abraXXious Posted April 26, 2013 Share Posted April 26, 2013 Hey guys, I recently purchased a replacement DMA chip for an Atari STE which has a buggy (or so I thought) DMA chip installed. The chip arrived today, however it is marked "CO25913-38 PH23-030" which from a couple of searches I have done is supposed to be one of the BAD DMA chips - whats worse is that it is exactly the same chip (CO25913-38 PH23-030) as whats already in my STE which is causing corruption and is supposedly one of the Bad/faulty DMA Chips. Can someone please confirm if this chip is a known GOOD DMA, or BAD DMA? Thanks. 1 Quote Link to comment Share on other sites More sharing options...
frank.lukas Posted April 26, 2013 Share Posted April 26, 2013 520/1040STE / Mega STE / TT Good = C398739-001 (A) Bad = C025913-38A 1 Quote Link to comment Share on other sites More sharing options...
GadgetUK Posted April 26, 2013 Share Posted April 26, 2013 (edited) 520/1040STE / Mega STE / TT Good = C398739-001 (A) Bad = C025913-38A ^ spot on! I've just looked at a photo of my STe DMA chip which I know works properly as I've used it with my Ultra Satan and I have C398739-001. Edited April 26, 2013 by GadgetUK Quote Link to comment Share on other sites More sharing options...
abraXXious Posted April 26, 2013 Author Share Posted April 26, 2013 Hi guys, thanks for the help. So what you are saying is that the DMA Chip I have been sent to replace my bad DMA is simply another bad DMA? Apparently this DMA Chip, CO25913-38 PH23-030, is found in STs and works fine in them, however on the STE it is known as a bad DMA. The seller says it comes down to the date they were produced. So in other words, any CO25913-38 PH23-030 found in an SE from factory is a bad DMA, however if you pull a CO25913-38 PH23-030 from an ST and put it in an STE it is fine as these were produced BEFORE the batch of bad ones found in the early STEs. Is this correct? 1 Quote Link to comment Share on other sites More sharing options...
GadgetUK Posted April 26, 2013 Share Posted April 26, 2013 Hmmmm, I will be honest, it's possible but that's not what I've seen in wikis etc. Why else did the part number change. And for the record the ST used a different DMA chip, which didn't have the fault. Personally I think the seller might be pulling a fast one, but that's just my opinion. Quote Link to comment Share on other sites More sharing options...
abraXXious Posted April 27, 2013 Author Share Posted April 27, 2013 Thanks for your help GadgetUK. The seller says the chip was pulled from a Mega ST.... but I have been told by two different people now (plus I suspected myself) that the DMA used in the Mega ST is the same as that used in the standard ST and so are not compatible with the STE range. Is this correct? Can a Mega ST DMA Chip be used in an STE? Quote Link to comment Share on other sites More sharing options...
frank.lukas Posted April 27, 2013 Share Posted April 27, 2013 Can a Mega ST DMA Chip be used in an STE? no, the C025913-38A is for the Atari ST range and the C398739-001 (A) is for Atari STE range The seller says the chip was pulled from a Mega ST.... but I have been told by two different people now (plus I suspected myself) that the DMA used in the Mega ST is the same as that used in the standard ST and so are not compatible with the STE range. Is this correct? The DMA Chip from a Atari ST (520/1040 or Mega ST) is not compatible with the STE and Mega STE range ... Quote Link to comment Share on other sites More sharing options...
Cyprian Posted April 29, 2013 Share Posted April 29, 2013 The DMA Chip from a Atari ST (520/1040 or Mega ST) is not compatible with the STE and Mega STE range ... but both chips looks the same. do you know, where we can find STE DMA pinout description or what is difference between them? Quote Link to comment Share on other sites More sharing options...
frank.lukas Posted April 29, 2013 Share Posted April 29, 2013 The Pinout is the same ... The STE DMA Chip in a 1040STE is a 40pin DIL and the Mega STE and Atari TT a PLCC Pinout ... Quote Link to comment Share on other sites More sharing options...
abraXXious Posted April 30, 2013 Author Share Posted April 30, 2013 Okiez, so the packaging of the STE and ST are the same and the pinouts are the same, but the internals are different and hence not compatible? Quote Link to comment Share on other sites More sharing options...
bluemonday Posted October 4, 2014 Share Posted October 4, 2014 I've opened up my 1040 STE to see if there's a good or bad DMA chip. Inside I saw the attached. The numbers on the chip don't seem to match those of a good or bad chip. Does anyone know what these chips are and if it's a good DMA chip? Perhaps someone has already replaced the chip? Quote Link to comment Share on other sites More sharing options...
GadgetUK Posted October 4, 2014 Share Posted October 4, 2014 Based on the fact the STe came out in 1989 and the stamp on that chip is 1991 I would assume that it's a good DMA chip. Quote Link to comment Share on other sites More sharing options...
Junosix Posted October 5, 2014 Share Posted October 5, 2014 The chip with 1991 on is the Ajax floppy controller chip, the DMA chip (small square one on the right with 1990 on it) is one of the "good" ones. Quote Link to comment Share on other sites More sharing options...
GadgetUK Posted October 5, 2014 Share Posted October 5, 2014 Doh!!! I was reading upside down and assuming it was the DMA based off STFM package size etc. Egg on my face lol! Quote Link to comment Share on other sites More sharing options...
bartek030 Posted October 5, 2014 Share Posted October 5, 2014 I've opened up my 1040 STE to see if there's a good or bad DMA chip. Inside I saw the attached. The numbers on the chip don't seem to match those of a good or bad chip. Does anyone know what these chips are and if it's a good DMA chip? Perhaps someone has already replaced the chip? Nobody replaced it. It's the last revision STE motherboard with plcc DMA (C398739-001). All plcc DMA are GOOD. 1 Quote Link to comment Share on other sites More sharing options...
bluemonday Posted October 5, 2014 Share Posted October 5, 2014 Thanks for the clarification, that's great! Quote Link to comment Share on other sites More sharing options...
exxosuk Posted October 7, 2014 Share Posted October 7, 2014 Please can people try my DMA fix before buying new DMA chips! http://exxos.www.idnet.com/IMPULSE/atari/last/DMAfix/index.htm 1 Quote Link to comment Share on other sites More sharing options...
TheAtariKing Posted October 25, 2014 Share Posted October 25, 2014 The DMA chip in my Atari 1040STe is a 40 pins IC with the number C398739-001A printed on it. So, from what I am reading here, I guess I have a good DMA chip. Quote Link to comment Share on other sites More sharing options...
GroovyDrifter Posted August 10, 2015 Share Posted August 10, 2015 (edited) Sorry for bumping this year old thread, but with old computers, issues appear more often as time passes, so... Please can people try my DMA fix before buying new DMA chips! http://exxos.www.idnet.com/IMPULSE/atari/last/DMAfix/index.htm I've just done it with no luck I've removed and socketed the DMA ic and then applied the fix over it (so in case I find a good DMA chip I can replace it without taking the full computer apart again). It is an Atari 520STE, motherboard CA4003290, bought from UK, with the same fix applied that this one from Atari Wiki: The DMA chip is the C025913-38 one. I have a STFM with one of those working perfect, and a spare STFM motherboard with that same chip where I try things, also working with no issues. This board, this particular unit at least, is very problematic... I had to replace the colour transistors as sometimes one colour, usually blue, faded slowly and disappeared, leaving a Yellow/Green desktop; replaced all four simm sockets (and installed 4MB RAM)... and still gives sometimes bombs at boot time (yes, I'm the guy that contacted you by email regarding the Mitsumi SR98 schematics). I know it's not a power issue as the PSU has been recapped (used the values and make you suggest in your web) and the chopper transistor and rectifier bridge upgraded... and tried two different ones (both fixed). It surprised me that the ROM were already socketed and that one of the ROM/EPROM type configuration jumpers was missing, and fixed with a permanent board trace (I replaced those with jumpers), none of my previous STE had this (I have two more, I like to fix and upgrade computers, not a reseller of any kind..) I've seen that I've not been the first one trying to fix this board as there is burnt flux over several components pads. He replaced some of the capacitors... two under the PSU were too tall an the PSU tilted over them, I changed them with tantalum ones as they are shorter and now it sits over the four legs. I'll probably try to swap the DMA ic with the one in the spare STFM board to make a crossed test. I'll usually replace all elec. capacitors first, but this Ataris have too many. If I had a spare DMA chip I'll surely recap it before replacing the DMA (one or the other or both will fix it) but otherwise it feels like a 90% probability of throwing more money away... Edited August 10, 2015 by GroovyDrifter Quote Link to comment Share on other sites More sharing options...
exxosuk Posted August 10, 2015 Share Posted August 10, 2015 There is a similar topic over at Atari-forum also. I think the caps I suggest only work for gigifile drive. UltraSatan design is different, so probably needs different values. I assume you used 100pF in parallel on your DMA ? Try 200pf and 100pf and see if that change anything. I tried the caps on my STE and did not matter if caps were there or not, did not matter which DMA version either. I have been hearing reports of UltraSatan not working for some time now. I really starting to think there are faulty batches of them out there. In anycase, I got a ultrasatan a few weeks ago, I am just waiting for my cable to arrive. So then I will repeat peoples tests to see if I can replicate the fault. 1 Quote Link to comment Share on other sites More sharing options...
exxosuk Posted August 17, 2015 Share Posted August 17, 2015 (edited) My cable finally arrived I have installed HD9 on my US and done some copying files from A: to C: and all seems good so far. I am using a STFM with -38 DMA. I connected up a STE with -38 DMA. Tried HD9 and US driver by PP. Copied files from A: to C:, then back to A: again with both drivers. Did tests with PP's speed test program, So far everything seems good to me. Edited August 17, 2015 by exxosuk Quote Link to comment Share on other sites More sharing options...
exxosuk Posted August 17, 2015 Share Posted August 17, 2015 (edited) So I started copying A: to folders on C:. Then copied all those folders into another folder on C:, and copying again I started to get errors. There is about 250 files in about 80 folders so far which I am copying about. Sometimes AHTP94 says 0 errors, and other times, many errors. 918 bytes error... Now the card is totally trashed , so formatting to try with HD9 just to make sure same problems happen again... So been fighting with this for past half hour, HD9 after partition, they just vanished into corruption, and yet HD9 was working fine to start with. So next test I swapped out the STE PSU for one I have updated. Now I have partitioned the drive and copying files from A: back into some test folders to see what happens. Also during the mix, US managed to stop my keyboard from working.. After I turned off/on US it started working ok again.. bizarre.. I have also noticed the floppy light and keyboard drive light seem to stay on all the time. Edited August 17, 2015 by exxosuk Quote Link to comment Share on other sites More sharing options...
exxosuk Posted August 17, 2015 Share Posted August 17, 2015 So currently I am using HD9 and updated PSU, same STE with -38 DMA. So far it has gone way past the amount of files I had before on the drive and I am still copying files about. As I had the problems copying to and from the hard drive, It is currently what I am doing. I will keep copying files about until the 200MB partition is full.. Quote Link to comment Share on other sites More sharing options...
exxosuk Posted August 17, 2015 Share Posted August 17, 2015 So been going over a hour now. No problems. I think if it was going to trip up, it would have done so by now. I have copied around way more files than before when it went wrong. I will try with PP driver just to make sure, but this looks like when the PSU has a problem, the DMA suffers faults first. I already came to that conclusion some time ago and posted about it "somewhere". Quote Link to comment Share on other sites More sharing options...
exxosuk Posted August 17, 2015 Share Posted August 17, 2015 I tried PP driver, and after a while got this problem, but no other problems with hardware. So, I pretty much conclude UltraSatan and STE & -38DMA works perfectly well with a good ST PSU. I have been asking that is someone swap out a -38 DMA out of a STE for a 001 and it solve problem, that they send me the -38 for testing here. I mention this every few months but nobdy send one so far. So unless I see a buggy DMA chip personally I still think there is no problem with the -38 DMA in the STE. 1 Quote Link to comment Share on other sites More sharing options...
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