I have one of these in a Star Trek. It is labeled The Repair Connection Copyright 1996. The LED is only flashing 3 times. All values good off the rectifier board.
Do the LEDs match the Bally sequence? Is there a troubleshooting guide out there for this?
Does anyone else have one of these? If so, how many LED flashes should it have to boot?
40B95AB3-FD1B-4ACB-BE6D-831224CCE910 (resized).jpegE0A57807-5A07-444D-9807-8B35084AFCFD (resized).jpegThe repair connection CPU is the same as the original bally - same software as bally and the software is what's controlling the LED. So no 4th flash is U10 (or whatever that PIA is... it would be the one connected to the switches.)
You can swap the PIAs with each other they are the same. The link posted would be valid to troubleshoot this as well as what's on pinwiki, although chip nomenclature on the board might vary.
Tom C's board was pretty much a direct copy of the original so TheLaw's linked page should apply for this board.
Scroll down to "The MPU Diagnostic LED Flash Sequences Explained". Lack of 4th flash says bad U10.
One thing of note -- the U15 shown in photo is a 74LS37. Although Tom used this IC often, it was not and is still not a good sub for the original MC3459. It's close but not quite up to the task as seen here:
https://www.greatplainselectronics.com/Information.asp?region=138
If you replace any IC's on that board then also replace U15 with an MC3459, 74F37 or 74S37 to reduce marginal signals. Fortunately, that IC is socketed so changing it would be quite easy.
u15 is the most common chip to go bad on the original MPU, besides AMI CPU/PIA/RAM. There is a 150 ohm pullup resistor on one output. I think the 7437 original TTL type with no letters is an OK sub too.... better than the LS flavor for sure.
Double check you are not counting the 'flicker' as a flash. If so no 4th flash means U10 6821 PIA has a problem or the CPU cannot control it properly. I see you have AMI brand PIA chips installed in that board. That brand is notorious for failing seemingly 10x more often than HD6821, EF6821, F6821 or MC6821 brands of PIA. AMI brand RAMs, CPUs, and PIAs are all so unreliable I would not use them. Trash canned so many bad ones it is ridiculous. So consider replacing both U10 and U11, but start with just U10 and see where you are.
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Schertz, TX