat simplified in the final system. The final system has "plug-in" boards that mount onto the original board and then use RJ-45 (Cat5) cables to transmit the power and signals to the actual diagnostic board. The reason for this is that the cables can be of any length and run out the coin door so that the optos can be tested when the playfield is in the normal position in the machine (not raised).
I am also working on a single (not master/slave) System 11 alphanumeric display for all double alphanumeric panels. It should support all System 11B/C and Data East. Yes ... these already exist but as with most things I just want to make my own for the sake of making my own.