December 3, 2022

[Sean] from Vintage Arcade Maintenance fixes vintage arcade machines, and he were given a request to fix an excessively particular system. It’s Laptop Area, the primary industrial arcade cupboard ever made, and loosely in line with Spacewar! This grand-daddy of coin-op used to be a literal barn to find, and used to be in beautiful dangerous form after sitting for years. The entire portions gave the look to be unique, making them 50 years outdated. As you’ll be able to believe, that aggregate didn’t bode smartly for the well being of the elements. There’s a pair hours of pictures right here, but it surely’s worthwhile troubleshooting recommendation, and really cool to look such an outdated system being labored on.

Phase one is the intro, and [Sean] began with an HP common sense analyzer, simply probing the various TTL chips at the board on the lookout for floating or another way suspicious outputs. Work out the clearly inaccurate chips and exchange every with a socket and new chip. As regards to each and every diode within the system wanted changing.

Phase two of the restore begins with a damaged hint restore, and the invention that the entire ceramic capacitors at the forums have been leaky. The attention-grabbing factor is {that a} multimeter examined the ones caps as having the right kind capacitance, however a devoted leak tester came upon the issue.

Phase 3 displays the method of operating the remainder chips thru a common sense tester, which discovered extra problematic ICs. In some instances, a chip would simplest once in a while check as operating. And unusually, one of the vital new, substitute chips became out to have an issue. Even though as a commenter identified, it is usually a falling edge vs emerging edge variation of the common sense chips responsible. Or perhaps the brand new chips have been counterfeit. Laborious to nail down.

Phase 4 begins with a gotcha second, the place one of the vital first maintenance to the board used to be a misstep. What gave the look to be a broken hint, used to be in reality a manufacturing facility amendment (a bodge minimize?). Then a fortunate destroy truly helped out, the place simplest part of one of the vital 7476 chips used to be in use, and one of the vital chips readily available used to be simplest part operating. Put the lifeless bit into the unused slot, and the system truly began to act.

Phase 5 is the victory lap, the place the entire elements after all arrived, and the entirety begins operating at the bench. How cool to look the outdated system bleeping and blooping once more.