Atari Battlezone arcade (1980) repair, part 4

I bought a 1980 Atari Battlezone arcade from Craigslist, "complete but not working". I finally get it working after having it sit around unfinished for the past year and a half. The reason for it not working surprised me.
This game was the third of the first three vector graphics games released by Atari, the first two being Lunar Lander (1979) and Asteroids (1979). I apparently chose the least popular of them all :)

[@The_Zed_Word]

Thanks for this video series! The Battlezone i picked up last summer had almost all of these exact issues, along with more. I wouldn't have been able to fix it without your videos.

[@nickf3242]

Awww man, automatic like! I was waiting for this!

[@mohamedMagdy-pp2wk]

So I understood everything except the game 😂 Thanks our lovely old board fixer ❤️😂

[@DaveMcAnulty]

Tank spotted at 26:18, goes from center of screen to left.

[@troyer777]

Great to see progress on this! Hopefully you just need to adjust the brightness. Have you gone through the self-test? That will display a cross-hatch pattern to help you adjust the monitor, and will report any problems found regarding bad ROMs, PROMs, or RAMs, etc. Should be a switch in the coin door to enable it.

[@RobertBaruch]

Yes, I did that originally but I neglected to do it again. I'm pretty sure there are supposed to be mountains in the background, but I didn't see them. And the tanks were still quite dim.

[@troyer777]

@@RobertBaruch There definitely should be mountains, and the enemy tanks are not equipped with any stealth technology. I'm sure you'll get it eventually. I've never owned a Battlezone - wish I had more ideas to share. I used to collect arcade PCBs to troubleshoot. Started when we both worked for NYNEX in White Plains. I'm motivated to get my Asteroids Deluxe back in working condition after watching this series. Best of luck, and I hope to see a part 5!

[@cfella1974]

It’s great to see you back working on this again! You’ve got yourself a great collectible machine there... These old Atari PCBs generally require a little maintenance to keep them working reliable. I’d recommend removing those roms and cleaning the legs with Tarn-X. Flaky sockets are also common on Atari boards. Use dual wipes if your up to replacing them. With the roms out you can verify them with your tl866. Google romident (arcaderestoration.com). Also look your interconnect header pins over close for bad solder joints. Suck all that old solder out completely with your Hakko and reflow them all if you find any suspects. I agree with Thomas Royer that you should check your contrast / brightness on your vector monitor and pull up that test screen to verify no errors such as mathbox etc.. Great Job Rob - I really enjoyed watching these vids!

[@RobertBaruch]

Yep, it was just the contrast control. When adjusted, it looked great, and everything showed up.

[@allaynawilson4793]

that sure is a futuristic looking server

[@AmauryJacquot]

J9 was the one above that... H...I...J...

[@darrenolafson5266]

Nice repair. There is an open source command line application for the TL866. gitlab.com/DavidGriffith/minipro/

[@waynegram8907]

What is the Atari Battlezone arcade game using the LS399 chip has 4 bits multiplexer and 4 bit register to do what? What do you mean by you're "strobing" the clock signal? I'm not sure why they are calling it a WORD to select 4 bits because a WORD is 16 bits

[@RobertBaruch]

According to the schematic, it looks like the chip selects either Z data or Y data to display for a particular amount of time. I'm not really sure what logic is used to select Z or Y. "Strobing" means setting the signal from low to high and then back to low (or from high to low and then back to high). And finally, a word is as big as the machine defines it to be, usually the size of a register. For this chip, a "word" is 4 bits.

[@waynegram8907]

Thanks for the help, What is the Magnitude Comparator IC chip being used for in Atari Battlezone arcade game?I had no idea strobing means low to high and then back to low or high to low and back to high, Why would you want to do Strobing to a clock signal? mostly a clock signal is constant active toggle, I'm confused why would you want to do strobing

[@TomStorey96]

@@waynegram8907 strobing is just a single clock pulse if you will, on an infrequent basis, perhaps driven by software or some other part of the circuit when presented with the right combination of signals. You might do it to latch in some data that is waiting at the inputs so that it can be presented at the outputs, or stored for later, e.g. to read buttons or update some outputs to drive lamps or relays or provide inputs to other parts of the circuit etc. You would have to examine the schematic to understand why a chip is there. A magnitude comparator usually compares to sets of inputs, perhaps numbers, to determine if they are of equal value, or greater/less than. Why you would use one depends on what you are trying to achieve.