520STE weird floppy disk drive problem

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520STE weird floppy disk drive problem

Postby kokkiklhs » Fri Oct 07, 2016 7:15 pm

Hello people!
Relatively noob with the ST range here, but very old and experienced with retrocomputing, in general...

I recently acquired a 520STE, came to me working (with a little picture distortion on RF), but with an almost dead floppy drive! The drive is Newtronics (Mitsumi) D357T.
I first managed to load a couple of Automation game disks that I wrote to real floppies using my PC and STDISK utility, but loading was not always successful.
Opened it up and realized that the little ribbon that connects the upper head to the drive's main PCB was kind of cut, trying to fix it made it worse... so now, the drive is dead and unusable, beyond any repair! :(

Had a couple of spare 1.44 floppy drives (Samsung SFD 321B and Mitsumi D359M3D) and made the modifications required for use with the ST and followed carefully the instructions of reversing the ribbon cable etc. So what's the problem, I hear you say...

Both drives do not boot as expected, they just seem to read the disks for a couple of seconds, the machines turns to GEM afterwards. I can open the disk directory, but ALL the folder names and filenames are corrupt (e.g. AUTG instead of AUTO folder and so on). All exec files return with TOS Error #35, but I can read the contents of some non-exec files in ASCII form. Tried to format some disks (old and brand-new HD and DD disks), both drives refuse to format (step motor bangs 5-6 times, but ends with messages about drive not ready or write protected, no progress at all with the format bar of the GEM window). The same with copy...

What I have tried so far:
-Turned the little trimmer inside the PSU to the extreme right position, got a little improvement with picture quality but nothing else changed.
-Changed the original floppy ribbon cable with a new and longer one, exactly the same symptoms...
-Removed and reseated all soceted ICs, after having cleaned the sockets with contact spray.
-Re-soldered the bottom of the ribbon connection AND the FDC chip on the STE board, still the same.
-Re-soldered all the capacitors inside the PSU.
-Checked the DC voltages on floppy power connector, they seem to be correct.
-Also tried to feed power to the floppy drives from an external ATX PSU.
-Made further modifications to both 1.44 floppy drives for use with Amiga and tried them, they both worked perfectly with reading/formatting/writing/diskchange.
-Last but not least, I borrowed a good working SF314 from a friend and tried with its original mechanism, still the same results.

The only thing left for me to suspect is bad capacitors in the PSU (they SEEM to be good, though, and some DC measurements I already did seem to be OK), but it's not easy for me to find replacements here. And otherwise the machine seems to be working well... So before trying to replace the capacitors, I ask for your opinions.

Any help would be precious...
:cheers:

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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Sat Oct 08, 2016 9:18 am

Update:
Swapped RAM SIMMs (in case of partial malfunction), also gave full power (to the whole machine circuitry, not only the disk drive) from a fresh and strong external ATX PSU, still exactly the same, no improvement at all... so I guess it's NOT the original PSU capacitors, as I suspected... :evil:

I include a picture (rather low quality due to RF usage but in fact image is quite stable) of what happens when I open the disk directory.
N.B. that the disks are 100% ok, I also formatted a DOS 720k from WinXP and put a single .PRG inside to see what happens with the Atari side, still corrupted filename and inability to execute the .PRG... :roll:
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Re: 520STE weird floppy disk drive problem

Postby AtariZoll » Sat Oct 08, 2016 10:35 am

May be DMA chip, WDC1772 or U305 error. It is worth to replace electrolyth capacitors in PSU. DC measuring is not good enough. Even of that's not what makes this error.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Sat Oct 08, 2016 12:06 pm

AtariZoll wrote:May be DMA chip, WDC1772 or U305 error. It is worth to replace electrolyth capacitors in PSU. DC measuring is not good enough. Even of that's not what makes this error.


Thanks for the suggestions... I shall definitely replace the capacitors as soon as I figure out the problem...
BUT, my question again is:
Is it possible to normally boot with it's own drive, put away for several days (after destroying the drive) and then produce this error with all other proven-to-be-good drives? Could the DMA, FDC or 7406 (U305) die within a few days and WITHOUT powering up the machine meanwhile?
:roll:

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Re: 520STE weird floppy disk drive problem

Postby AtariZoll » Sat Oct 08, 2016 12:21 pm

I think that it already started to be bad when you was in stage " but loading was not always successful." . So, not related with damaging of drive.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Sat Oct 08, 2016 6:49 pm

Good point!
I'll first try to change some of the surrounding capacitors! How about C305, which goes to the FDC chip, or C304 which goes to 7406? Which are the proper values of these?
Any other suspects??

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Re: 520STE weird floppy disk drive problem

Postby dlfrsilver » Sun Oct 09, 2016 12:57 am

Change the PSU capacitors, then change also the bigger ones on the motherboard, and check if this enhances the whole thing.
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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Sun Oct 09, 2016 6:49 am

dlfrsilver wrote:Change the PSU capacitors, then change also the bigger ones on the motherboard, and check if this enhances the whole thing.


When you say the bigger ones, would you suggest some specific ones, probably related to this particular problem? There's a bloody lot of electrolytic capacitors on the board and I wouldn't know from which to start! :mrgreen:

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Re: 520STE weird floppy disk drive problem

Postby dlfrsilver » Sun Oct 09, 2016 1:55 pm

kokkiklhs wrote:
dlfrsilver wrote:Change the PSU capacitors, then change also the bigger ones on the motherboard, and check if this enhances the whole thing.


When you say the bigger ones, would you suggest some specific ones, probably related to this particular problem? There's a bloody lot of electrolytic capacitors on the board and I wouldn't know from which to start! :mrgreen:


There are 2 caps more biggers than all the ones present on the motherboard.

They are not radial (vertical ones), but axial (horizontal ones).

Let me illustrate :
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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Sun Oct 09, 2016 4:04 pm

Thanks, man!! I will give it a try ASAP!!
:cheers:

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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Mon Oct 10, 2016 4:47 pm

dlfrsilver wrote:Change the PSU capacitors, then change also the bigger ones on the motherboard, and check if this enhances the whole thing.


I changed the 2 bigger capacitors, as you suggested, I also changed C204+C205 near the DMA chip, also unsoldered the 7406 (U305), put a socket and a fresh IC, no difference at all... what the heck????
Think it's time to throw the whole thing off the window!!! :twisted:

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Re: 520STE weird floppy disk drive problem

Postby czietz » Mon Oct 10, 2016 5:39 pm

Read about exxos' long investigation into DMA chip issues (and some possible solution ideas) here: http://www.exxoshost.co.uk/atari/last/DMAfix/

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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Mon Oct 10, 2016 7:16 pm

Wow, thanks..!!!
And I thought that the ST range were reliable machines...
I guess I won't spend more time with this one, I'm totally frustrated. I'd better go for another one and keep this one for spares...

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Re: 520STE weird floppy disk drive problem

Postby KLund1 » Mon Oct 10, 2016 10:55 pm

ST's are very reliable, if it has been kept in good condition it's whole life. Sadly that is not the case for most. As you are now seeing.
There is a whole lot written here about FD in ST's. Mostly about using a HD FD in place of a 720K FD. I've tried many, but met with little success.
You obviously have much more EE knowledge than I. But my experience with ST's is to replace FD with the EXACT same model as the failed unit. but they are getting harder and harder to come by.
There are other solutions then a standard FD. There is a FD sized unit that uses flash drives as the media, also Ultra-Satan Disk is my preferred go to solution. There are many others. Exxox webstore is a good place to find parts that are tested. Lotherek's (sp?) web store is also a great place. There are others.
Keep us posted on your progress.
Good Luck!
UPDATED: Falcon 030(FX-1)(CF int & removable SD), MSTE 4+PS3000 4160STE 2.06+HDFD STacy4-internal-USD 1040STFM+I.B.Driver-5.25"FDD 1040STF 1040ST 520ST-AdSpeed 400-48k 800+810x2+820+822+825+830+835+850, 800XL+IndusGT 600XL 130XE+XF551x2 Portfolio 1200XL APE(Warp+32in1 OS SuperVideo 2.1 256k RAMBO)+1050x2 USD'd+SIO2PC, PC1+PCH204+PCM124+PCF554x2

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Re: 520STE weird floppy disk drive problem

Postby dlfrsilver » Tue Oct 11, 2016 8:22 am

kokkiklhs wrote:
dlfrsilver wrote:Change the PSU capacitors, then change also the bigger ones on the motherboard, and check if this enhances the whole thing.


I changed the 2 bigger capacitors, as you suggested, I also changed C204+C205 near the DMA chip, also unsoldered the 7406 (U305), put a socket and a fresh IC, no difference at all... what the heck????
Think it's time to throw the whole thing off the window!!! :twisted:


I have a question about your hardware for soldering/desoldering : do you have and use liquid flux ?

I ask, because i have noticed that when i did my own work on my 520 & 1040 STE, without flux the solder was not filling the holes correctly.

Once i worked again on them with flux, it went like a charm.

The next step, if you used flux to resolder, and if it all went good, would be to change the DMA chip. After changing the capacitors on my PSU and also on the motherboards, that's what i did. Now both machines are more stable.
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Re: 520STE weird floppy disk drive problem

Postby kokkiklhs » Tue Oct 11, 2016 8:36 pm

KLund1 wrote:ST's are very reliable, if it has been kept in good condition it's whole life. Sadly that is not the case for most. As you are now seeing.
There is a whole lot written here about FD in ST's. Mostly about using a HD FD in place of a 720K FD. I've tried many, but met with little success.
You obviously have much more EE knowledge than I. But my experience with ST's is to replace FD with the EXACT same model as the failed unit. but they are getting harder and harder to come by.
There are other solutions then a standard FD. There is a FD sized unit that uses flash drives as the media, also Ultra-Satan Disk is my preferred go to solution. There are many others. Exxox webstore is a good place to find parts that are tested. Lotherek's (sp?) web store is also a great place. There are others.
Keep us posted on your progress.
Good Luck!


Thanks, man!!! I was planning to get a gotek USB floppy emulator flashed for ST, but since this problem appeared, I cannot be sure whether this could be really usable on this particular machine of mine, or not... I guess I will stop my efforts for now, but if I have any news in the future, I shall let you all know!!

dlfrsilver wrote:I have a question about your hardware for soldering/desoldering : do you have and use liquid flux ?

I ask, because i have noticed that when i did my own work on my 520 & 1040 STE, without flux the solder was not filling the holes correctly.

Once i worked again on them with flux, it went like a charm.

The next step, if you used flux to resolder, and if it all went good, would be to change the DMA chip. After changing the capacitors on my PSU and also on the motherboards, that's what i did. Now both machines are more stable.


Yes, I do use flux, always! Once I realize which is the problem, I'd gladly change a DMA chip, but now, since I have a non-working machine, I'd first have to fix it! The funny thing will be if the problem itself IS the DMA chip, but I will try easier workouts before I proceed with replacing it!!
Thank you all for your interest and help so far!!

:cheers:

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Re: 520STE weird floppy disk drive problem

Postby russcky » Tue Feb 21, 2017 3:47 am

kokkiklhs wrote:Hello people!
Relatively noob with the ST range here, but very old and experienced with retrocomputing, in general...

I recently acquired a 520STE, came to me working (with a little picture distortion on RF), but with an almost dead floppy drive! The drive is Newtronics (Mitsumi) D357T.
I first managed to load a couple of Automation game disks that I wrote to real floppies using my PC and STDISK utility, but loading was not always successful.
Opened it up and realized that the little ribbon that connects the upper head to the drive's main PCB was kind of cut, trying to fix it made it worse... so now, the drive is dead and unusable, beyond any repair! :(

Had a couple of spare 1.44 floppy drives (Samsung SFD 321B and Mitsumi D359M3D) and made the modifications required for use with the ST and followed carefully the instructions of reversing the ribbon cable etc. So what's the problem, I hear you say...

Both drives do not boot as expected, they just seem to read the disks for a couple of seconds, the machines turns to GEM afterwards. I can open the disk directory, but ALL the folder names and filenames are corrupt (e.g. AUTG instead of AUTO folder and so on). All exec files return with TOS Error #35, but I can read the contents of some non-exec files in ASCII form. Tried to format some disks (old and brand-new HD and DD disks), both drives refuse to format (step motor bangs 5-6 times, but ends with messages about drive not ready or write protected, no progress at all with the format bar of the GEM window). The same with copy...

What I have tried so far:
-Turned the little trimmer inside the PSU to the extreme right position, got a little improvement with picture quality but nothing else changed.
-Changed the original floppy ribbon cable with a new and longer one, exactly the same symptoms...
-Removed and reseated all soceted ICs, after having cleaned the sockets with contact spray.
-Re-soldered the bottom of the ribbon connection AND the FDC chip on the STE board, still the same.
-Re-soldered all the capacitors inside the PSU.
-Checked the DC voltages on floppy power connector, they seem to be correct.
-Also tried to feed power to the floppy drives from an external ATX PSU.
-Made further modifications to both 1.44 floppy drives for use with Amiga and tried them, they both worked perfectly with reading/formatting/writing/diskchange.
-Last but not least, I borrowed a good working SF314 from a friend and tried with its original mechanism, still the same results.

The only thing left for me to suspect is bad capacitors in the PSU (they SEEM to be good, though, and some DC measurements I already did seem to be OK), but it's not easy for me to find replacements here. And otherwise the machine seems to be working well... So before trying to replace the capacitors, I ask for your opinions.

Any help would be precious...
:cheers:


Sorry you have had such problems, I agree... the ST is a very sturdy and reliable machine. I had similar problems that I tried everything to diagnose and ultimately I was able to replace the drive with a new $8 ebay floppy drive and all works fine now.

I am no ST expert but here is the details of my recent ordeal replacing my floppy if this helps:
http://fetchrex.com/2017/02/12/oh-no-at ... ve-issues/

Good Luck!

Russ

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Re: 520STE weird floppy disk drive problem

Postby Quickie » Fri Jul 27, 2018 7:35 am

Hi there,

I'm so sad not to have found this thread before!
I have EXACTLY the same problems as kokkiklhs stated, in an almost-identical hardware: a 1040STE and some noise on the RF image (which is noticeable by seeing some noisy vertical lines).
The problem in essence is the same: this computer came to me with non-working FDD.
The floppy icon is displayed on TOS, however when you try to access to it, the floppy led blinks for 2-3 seconds...and then nothing happens. Not even the typical "Drive is not responding" error. Nothing.

- Tested the floppy on another 520STFM -> Worked like a charm
- Replaced the FDD for a Gotek with FF 0.9.18a -> Same behavior. Seems to work, but accessing to the floppy does not. Note, that I tested this Gotek drive with several usb sticks on the other working 520STFM and works fine.
- Tried to format a .dsk on the Gotek. The process starts and sometimes it even finishes, but afterwards the "floppy is not responding" error appears.
Funny thing here is that this image gets modified somehow, as the content stored on it is lost when read on another ST.

Image

- Replaced the U305 -> 74LS06 -> Same symptoms
- Replaced the U301 -> WD1772 IC for a new VLSI 1772 -> Same symptoms
- Performed a full recap of the motherboard -> Same symptoms (altough seems that there was a slight improvement of the RF video quality)
- Performed a full recap of the PSU -> Same problem
- Replaced the PSU with the STFM512 PSU -> Same behavior.
- Replaced the floppy cable and replaced it with a PC floppy socket + shiny new floppy drive cable -> No difference.

Image

So, I'm stuck with no ideas left and a lot of frustration as I have spent tons of hours on it and I resist to leave it as a "dead" machine.

I have an oscylloscope, so any hint or help is welcome and I would be happy to post here the results if this means that can be useful for someone else.

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Re: 520STE weird floppy disk drive problem

Postby ijor » Fri Jul 27, 2018 4:27 pm

Quickie wrote:- Replaced the U305 -> 74LS06 -> Same symptoms
- Replaced the U301 -> WD1772 IC for a new VLSI 1772 -> Same symptoms
- Performed a full recap of the motherboard -> Same symptoms (altough seems that there was a slight improvement of the RF video quality)
- Performed a full recap of the PSU -> Same problem
- Replaced the PSU with the STFM512 PSU -> Same behavior.
- Replaced the floppy cable and replaced it with a PC floppy socket + shiny new floppy drive cable -> No difference.
...
So, I'm stuck with no ideas left and a lot of frustration as I have spent tons of hours on it and I resist to leave it as a "dead" machine.

I have an oscylloscope, so any hint or help is welcome and I would be happy to post here the results if this means that can be useful for someone else.


As recommended to the OP, read exxos' research on DMA issues. But considering all you have done already, I'd start replacing the DMA chip. Which DMA chip do you have?

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Re: 520STE weird floppy disk drive problem

Postby Quickie » Fri Jul 27, 2018 8:45 pm

Thanks for replying.

Yes, the DMA chip is the usual suspect and I think it would be the only missing ic to be replaced.

This particular one is a : C025913-38 PH23-030 9L2 05.
Unfortunately those chips are virtually impossible to find (at least in Spain).

I read Exxos' excelent DMA article some months ago and following his advice I even bought a 68k HC version.
Noneless to say thay I tried swapping it (this is a Freecale one) for the stock Motorola and the result was the same.

I even piggybacked the LS U206 and U306 and the 74LS245 with no improvements.

So, in brief resume, if anybody knows where I could obtain the mentioned DMA chip and if this could be a plausible case where the DMA chip can be probed with the osc to check this malfunction I would be grateful.

Cheers.

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Re: 520STE weird floppy disk drive problem

Postby ijor » Sat Jul 28, 2018 1:05 am

DMA chips are not that hard to find. May be they are very rare in Spain, but you can probably find sellers on other countries. Ask in the wanted forum.

In the meantime you might try other Exxos recommendations that involve adding or replacing the resistor pullups on the data and dma buses.

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Re: 520STE weird floppy disk drive problem

Postby Quickie » Sat Jul 28, 2018 3:13 am

Hi,

Found the exact same DMA ic on eBay and now it's on the way. Let's cross fingers.
Regarding the resistor pullups, weren't they discussed to be solutions for data corruption on hd's rather than floppy drives?

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Re: 520STE weird floppy disk drive problem

Postby ijor » Sat Jul 28, 2018 5:06 pm

I would try to get a later DMA chip, not the exact same one you have.

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Re: 520STE weird floppy disk drive problem

Postby Quickie » Tue Sep 11, 2018 7:52 pm

Hi,

Finally the DMA chip arrived and I had time to perform the replacement.
I removed the old DMA chip, soldered a 40 pin socket and placed the new DMA chip, which is a C025913-38 PH23-030 like the previous one.

Actions performed:

- Re-tested the floppy cable pin by pin. All continuity measurements are OK.
- Replaced the CPU for a MC68HC000FN8 just in case
- Inserted the new DMA IC...and suprise, it isn't working but a new error message is displayed:

"Your output device is not receiving data"

Image

If I swap the original DMA chip, the behavior is different, being the same as the beggining, the drive is shown on TOS but clicking on it does not make anything nor shows any error message.

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Re: 520STE weird floppy disk drive problem

Postby ijor » Thu Sep 13, 2018 12:57 am

Quickie wrote:Finally the DMA chip arrived and I had time to perform the replacement.
I removed the old DMA chip, soldered a 40 pin socket and placed the new DMA chip, which is a C025913-38 PH23-030 like the previous one.

Actions performed:

- Re-tested the floppy cable pin by pin. All continuity measurements are OK.
- Replaced the CPU for a MC68HC000FN8 just in case
- Inserted the new DMA IC...and suprise, it isn't working but a new error message is displayed:


As I said, replacing the DMA for the same version wasn't probably the best idea. As we have seen in different cases, the DMA issue is not simple and not always requires the same solution.

It is possible that the problem is something else, even at the board. But now that you soldered a socket, trying a different DMA chip version is probably the first thing that you should try.


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