STe - Bad DMA Chip

[spiny]

yep those are the correct sockets

you don't need the other bits unless you want to use them, all i do is move the original resistor on the board

cool.

[blackpanther]

you can't use the DMA from an STFM

but i do have a few used GOOD DMA chips left so you may be in luck

they are £10 each plus postage

PM me if interested

DMA chip arrived today, fitted and ready for ultraSatan.

Thanks for your help

Mark

[tobias]

I have the same problem, does anybody have any more DMA chips for sale?

[Zamuel_a]

I bought my STE in 89 and never had any problems with the DMA chip. I haven't looks what version it is, but I have used a harddrive for years without any problems. What kind of problems do you get with a bad DMA chip?

[tobias]

I recently bought a STE and when I used it with the HD for the first time and copied a file from floppy to the HD it suddenly looked like this

and after reboot the HD was unreadable.

[thorsten_guenther]

You get complete data loss on the hard disk drive. BTDT - I had a faulty STE with a Vortex external case (Mega ST size, but made of metal) containing a built-in SyQuest SQ555 and a Vortex host adapter back in the early 1990s.

Thorsten

[MRAtari]

I recently bought a STE and when I used it with the HD for the first time and copied a file from floppy to the HD it suddenly looked like this

and after reboot the HD was unreadable.

i'm so glad this picture was posted as this is EXACTLEY what will happen if you use an STE with a crap DMA chip, it happened to me too using an Atari SH 205

you may be lucky, you may not, there will be no warning, it will just happen and your HD will be fxxxed

[wongck]

I recently bought a STE and when I used it with the HD for the first time and copied a file from floppy to the HD it suddenly looked like this

and after reboot the HD was unreadable.

i'm so glad this picture was posted as this is EXACTLEY what will happen if you use an STE with a crap DMA chip, it happened to me too using an Atari SH 205

you may be lucky, you may not, there will be no warning, it will just happen and your HD will be fxxxed

Well this is one sure fire way to find out if you need a new DMA chip.

[simbo]

I have the same problem, does anybody have any more DMA chips for sale?

hi toby send me by pm your postal address and ill send you one i have spare
its a working and tested system pull C398739-001A (c)atari 1990
think its £10 + post {uk £2}


here is a guide to add jumpers where the resistors are
viewtopic.php?f=74&t=17059

as for tos 2.06 techie alison can help you there
for now ive run out of 1mb eproms
but i have plenty of 4mb and 2mb types for dual { st mega st} or quad tos burns {ste mega ste and TT030{no point in quad tos for st but it can be done if you want other tos and o/s added also like emutos etc}

also plenty of 512k 28 pin types for dual tos st_f_m {mega st} very little mod {just one jumper pad to a switch}
provided you have the 74ls11 not!! fitted for 6 chip tos
{ie if you have 2 chips you need to add a 74ls11 and 6 sockets {quite easy}

if you use turned pin sockets for all ic's you will not have to strip the whole pcb out
can easily be done from the top only {all mods like this to dil chips or smd}

here is a good way to buy and use them
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... &indexURL=
£7 or so free post paypal {3days delivery i usualy find for small stuff}

http://stores.shop.ebay.co.uk/J-H-Compo ... ec0Q2em322

i use this guy's shop ALOT !!! he is quite cheep
supplies a nice set of capacitors also mostly the right size and decent maker

[Erazotropa]

Hi all,

I have the same problem as above but!.......

I have the good DMA chip (C398739-001A), en never used HDD's before.
I am now using an old SH-205 HDD that works fine on a STF with tos 1.04.

On My STE with tos 1.62 or 2.06 reading the HDD is no problem, (formatted and Partioned on a STF with tos 1.04)
Writing to the HDD seems to go ok, but reading fails! and i got scrambled data.

Personaly i dont think there is no DMA fault at all!! because:

1. ACSI port data lines are paralell to FDD controller data lines! (hmmm strange why no bad data on FDD )
2. the 74LS245 and/or 74LS244 buffer ic's are low power type ones, i will try to replace them with HC ones these days.
3. I have read some other people had same problem, but when using TOS 1.04 on the STE problem has been solved!)
Could there be a Bug in TOS 1.6x and above???

Well those are my thoughts for today

Bjorn

[Erazotropa]

Ok, well what I thought it could be, I think I was right.

For all people who have trouble with corrupted data on their HDD's,
please do the following first!!! It can spend you some bucks on getting a new DMA chip!.

Looking into the schematic:
---------------------------
For example.
If you have corrupted data on D1 to D8 of the data lines coming from the DMA chip, you will have corrupted data on the ACSI port and

also on the FDD controller. No doubt about this!.

Funny is that no one has or had mentioned corrupted data on their FDD's
That made me thinking that it could NOT be de DMA chip.

Further along the data lines are U307(74LS244) and U302(74LS245) buffers.
U307 for Control lines, and U302 for Data lines Read/Write

Since the 74LS types are low power devices...
Because of that Reading from ACSI port gives no problem because a ACSI device drives U302 data lines.
But writing data back to ACSI device is different story.
I measured with a scope that U302 has little dificulties driving High 5volt levels down to 0v levels.
On some data pins i measured 0.8v minimum!!! that is still too High for 0 volt!.
Simply because Low power shotky's dont have enouhgh strengt/current to drive high levels "in this case" to low level.
So the ACSI device can still see high level coming in, even it is low level from U302!.

Simply I Replaced both for HC or HCT types, wich draw some more current to set High or Low levels.
Now measuring 0.03v Minimum..

And voila, No corruption anymore!!!

So if you have data corruption please replace U302 and U307 for HC or HCT types first!!!




Bjorn - Eraz

[Hempsa]

I have problems removing the faulty chip. I couldn't solder it off, so i cut off it's legs, but I stil can't get it out. Is there somekind of glue between it and the motherboard?

edit: Revision CA4003290 ----- REV ------

[Chandler]

there is no glue!

possibly the chip has stuck to the PCB from heat

make sure you have cut all the legs as close to the chip as possible, for this you need to look through a magnifying glass and i don't care how good your eyes are! you need to look closely

and be very careful when cutting those legs as you can damage the PCB

if you are sure all legs are cut then push down on the chip at each end (with the mobo on a flat surafce) and try and "rock it" if not then gently and i mean GENTLY prise up one end with a flat bladed screwdriver or similar being careful not to break any resistors around the chip

good luck

[Hempsa]

Thanks, "rocking" it from both ends did the job. Next, getting the new one in. I guess I have solder wires from old chip's remaining legs to new chip.

[Chandler]

Thanks, "rocking" it from both ends did the job. Next, getting the new one in. I guess I have solder wires from old chip's remaining legs to new chip.

WHAT!

NO! you remove the old legs from the holes with a solder sucker or if you're really clever hold the iron on the solder and with some tiny pliers pull the old leg out, when i say "pull" i mean in the lightest possible way

if you pull it too hard you'll rip out the track! so be GENTLE

again you need to be doing this under a magnifying glass

when you've got them all out clean up the holes nicely and pop in the new chip, solder a leg at each corner making sure the chip is flat then turn over the mobo and solder up all the new legs

simples

[Hempsa]

All right, got it changed and running, no problems so far. Bought a 40-pin socket for the chip and soldered it to motherboard.

[Chandler]

yep using a socket actually is a good idea in case you had problems with the chip

you can only desolder and re solder in a chip so many times before the mobo tracks fall apart

[MiggyMog]

I have Previously had problems with corrupted data/ partitions when using Satandisk/Ultrasatan, I have checked my STE and it has the 'good' DMA chip.

I have reccently started using a different PSU with UltraSatan and thankfully have not had the corruption problems so far.

[wongck]

I have Previously had problems with corrupted data/ partitions when using Satandisk/Ultrasatan, I have checked my STE and it has the 'good' DMA chip.

I have reccently started using a different PSU with UltraSatan and thankfully have not had the corruption problems so far.

I read from the other thread that US had some issues with the bad DMA, which he is trying to fix.
So your issue was because of bad power supply & not the DMA?

[Erazotropa]

Low power on the 74LS'ses change them into HC's and see for you self..

No body seems to try this! :S

[Jookie]

Low power on the 74LS'ses change them into HC's and see for you self..

No body seems to try this! :S

Well, it surely wouldn't help me.
See http://joo.kie.sk/ultrasatan/steproblem/

[kini_calderon]

Hi all! as a new member of the forum, I salutate you. My nickname is Kini_Calderon and I'm from Europe (Spain).

I was wanting to join the Atari forum for a long time... So I Just joined. I decided to do because I need help with a problematic STE.

I am a fan of Atari since I had the first one, back on the days of 1991's. My first one was(and is) an Atari 512 STfm with a "Rainbow Spanish Tos". (Sometimes I think, What happening if Atari machines had evolved?, What could they do in nowadays?, More than an x86 machine, of course, )

As I said before, I have the "one" problematic STE with de bad DMA chip "C025913-38". I noticed it when I was testing the wonderful "UltraSatan". Resuming the tests I did before I noticed, I could find that was issue only occurrs in the STE, I tested the Ultrasatan for hours I my others two STfm's machines (512 and 1024) without any errors. But when I insert it on STE, "aways" deleted the first partition on first reboot and so on.

I contacted via e-mail with Jookie and Mikro, and they said that the problem was the bad DMA chip. I think so. In fact after the explanations and test of Jookie I read before in his www.

I wish the oportunity to buy a "good" working DMA chip, so if anybody have one or know someone who has one, I will eternaly grateful. Send me a PM.

Thank you all!

Pd: Sorry for my poor english, I am spanish. I am trying to do better day to day.

[simbo]

I have Previously had problems with corrupted data/ partitions when using Satandisk/Ultrasatan, I have checked my STE and it has the 'good' DMA chip.

I have reccently started using a different PSU with UltraSatan and thankfully have not had the corruption problems so far.

change the buffer ic's dm74LS244 /245 for better ones like hc or hct
this way the port becomes more tollerant of other levels of transition

the satandisk uses 3.3v transitions and is TTL compatable
but this comaptability only extends to HCT HC or later types
i would use HCT or better types

i always change the supply voltage to these ic's to 3.3v using a clamp zener or a small 3 pin regulation ic
then use ACT types but they will also run at 5v VCC i change the vcc anyway

like
74ACT245 u302
74ACT244 u307
74ACT74 u308

most important is U305
i use a 74F06 here {not used in the TT i wonder why and why there is some timing issues with its dma more than its packet loss}

change these 4 ic's BEFORE using satandisk on any dma on ste or mega ste or the 3 on the TT030
the STFM works a different way and only U51 and maybe the dma
{but knowone reports problems with stfm's that use the same dma controller as the so called 'bad ' one }

=={wake up and change the associated logic for more complient with later ic's like satandisk used and smell the coffee}
or expect problems
although it will work with most as is
the 'bad' dma doesnt exist !!!!!
i feel its just 'bad' 74 logic especialy U 305 as its just a 7406 and mega crap in ste and mega ste and not there in the TT030
and this also 'cleans up' the floppy data in mega /ste

so use 74ACT logic only for all three chips !!! now
and an F type for the other
leaving the vcc @5v is less hasle and just as good !!!!!!!!
and dont go changing the dma .. chip

finaly
if you have a dma issue thats still unresolved
you can place a 1n4148 in series with the vcc supply pin of the dma chip
ive seen this mod being done in machines many times and it works
if you still have issues which i dought!!!

[Jookie]

the 'bad' dma doesnt exist !!!!!
i feel its just 'bad' 74 logic especialy U 305 as its just a 7406 and mega crap

I disagree, please read more here:
http://joo.kie.sk/ultrasatan/steproblem/

[Chandler]

the DMA issue of early STE's is real and is why Atari changed the chip to a completely different number, some chips even had the letters BUG on them! (whether that was mean't to mean anyting or just a fluke i don't know)

having personal experience myself with a dodgy DMA wiping out an Atari branded hard drive i would NEVER use any kind of hard drive/satan disk with an dodgy DMA STE