cerror Posted May 5, 2017 Share Posted May 5, 2017 (edited) Hello! I have this really weird problem with my Atari 800xl. After just finished building in, and testing my stereo upgrade next to my u1mb, I did something stupid. Well, I saw my mistake after the first black screen but I can't for the life of my understand why the problem persists. So, what happened? Well this: for the stereo upgrade you need to add a wire for the pin 15 on the GTIA chip and pin 13 on the cpu, Did that, tested it opened up, worked so yippeee right? I wasn't thinking 100% straight and put the shielding on, screwed the atari together and turned it on. Black screen. Fuck!!! I forgot to tape off the exposed wire @ the gtia and cpu and so they probably came in contact with the shielding and you can guess the rest... So now I get a black screen, and after a couple of seconds a low sound starts, and ramps up in tone in around 7 seconds and then ramps down again... It's not ramping up in volume, but ramping up in frequency. So it starts at C#1 or something and ends up at C#4, but not all the way up. Does anybody have an idea whats goin on? I tried disconnecting the stereoboard and just seat the pokey but no cigar. Maybe a fried CPU or GTIA? I am not a hardware specialist but this wasn't my proudest moment... :'( Edited May 5, 2017 by cerror Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted May 5, 2017 Share Posted May 5, 2017 (edited) What stereo upgrade are you using that requires S3? They all use A4 (your CPU wire), but I can't remember one that uses S3 (your GTIA wire). Edit: I'd look at the CPU, and then ANTIC before suspecting GTIA. Edited May 5, 2017 by Kyle22 Quote Link to comment Share on other sites More sharing options...
Rybags Posted May 6, 2017 Share Posted May 6, 2017 S3 is the keyclick line, likely tapped so it can be mixed on the right audio side. A black screen that doesn't roll would indicate the GTIA is probably OK. If you do multiple powerups (leave about 15 seconds between them) where every time it goes to a black screen, but doesn't stay brown/red or have stripes (stray PMs) then that indicates the CPU and OS are at least OK to the point of initiating the system. A ramping tone is weird. Pokey can't do that on it's own. Maybe take a video of this thing. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted May 6, 2017 Share Posted May 6, 2017 (edited) what support chips share those lines? a picture is needed to make sure there is no confusion as to what lines were actually wired up here... Edited May 6, 2017 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted May 6, 2017 Share Posted May 6, 2017 The keyclick (on XL/XE) is already mixed with the left (original) channel. This must be only to have the GTIA sound active on both sides. Shorting A4 would most likely cause the Self-Test to pop up about RAM failure, and anything is possible if A4 is held low. Part of the sound test could be activated. Were any of the tones the same as the Self-Test? Quote Link to comment Share on other sites More sharing options...
Rybags Posted May 6, 2017 Share Posted May 6, 2017 (edited) If A4 was held in a particular state, the OS would barely get a chance to execute the first dozen instructions. I'm guessing here something's probably fried to the point of still barely working. The thing with the address bus is that it's shared with almost everything - inbuilt Ram has some isolation since there's multiplexing for Ras/Cas, but Roms and IO space have direct connections to some of the lines. Ultimate 1 Meg uses an SRam, not sure if there's voltage conversion or anything going on there but chances are it has direct connection to the buses and it's onboard ICs. It might be worthwhile if you still have your original OS and MMU to see if you can get back to a stock config... years since I did my Ultimate 1 Meg but I think you should be able to do so without undoing the mods required to run it. Edited May 6, 2017 by Rybags Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 (edited) I've used this manual: http://lotharek.pl/zasoby/produkty/45/pliki/simple_stereo.pdf And I double checked the pin connections, I got the right ones. I will make a video of the ramping today and some pictures of the board (hint: wire mess) Edited May 6, 2017 by cerror Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 Here is a video, mainly listen. https://youtu.be/kZm5R86xkMg I tried taking out the stereo board and just putting the pokey in, but same result. As you can see it also has a U1mb and I reflashed the rom and that also didnt work. Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 I tried a spare GTIA and the problem persists. So I am going to try a spare CPU. Downside: because of the U1MB, I need to solder 4 wires to it. :'( Quote Link to comment Share on other sites More sharing options...
Rybags Posted May 6, 2017 Share Posted May 6, 2017 It doesn't sound like Pokey... maybe it's somehow being generated elsewhere. Rather than solder up another CPU, why not just try the other CPU with the original MMU and OS in place instead of the U1Meg. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted May 6, 2017 Share Posted May 6, 2017 The keyclick (on XL/XE) is already mixed with the left (original) channel. This must be only to have the GTIA sound active on both sides. Remember that the entire audio circuit between Pokey and the jack is bypassed by the stereo board, so GTIA audio needs picking off and mixing on-board. 2 Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 (edited) It's not the CPU or the GTIA. I have tested them in another 800xl board and it works. So it's gotta be something else. Maybe the U1MB or even the Pokey(s)? EDIT: Also not the Pokey. Edited May 6, 2017 by cerror 1 Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 (edited) None of the bottom chips are the culprit. Gotta be something else. Edited May 6, 2017 by cerror Quote Link to comment Share on other sites More sharing options...
Rybags Posted May 6, 2017 Share Posted May 6, 2017 OK... didn't realise you'd verified the CPU and GTIA as good. But that's still good case for testing without the U1Meg. Not 100% here but I think you can powerup without a Pokey to blue-screen... I suspect the disk boot attempt would probably have to timeout on every attempt so might take a real long time. I had a Pokey where I'd inadvertantly stopped the IRQ line from conducting but still got a normal looking powerup. Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 (edited) I dismounted the U1MB and got an mmu and rom from a 600xl and the 800xl works. So it is the U1MB. Fuck. Edited May 6, 2017 by cerror Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 Fuckin hell. I reseated the rom in the U1MB, took out and put in the battery, mounted the U1MB in again and now it works! I need to do the rest (stereo) and test it more thorough but it seems like that fixed it! 2 Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted May 6, 2017 Share Posted May 6, 2017 Fuckin hell. I reseated the rom in the U1MB, took out and put in the battery, mounted the U1MB in again and now it works! I need to do the rest (stereo) and test it more thorough but it seems like that fixed it! Did you replace the battery? Or at least check it with a multimeter to make sure it's not failing (voltage tends to drop off as they die)? Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 Did you replace the battery? Or at least check it with a multimeter to make sure it's not failing (voltage tends to drop off as they die)? It's a pretty new U1MB, but I think somethings up because it won't save the config in the menu... Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted May 6, 2017 Share Posted May 6, 2017 It's a pretty new U1MB, but I think somethings up because it won't save the config in the menu... Okay, others have reported *THIS* kind of problem a few times - personally I had my U1MB in a 1200XL and experienced this same thing (settings not saving, and also occasionally scrambled character display in the menus). Super-geniuses Mathias (hias) and Jon (flashjazzcat) identified the cause of the issue as "noisy" Reset lines in some Atari boards. Some people can fix it by replacing a key 74xx logic chip on the board; I don't recall off-hand which one. A better solution is to solder a very small (10 microfarad?) capacitor across two points on the U1MB. Jon has a nice photo that shows where the capacitor needs to be installed. I have not personally tried either step - I moved my U1MB to an 800XL where it's very happy. This summer I plan to get a second U1MB, try the capacitor "fix" and install that one into the troublesome 1200XL. In case you want to try this, here's Jon's photo which I saved for future reference: 1 Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 Okay, others have reported *THIS* kind of problem a few times - personally I had my U1MB in a 1200XL and experienced this same thing (settings not saving, and also occasionally scrambled character display in the menus). Super-geniuses Mathias (hias) and Jon (flashjazzcat) identified the cause of the issue as "noisy" Reset lines in some Atari boards. Some people can fix it by replacing a key 74xx logic chip on the board; I don't recall off-hand which one. A better solution is to solder a very small (10 microfarad?) capacitor across two points on the U1MB. Jon has a nice photo that shows where the capacitor needs to be installed. I have not personally tried either step - I moved my U1MB to an 800XL where it's very happy. This summer I plan to get a second U1MB, try the capacitor "fix" and install that one into the troublesome 1200XL. In case you want to try this, here's Jon's photo which I saved for future reference: U1MB_1200XL fix.jpg Thanks! Do you have a link to his solution? Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted May 6, 2017 Share Posted May 6, 2017 Thanks! Do you have a link to his solution? I don't have one saved but I described it and posted a link to Jon's photo of the capacitor. You can probably find more details with a search of this forum's posts. Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 I don't have one saved but I described it and posted a link to Jon's photo of the capacitor. You can probably find more details with a search of this forum's posts. I will thanks again! Quote Link to comment Share on other sites More sharing options...
+mytek Posted May 6, 2017 Share Posted May 6, 2017 The photo that DrVenkman posted of the U1MB reset fix is correct, but the value of the capacitor should be 100pf. - Michael 2 Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted May 6, 2017 Share Posted May 6, 2017 The photo that DrVenkman posted of the U1MB reset fix is correct, but the value of the capacitor should be 100pf. - Michael Thanks. I know I bought a big batch of tiny ceramic caps when Jon first posted about that fix but I haven't had opportunity yet to buy a second U1MB and give it a try. Couldn't remember the specific size off-hand. 1 Quote Link to comment Share on other sites More sharing options...
cerror Posted May 6, 2017 Author Share Posted May 6, 2017 Thanks. I know I bought a big batch of tiny ceramic caps when Jon first posted about that fix but I haven't had opportunity yet to buy a second U1MB and give it a try. Couldn't remember the specific size off-hand. I just read the topic, and also the PDF for updates at http://atari8.co.ukand it said 1nf ceramic capacitor. Just put the order in for a bunch of those. Gonna do the fix as soon as I get them in! Quote Link to comment Share on other sites More sharing options...
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