traindriver69 Posted December 18, 2014 Share Posted December 18, 2014 Hi all Just installed the 48k atari 400 upgrade from best electronics and it is working but its causing a lot of interference on the tv screen anyone got an ideas please. Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted December 18, 2014 Share Posted December 18, 2014 I've done many of these, and never had a problem. Clean the rf connectors,inside and out, with a q-tip and rubbing alcohol. Also check the solder on the connectors. Something may have come loose. Maybe try a new cable. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 18, 2014 Author Share Posted December 18, 2014 hi checked the solder on the wires seems fine tried a different rf cable but still the same. Quote Link to comment Share on other sites More sharing options...
russg Posted December 18, 2014 Share Posted December 18, 2014 (edited) Hi all Just installed the 48k atari 400 upgrade from best electronics and it is working but its causing a lot of interference on the tv screen anyone got an ideas please. Don't know. But is that the 48k expansion kit, requiring modifying existing 16k memory card, or the 48k factory plug in expansion board? I was thinking, if you can touch the drams, see if any are running hot. Does the 400 have a channel select switch? Maybe try other channel. Wiggle the channel switch and see if that effects the display. You're running with the case put together? Might stop interference with case assembled. Edited December 18, 2014 by russg Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 18, 2014 Author Share Posted December 18, 2014 hi its the ram expansion kit from best electronics just put it all back together still the same thing. i tried typing a program in through basic as i wanted to test my printer out with the 400 and every time i pressed enter the distortion got worse and when i ran the program it was terrible. thing is if i plug in my old 16k ram card which is faulty hence the reason i brought the 48k kit I get a perfect blue screen with no interference. does anyone know what the four wires do which i have soldered in trying to figure out why i am getting this problem. Quote Link to comment Share on other sites More sharing options...
tep392 Posted December 18, 2014 Share Posted December 18, 2014 Try calling Brad at Best. He might have heard of this problem. He's pretty good with tech issues. I did a quick search and found a post from someone else who had video noise after a 48k upgrade. I also seem to recall reading in an old ANALOG magazine review about some 48k boards causing noise. I have an Intech 48k board in mine and don't have any issues with video. Quote Link to comment Share on other sites More sharing options...
+Stephen Posted December 18, 2014 Share Posted December 18, 2014 I've not had or heard of this issue before. I installed an Atari 48k expansion board in a 400 not too long ago, and it didn't cause issues. One thing I would check, is the power supply. It could be that the new RAM is drawing more current than the PS can supply. If I am not mistaken, those 400/800 and 1050 supplies came in 15VoltAmp and 31VoltAmp models. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 18, 2014 Author Share Posted December 18, 2014 I have two power supplies a 27va and a 31va but both give the same problem I was thinking it could be a power issue, problem is I am in the uk and getting hold of parts is not cheap where in the usa they are cheap and plentiful It's cost me a small fortune already and I still not got a problem free 400 Quote Link to comment Share on other sites More sharing options...
tep392 Posted December 18, 2014 Share Posted December 18, 2014 Here's an excerpt from a review in ANALOG Computing for the Intech 48k board. It mentions video issues related to the power usage of the earlier boards. Quote Link to comment Share on other sites More sharing options...
tep392 Posted December 18, 2014 Share Posted December 18, 2014 I have two power supplies a 27va and a 31va but both give the same problem I was thinking it could be a power issue, problem is I am in the uk and getting hold of parts is not cheap where in the usa they are cheap and plentiful It's cost me a small fortune already and I still not got a problem free 400 I still recommend calling Brad to see if he knows of any solutions. Quote Link to comment Share on other sites More sharing options...
BillC Posted December 18, 2014 Share Posted December 18, 2014 I have two power supplies a 27va and a 31va but both give the same problem I was thinking it could be a power issue, problem is I am in the uk and getting hold of parts is not cheap where in the usa they are cheap and plentiful It's cost me a small fortune already and I still not got a problem free 400 The Atari 48K upgrade for the 400 uses 4164 RAM chips, they use less power than the 4116 but I believe they do draw more power from +5V since they don't drawn any power from -5V/+12V. You said in the other thread that the +5V output was at 4.89V with the old RAM board, what is it with the new 48K board? The Doctor had already suggested rechecking the voltages with the new board, and examining the capacitors for obvious problems, in that thread. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 19, 2014 Author Share Posted December 19, 2014 I have rechecked the voltage points and they are no different with the new ramboard in Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted December 19, 2014 Share Posted December 19, 2014 Do you have a picture of the noise? Little white lines one character wide randomly appearing on the screen? If so, try a new ANTIC. Bob Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 19, 2014 Author Share Posted December 19, 2014 Definitely not the antic because when I ordered the 48k expansion kit also ordered a new cpu board and tried it in the 400 with no difference Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 20, 2014 Author Share Posted December 20, 2014 not the best pictures but the one with the worst interference is when the program is running. Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted December 20, 2014 Share Posted December 20, 2014 Try a different TV? I'm really reaching here. Just try cleaning everything up the best you can...and I mean everything. It has worked for me in the past. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted December 20, 2014 Share Posted December 20, 2014 (edited) wow that's a mess! something just isn't right about that at all... couldn't hurt to try another screen like paul mentioned... check rf cords.. and video circuit caps and transistors after that... is ther a clear pic mod for 400? check out this video.. https://www.youtube.com/watch?v=uBqqfqjb-x8 ram goes nearest cartridge port, os goes towards back..chips face away from cart port towards back... don't forget to trim the spacer or you may damage connector... make sure no cables have been pinched or flattened.. including rf.. inspect all caps... Edited December 20, 2014 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
1050 Posted December 21, 2014 Share Posted December 21, 2014 Probably a very long shot, but I have nothing else to contribute. This looks to me like all the symptoms of inadequate decoupling going on. Please read this: Selecting Decoupling Capacitors for Atmel’s PLDs http://www.atmel.com/images/doc0484.pdf Although this application note is for PLDs and this is not that, ram chips also have large switching spikes during refresh in particular. You may have an entire lot of substandard decoupling capacitors mounted on that board from the factory. I would get some .22uf chip form and piggyback them onto the current caps just to eliminate this possibility. Perhaps on the backside of the board between the current leads and their associated solder mounds? Reflowing the power connections and ground plane using good flux would be the first thing to do. Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted December 21, 2014 Share Posted December 21, 2014 There are no video circuits on the memory board, so it probably comes thru the power supply or you have shorted two nets together. Or, you lost a ground on the memory board? You need to try a new upgrade board or scope the circuits. Triple check the added wiring. Nasty... Bob Quote Link to comment Share on other sites More sharing options...
Marius Posted December 21, 2014 Share Posted December 21, 2014 Have had some issues too on my 400, and in fact… the screen is not 100% perfect yet, but it is ok here. I found my RF modulator 'walking away' during the first 10 minutes. At a certain moment it stabilizes and then it stays on a certain frequency. I have to adjust my TV set the first 10 minutes, it does auto-fine-tune but only when i tell the TV to do so, so I have to do this 2 or 3 times within these 10 minutes. There is some other interference too… that is especially on the borders of the screen and on the border of totally black (the edges) and actual screen, but this is a very little problem. Are you sure you did not break anything or hurt anything while opening the computer? The RF cable has only one ROUTE that is correct. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 21, 2014 Author Share Posted December 21, 2014 No everything is how it should be to be honest I only got the 48k expansion because my 16k ram board does not work if I could get hold of another 16k ram board just to get the 400 working properly I would do.but the problem is in the usa they are cheap and easy to come by over here in the uk I can't find any and to buy one from the U.S. with postage is a hell of a lot of money unless anyone on here has one and can get it to me without a great expense. Quote Link to comment Share on other sites More sharing options...
+wood_jl Posted December 21, 2014 Share Posted December 21, 2014 Here's an excerpt from a review in ANALOG Computing for the Intech 48k board. It mentions video issues related to the power usage of the earlier boards. 48kvideonoise.jpg My *first* computer was an Atari 400. I paid $190 (!!!!!) in the early 80s for an Intec 48K upgrade (at Art's Video Mart in Anchorage, AK for any old-time die-hards from the time and place) and it just blew power supply fuses, one after another. I've since had Atari-brand upgrades with no problem. Quote Link to comment Share on other sites More sharing options...
Marius Posted December 21, 2014 Share Posted December 21, 2014 I had an original Atari 400 48K memory upgrade for my Atari 400. No issue with power or whatsoever. I guess TopicStarter has the same upgrade. It's from Best electronics, in a white-black box, with original documentation from atari. Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 21, 2014 Share Posted December 21, 2014 This does not look like the usual digital noise interference. It looks more "analog." Could it be a problem in the RF modulator itself? Or its shield? Is there visible corrosion outside the box or in? Are the solder connections sound? Would you be willing to do a composite video mod? You have already invested money and effort and have made good progress. You just need to gain success! Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 22, 2014 Author Share Posted December 22, 2014 If it is the rf modulator why when the 16k ram is plugged in (even though it is faulty) there is no interference. Quote Link to comment Share on other sites More sharing options...
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