NickFolino

It wasn't nearly as bad as older Kenwood audio equipment. Their traces lift and run off when they smell a soldering iron heating up!

She's back up and running! Thanks for the help! It was U26, the RAM chip that was getting hot. I lifted the trace on pin 3 and broke one of the ceramic caps, but they were easy to fix. I'll have to remember to always check RAM on these. I thought for sure it was one of the ROMs just based on symptoms. Thanks again! Nick

They're soldered in. I'll add a socket when I replace them. The ones I'll put in are 150ns.

Interestingly the first chip is different and is a 4164. The rest are MT 4264. I have a ton of 4164 chips. I assume it's safe to use them instead of the 4264. One of them is getting pretty warm, so I'll start with him... Thanks! Nick

So my 130 stopped working. Black screen on power on. I've tried a couple dozen cartridges. But... Pitfall II works fine. The 400/800 diag cart loads, but the jkli keys don't work. ROM test fails, as I think it should. 40k of RAM passes tests. Shamus loads to the start screen and plays a steady tone, but nothing else. Everything else just shows a black screen. To list a few: BASIC, Pilot, Assembler Editor, Robotron, Midnight Magic, Ernie's Magic Shapes, Pole Position, Cloudburst... A bunch of different cartridges from different manufacturers, all black screen. Would this be an OS ROM failure? Could anything else cause this problem? Nick

My 400 date code 402:

I have 2 800's:

Just an update. This Pong is fixed. The 7404 and C12 were replaced. Works like new now.

Thanks, Chas. I have a CRT TV I use for testing old computers. I have the pong apart and looked at it for a few minutes. The linked schematic above is hard to read and appears to have at least one error that I've found. This pong seems to have no clock pulses. I haven't figured out why yet, probably an issue with the chip, which would condemn this guy to the scrap heap :-( Nick

Thanks!

Does anyone have a schematic for a C-100? I just picked one up and it goes from static to a black screen when powered on. Thanks. Nick

Another GTIA chip solved all issues. It's working like new again. Nick

FYI - I did find the service manual. It is a GTIA and it is bad. Adjusting would get any color from it.

So I got a GTIA from ebay. I arrived in a bubble mailer with the chip stuck in a piece of styrofoam. Chip was no good, but it did help me prove that the GTIA was the fault. The new chip worked fine, but had no color. The seller is sending a replacement, hopefully not stuck in styrofoam. Nick

I took it apart and cleaned all of the contacts, removed all socketed chips and cleaned those as well. Same problem. I found this post where a similar problem with the vertical line in Donkey Kong was fixed with a new GTIA. Guess I'll have to source one of those to try a swap. http://blog.tynemouthsoftware.co.uk/2018/11/atari-400-48k-internal-ram-upgrade.html Nick