Digital Games 574 (Knockout) Need Help Identifying Old Motorola TTL IC

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Digital Games 574 (Knockout) Need Help Identifying Old Motorola TTL IC

I've been working on a Digital Games 574 (Knock Out) discrete logic PCB.

https://www.arcade-museum.com/game_detail.php?game_id=12731

There are no schematics or info available and I wanted to document the chips and locations first before doing any more work on the board. I replaced a missing crystal yesterday and got it working but the image wigs out occasionally as seen at the end of the video below.

https://youtu.be/DEX0vcXOCzQ

uynFLZ3l.jpg



5oQYMzjl.jpg



There are a number of chips on the board with 1974 date codes and it adds some confusion when trying to identify some of the ICs.
I've been able to positively identify all but one, it's a Xerox chip number made by Motorola with the following info on the top and nothing stamped on the underside.

M 733W00024
7410

qZuhqOIl.jpg


In the image above the are two 7410s with the date code 7410 above and below the chip in question, when I put the Motorola IC in my IC tester it reads as either 7413/7420/7422/7440. When I put the 7410's in there they read as 7410.

I've had a look through the Motorola TTL databook from 1971 and could find no reference to the part number on top but maybe I'm missing something or it's not a part number.

https://ia800807.us.archive.org/25/...otorola_TTL_Integrated_Circuits_Data_Book.pdf


Any ideas?

P.S. Does anyone happen to have a schematic/manual or other info on these boards.
I have a copy of the 474 manual which was helpful in identifying the crystal frequency 5 MHz but if someone has one of these boards and could confirm that is correct, it would be much appreciated..
 
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Mystery solved.. it's a 7440.

I had a look at the activity on a few of the mystery chips and there was nothing happening at pins 3 and 11.
An inspection of the board revealed they weren't connected to anything which suggests it is in fact a 7440, confirming my suspicion based on only seeing a 7440 or 7420 on the other pong boards and schematics.

HqD9BP2l.jpg


Chip location sheet now complete.


Pa6oCJFl.jpg


I'll add the pinouts and cabinet wiring to the above image and upload it to the Knock Out page on KLOV.
 
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I would build a circuit on a bread board. You can load the inputs to test the outputs to test your theory. It could be possible that the chip in question is bad and is giving you bad results. You could also re-inspect your work and compare the traces and compare to the two chip pinouts.
 
There are four of them on the board and all have no connection on pins 3 & 11.
They are all working as is the PCB that hey are on.
It's definitely a 7440.
 
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