UKRetrogamer Posted December 22, 2014 Share Posted December 22, 2014 I'm beginning to wonder if this is PAL/50Hz related. I'm in the UK too and bought the same kit from Best a couple of years ago. Once fitted, the RF/TV output went bad on my 400 as well. I just assumed I'd screwed up somewhere and put my 400 away as dead/unusable as I don't have the electronics knowledge to trouble-shoot something like this. I'm reasonably competent with a soldering iron, so I'm convinced I've got everything where it should be with no splashes/bridges, etc. I could remove the 48K kit but that'd leave me with a 16k 400 again. The RAM expansion works just fine - I'm able to load programs from my SDrive Nuxx which (IIRC) isn't possible in just 16K so I'd like to see someone come up with a solution/workaround to this. Because of the fragile keyboard cable, I'm not overly keen on constant disassembly of my 400. As an extension of this "upgrade" project, I also bought a composite-mod kit from another source here in the UK but having looked at the soldering work on this kit, I'm not too keen to fit this into my 400 in case it compounds the problem, rather than resolving it. I'll be watching this thread with interest. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 22, 2014 Author Share Posted December 22, 2014 when you say bad are your rf output the same as i am showing in the pics i posted Quote Link to comment Share on other sites More sharing options...
UKRetrogamer Posted December 22, 2014 Share Posted December 22, 2014 Pretty much EXACTLY like that. If my 400 weren't buried, I'd take some photos to prove it. The RF output degraded so much after installing the RAM, I was convinced I'd broke the machine while doing the upgrade. Your thread now has me convinced there's something else going on. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 22, 2014 Author Share Posted December 22, 2014 Does anyone know if these 48k expansion ram cards are ment for pal machines and does anyone know why the four wires are needed for this card,this is driving me crazy and just trying to figure out why this is happening. Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 24, 2014 Share Posted December 24, 2014 Did you fully reassemble the metal shield after installing the 48K RAM? You said you got a new CPU board too. Does the noise change between old and new CPU board? The four wires are required to bring select and deselect signals for addressing 48K because the 400 was designed for only 32K RAM. The board should be fine for PAL 400s. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 24, 2014 Author Share Posted December 24, 2014 I have tried it all ways with metal shield,without metal shield with new CPU board with old CPU board can't get any difference Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted December 24, 2014 Share Posted December 24, 2014 Try a new RCA cable got the video. Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted December 24, 2014 Share Posted December 24, 2014 For the video...damn iPad Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 24, 2014 Share Posted December 24, 2014 The post below has a photo of an Intec board. Is that the one you have? I don't see a single large bypass cap on it at all, just the smaller ones near each chip. Most boards use electrolytic caps near the edge connector for power filtering. Perhaps you could add one? Just be careful of the polarity. http://atariage.com/forums/topic/207429-atari-400-incognito-like-upgrade/page-5?do=findComment&comment=2939447 Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 24, 2014 Share Posted December 24, 2014 Correction: Atari boards don't have large caps but they do have a 0.001 uF cap between +5V and ground near the edge connector. Perhaps you could transplant one from your 16K board? Happy Christmas! Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted December 24, 2014 Share Posted December 24, 2014 Does it have the RF cable wrapped around a toroid ring inside the case? Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 26, 2014 Author Share Posted December 26, 2014 yes it has its toroid ring basically this upgrade was made by atari and for some reason its causing major interference problems if i was to remove some of the memory chips from the board would it still work and use less power just to fault find if its a power drain problem. Quote Link to comment Share on other sites More sharing options...
russg Posted December 26, 2014 Share Posted December 26, 2014 yes it has its toroid ring basically this upgrade was made by atari and for some reason its causing major interference problems if i was to remove some of the memory chips from the board would it still work and use less power just to fault find if its a power drain problem. The drams are 1 bit wide. 64k of single bits wide. It takes eight of them to make a byte, so removing a dram the computer will not work. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted December 27, 2014 Share Posted December 27, 2014 Only other idea it to do the 48k hack,,, http://atariage.com/forums/topic/109732-atari-400-48k-memory-upgrade/?p=1326701 on the original memory board that does not cause interference... Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted December 27, 2014 Share Posted December 27, 2014 The 48K board does not connect -5 and +12. I do not have a schematic for a PAL machine, but you may need to jumper the power pins. A stock RAM board connects pin 20 to pin X and pin 21 to pin Y. You might try that. Use a 100 ohm resistor to connect the pins and see if the video improves. If it does, try a 47 ohm, then a 10 ohm. Or, a .1ufd capacitor. You can also try the 'Finger Generator' and just touch each of those pins with your finger while it is running - see what happens. (use a piece of wire for a probe) If nothing much happens, it's probably not the power circuits... Bob Quote Link to comment Share on other sites More sharing options...
tep392 Posted December 27, 2014 Share Posted December 27, 2014 (edited) Did you do a visual check of the electrolytic caps on the power board to make sure none have leaked? Look for residue at the base of the cap. If one of those go bad, it can allow increase noise in the power circuit. I think you already checked the voltages, but you would miss the noise if you used a multimeter. Edited December 27, 2014 by tep392 Quote Link to comment Share on other sites More sharing options...
tep392 Posted December 27, 2014 Share Posted December 27, 2014 (edited) not the best pictures but the one with the worst interference is when the program is running. I was looking at these pics again, and it looks like you were typing the program into the memo pad. So no program, other than memo pad, was running. The only difference between the last photo and the others would be how much text you have on the screen. I'm still suspicious of ANTIC or GTIA. edit: or a bad video cable or cable connector. Edited December 27, 2014 by tep392 Quote Link to comment Share on other sites More sharing options...
Joey Z Posted December 28, 2014 Share Posted December 28, 2014 Did you do a visual check of the electrolytic caps on the power board to make sure none have leaked? Look for residue at the base of the cap. If one of those go bad, it can allow increase noise in the power circuit. I think you already checked the voltages, but you would miss the noise if you used a multimeter. I was reading the post waiting for SOMEONE to suggest that it could be PSU caps. with this memory board, it might draw more power causing the filtering to be less effective if the caps are bad. I think you could pinpoint the 5V cap in the 400/800 Field service manual which is available online in PDF form. Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 28, 2014 Share Posted December 28, 2014 Take C523 from the old RAM board and solder it here: 1 Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted December 28, 2014 Share Posted December 28, 2014 What does your board look like? This? Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 28, 2014 Author Share Posted December 28, 2014 yes that is my ram board Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 28, 2014 Share Posted December 28, 2014 Sorry, thought you said Intec board. Never mind. Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 29, 2014 Share Posted December 29, 2014 Your other thread says you have an 800 too. You could put one of its 16K RAM boards into your 400 and check for noise. You could even put your new 48K board into your 800 with mods from this thread: http://atariage.com/forums/topic/185500-using-the-atari-400-48k-board-in-the-800/ Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 30, 2014 Author Share Posted December 30, 2014 sorry the other one is an 800xl Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 30, 2014 Share Posted December 30, 2014 Ah. Never mind. Again. Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.