Bad Ste DMA
Sim
A few weeks ago someone posted the chip number of the Dodgey DMA
chip for STe. Mine is a first revision STe, the chip number is c025913-38 so
can someone confirm wether this is the suspect part number.
If this is the bad DMA chip, is there anything I can do about it
other than replace it? IIRC the problems only occur after a few hours of
use, so this suggests to me that, it's a simple heating problem. Could
this be cured by having a fan or heat sink? And how come the problem
dosen`t affect either the floppy disc drive or DMA sound chip? I`ve never
had corrupt floppies or bad dma sound even after running my Ste for 10s
of hours in a warm room.
____ ____ _ _ _ Simon Hammett - py4...@bath.ac.uk _ _ _ ____ ____
| Part time programmer and maintainer of the STAssembler Homepage |
| http://www.bath.ac.uk/~py4sdh/index.html |
-------------------------------------------------------------------
John Collis
> A few weeks ago someone posted the chip number of the Dodgey DMA
>chip for STe. Mine is a first revision STe, the chip number is c025913-38 so
>can someone confirm wether this is the suspect part number.
As I'm the guy who asked the questions a few weeks ago, I've included
summaries of what I learnt! I've quoted replies that I got with the
'|' character. I hope you can follow all of this! Apologies to those I
have quoted but I haven't included attributions.
C025913-38 is the 'suspect' chip. Here are some of the quotes:
|The new layout of the STE did not like the old DMA chips C025913-38
|this must be replaced with a C398739-001A..
|Some people here seem to think that fitting a very old C025913-38
|will work but I have never tried it.....
|The symptom is two bytes missing everywhere. You might get garbled
|files and/or garbled directories, with all the filenames shifted by
|two characters.
|The fail safe method: If your STE doesn't have a C398739-001A or
|C398789-001 DMA chip, you have the "dangerous" one in there. Replace
|by the former of the two Atari chips mentioned (the latter is the PLCC
|case version used on later STE boards).
> If this is the bad DMA chip, is there anything I can do about it
>other than replace it? IIRC the problems only occur after a few hours of
>use, so this suggests to me that, it's a simple heating problem. Could
>this be cured by having a fan or heat sink?
Good question, I asked this question and got varying replies:
|In my case the problem was there even if the computer was started the
|first time for the day (cool) so I don't think a fan will help. But
|then again, that's how it was for me.
|On my spare 1040STf, I have hard drive write problems. I tried moving
|the DMA chips from a good ST to the bad in an effort to troubleshoot.
|With the "good" chips installed onto the "bad" motherboard, I still
|had write problems. The "bad" ST would work fine for around fifteen
|minutes then the write errors would kick in. I would have to
|powerdown the "bad" ST for around 30 minutes for it to write.
|A much easier solution would be to fix a small IC heatsink on top of
|it. This can be gunged on using heatsink compound (if you're not going
|to be moving your ST around too much) or better still, glued on using
|heat conductive glue (available from RS Components in UK and probably
|many other electronics stores).
|IC heatsinks are easy to get and cheap. Look in an electronics shop or
|catalogue. Use the biggest that will fit in the case. Forced air
|cooling probably isn't necessary.
|All Silicon is affected by heat, the input threasholded gets changed
|so it can now see the noise...
>And how come the problem
>dosen`t affect either the floppy disc drive or DMA sound chip? I`ve never
>had corrupt floppies or bad dma sound even after running my Ste for 10s
>of hours in a warm room.
I don't know this. I can also remember a year or more ago, someone
suggesting that the problem wasn't so much to do with the actual chip,
but was to do with the motherboard design and some problems with
tolereances for a timing threshold. A certain batch of chips showed
this up when dealing with disk throughput, whereas the later batch of
chips didn't stress the design so much. I personally don't have the
techinical know-how to know whether this is an extremely useful idea
or a load of rubbish. It sounds good anyway! :-))
I have a chip here which is one of the 'suspect' chips, that I know
has come from a STE that ran a Hard-Drive with no problems for a
couple of years. So things aren't necessarily bad. Problem is, you
don't know until you try!! The answer I got to that was:
|Well that all depends, I would not trust it 100%, I have seen DMA
|chips work for 12 hours but not for 24 hours..
I hope all this is of some help!
Cheers,
John
-=-=-=-=-=-=-=-=-=-=- John Collis at home -=-=-=-=-=-=-=-=-=-=-
jo...@albemuth.equinox.gen.nz or jo...@southern.co.nz
Claes Holmerup
Hello Simon,
> A few weeks ago someone posted the chip number of the Dodgey DMA
> chip for STe. Mine is a first revision STe, the chip number is c025913-
> 38 so
> can someone confirm wether this is the suspect part number.
It is, in fact, the DMA chip that shouldn't be in an STe.
> If this is the bad DMA chip, is there anything I can do about it
> other than replace it? IIRC the problems only occur after a few hours
> of use, so this suggests to me that, it's a simple heating problem.
> Could this be cured by having a fan or heat sink? And how come the
> problem dosen`t affect either the floppy disc drive or DMA sound chip?
> I`ve never had corrupt floppies or bad dma sound even after running my
> Ste for 10s of hours in a warm room.
This is probably not the only explanaition, since - in my experience -the DMA
problems can occour any time You try to write to the hard drive.
A way to be certain should be to copy lots of files, deleting some and copy
more to the drive, and after that defragment the drive. Now You will probably
have a totally messed up hard drive. Most of the time it's enough to try to
save the desktop two times, since this changes the file and for some reason
that seems to be the problem.
I don't remember the part number for the fully functional DMA chip (Ihave a
Falcon nowadays so there's no need for me to remember), but I think it was
something like: 38..38-001 (I can't seem to remember the two digits between the
38's - my memory is all fragmented...). Your service center should know about
it when You ask them.
Kindest regards
Claes
fidonet: 2:200/136.5
e-mail: cl...@dada.ct.se
( UUCP Dialup connection )
Roger Sheppard..
>Hi all,
>
> A few weeks ago someone posted the chip number of the Dodgey DMA
>
>other than replace it? IIRC the problems only occur after a few hours of
>use, so this suggests to me that, it's a simple heating problem. Could
>this be cured by having a fan or heat sink? And how come the problem
>dosen`t affect either the floppy disc drive or DMA sound chip? I`ve never
>had corrupt floppies or bad dma sound even after running my Ste for 10s
>of hours in a warm room.
Yes that is the Bad one...
Very very risky, just get the New chip if you can find one...
Atari UK has stated that all the faulty DMA chips were replaced...??
Or is this the normal lyes that come from Atari...??
*******************************************************************************
* R. W. Sheppard Internet shepp...@kosmos.wcc.govt.nz *
* +64-4298-7249 GEnie r.she...@genie.geis.com *
*******************************************************************************
steve wells
] of hours in a warm room.
I get crackly DMA sound, but don't have any drive troubles. I've got one
of the last model STes off the production line, but it had a faulty PSU,
which I swapped for one from an old STFM, it worked better on the FM
than on the E, and the FM one works quite happily on this E. The RF-audio
output was faulty, but fixed among other minor problems by Roger Sheppard
(who, although many will say annoying, is a good diagnostic electrician :).
I wasn't too happy, but when the machine only cost me about $US-250 brand
new, I can't complain _too_ much, especially as the people who sold it
to me ceased to exist a short while after I bought it :)
Anyway, apart from the crackly DMA sound (even through the monitor, so it
isn't my stereo system), the machine runs fine now. I wouldn't have a clue
what chip it is, anyone know where the DMA chip is at on a late revision
STe? (The type with metal screw-holes molded into the base!)
WEL...@IX.WCC.GOVT.NZ I am in no way affiliated with the Government or City
Steve Wells. Council! - Maintainer of the Generation-X Comics FAQ!
Roland Givan
> than replace it? IIRC the problems only occur after a few hours of
> use, so this suggests to me that, it's a simple heating problem. Could
> this be cured by having a fan or heat sink? And how come the problem
IMO extra ventalation/cooling is always worth a try. I saved my TT a trip
back to the repair shop by fitting an external PSU and leaving the original
fan in case. The video circuitry now no longer flickers after warming up.
:-)
Roland.
@CiX
Veikko Vanamo
>Hi all,
>
> A few weeks ago someone posted the chip number of the Dodgey DMA
>chip for STe. Mine is a first revision STe, the chip number is c025913-38 so
>can someone confirm wether this is the suspect part number.
In my STE was faulty DMA-chip and the number was c025613-38.
>
> If this is the bad DMA chip, is there anything I can do about it
>other than replace it? IIRC the problems only occur after a few hours of
>use, so this suggests to me that, it's a simple heating problem. Could
>this be cured by having a fan or heat sink? And how come the problem
>dosen`t affect either the floppy disc drive or DMA sound chip? I`ve never
>had corrupt floppies or bad dma sound even after running my Ste for 10s
>of hours in a warm room.
If You are going to use Hard Drives with your STE I recommend
that You change the chip / test it with Hard Drive first.
In my STE everything seems to be ok until I use Hard Drive.
As soon as my STE warmed up (and chips too) problems started.
Atari (Finnish service) didn't belive me that the problem was
in that chip. (I lost much monay for that).
I went to other store where we tried this:
- Opened the machine.
- Started the HD & Machine.
- Put the HD to work (filecopy etc...)(...it could take hours...)
- When DMA-chip warmed up and problems occur we
sprayed cooling-spray to the chip.
- It work again, so We know that it was that chip which was faulty.
- We changed the chip to other one ( C398739-001A...)
- Today it works fine with and without HD!
--
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_| _| Veikko Vanamo
_/ InterNet E-Mail : _/ _| _/| _/_/_/_/_/_/_/_/_/_/_/_/_>
_/ VVA...@tays.fi (E-Mail only !)_/ _| _/_| _/ Lahtomaenkatu 3 B 38
_/ mi...@sci.fi ( Use this one !!)_/ _|_/ _|_/ 33580 Tampere
/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ _|/ _|/ FINLAND
Arno Welzel
>Hi all,
>
> A few weeks ago someone posted the chip number of the Dodgey DMA
>chip for STe. Mine is a first revision STe, the chip number is c025913-38 so
>can someone confirm wether this is the suspect part number.
IIRC this is the faulty chip, as my DMA chip number is C398789-001, and
i use one of the latest STEs wich has no DMA problems.
> If this is the bad DMA chip, is there anything I can do about it
>other than replace it? IIRC the problems only occur after a few hours of
>use, so this suggests to me that, it's a simple heating problem. Could
>this be cured by having a fan or heat sink? And how come the problem
>dosen`t affect either the floppy disc drive or DMA sound chip? I`ve never
>had corrupt floppies or bad dma sound even after running my Ste for 10s
>of hours in a warm room.
The problem is, that the faulty DMA chip can not handle fast harddisks.
Floppy and/or DMA sound works well - also with the faulty chip.
Ciao...
--
Arno Welzel (a...@zaphot.augusta.de)
Kim Andersen
>Hi all,
>
> A few weeks ago someone posted the chip number of the Dodgey DMA
>chip for STe. Mine is a first revision STe, the chip number is c025913-38 so
>can someone confirm wether this is the suspect part number.
It is the bad DMA chip, sorry.
>
> If this is the bad DMA chip, is there anything I can do about it
>other than replace it? IIRC the problems only occur after a few hours of
>use, so this suggests to me that, it's a simple heating problem. Could
>this be cured by having a fan or heat sink? And how come the problem
>dosen`t affect either the floppy disc drive or DMA sound chip? I`ve never
>had corrupt floppies or bad dma sound even after running my Ste for 10s
>of hours in a warm room.
Because the faulty part in the DMA only concern the harddisk. As you already
suspected it's a heating problem, (at least that how it looks). But you can't
do anything else than changed the chip. I doubt a fan would make it
possible/realiable to use it at all.
I really understand you. I got a faulty one myself. (got two STE's and
got two faulty ones.. Talk about luck. One has been fixed though, the other
is beeing used without Hd).
Greets
Kim
--
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