15 replies to this topic

[silentsolace]

I recently obtained an Atari 520 STm along with a SM124 monitor and a Golden Image DS/DD external floppy drive. The monitor and ST both seem to be in working order, but I am unfortunately having ongoing issues with the floppy drive.

When I first tested the drive it worked slightly, enough so that if I formatted a floppy in MS-DOS on a PC it would read the disk. However, if I attempted to format the disk on the ST it would work for a while and then would start to grind eventually causing the ST to crash. After trying a few different disks the floppy no longer works at all. If there is no disk in the drive the light comes on during boot and it takes nearly a full minute until the GEM desktop finally loads, the only activity seems to be a few clicks like it's trying to read a track or something. The drive is still detected but any attempt to read a disk or format crashes the system. If I try to start the system with a disk in the drive the system will crash before loading the GEM desktop. The crashes are always 2,3,4, or 11 'bombs', there doesn't seem to be any consistency or pattern to how many 'bombs' show up when it crashes.

So far the only remedy I've tried is to open the enclosure and replace the floppy drive. I obtained a 'new' (sitting on the shelf of the local computer shop for years) Sony 920Z and modified it according to information I located on atari-forum. However when this drive was installed in the enclosure it suffered from the exact issues of the original drive.

So I'm left with the ugly conclusion that there is a problem with something other than the drive itself. Does anyone have any thoughts or experience dealing with a floppy drive issue such as this? This is my only ST so unfortunately I don't have any other systems to test against.

[31336haxx0r]

According to this http://www.atarimaga...Interrupts.html those bombs mean Bus Error, Address Error, Illegal instruction and Line F trap (whatever this is). I'm under the impression this is a sign of a defective RAM.

[Official Ninja]

Have you lifted all socketed chips and re-seated them in the sockets? Could be just a bad or oxidized connection somewhere.
I would start there.

[silentsolace]

Okay, I opened the system up and I'm not entirely sure of what I'm seeing in here.



Anyway, I've started going over the chips (making a point to avoid anything related to that big expansion board so far) but nothing seems to have made any difference. Whenever the floppy is plugged in, it boots slowly or crashes if there is a disk present. System behaves fine if I unplug the floppy drive from the ST.

This seems interesting



I don't know if it has anything to do with my floppy issue, but it seems like some wires and resistors were soldered in here. I haven't a clue what their point is. It is worth noting that the red wire seems to have broken loose its connection.

[DarkLord]

It appears to be a memory expansion board of some sort (I'm guessing because I'm not familiar with it).

Okay, if this was my machine, here is what I would do. After checking and reseating any socketed chips,
as recommended earlier in this thread...if possible...I'd unplug that memory expansion board and try
booting up then. If its a memory problem with the banks on the board, you can rule it out.

Also, if you know where the red wire is supposed to go, I'd resolder it in place, then try booting. WIth
the expansion board in place, and without.

See what results you get, and maybe you can narrow down what's wrong.

HTHs.

[silentsolace]

The board is an 1987 V2 eesieST Aerco Solderless Ram board. I was hoping someone could offer useful information regarding it before I blindly start yanking it out of there. It's hooked in a few places so I don't know if I need to remove the whole thing or if something as easy as disconnecting the cables will shut it off. I would hate to fry this thing because I didn't know any better.

The red wire is a real head scratcher. It is connected to a few other things which connects up into the modulator so I'm assuming it has something to do with that. But I haven't even tested the modulator yet so I don't know what if any affect it has. I have an idea on where it should go based on an inspection of the board, but I'm not positive. So I'm not sure what to do about it. If anyone recognizes what it's hooked up to, or has any ideas on what it could be that may be helpful.

At this point I'm thinking of investing in a second ST/floppy of some sort just so I have a backup/test/reference system. It would allow me to narrow the field of possibilities a bit more.

[Fuji-Man]

My 520STm has a black wire (same as your red wire) connected only to C103 on the right side. If it is connected to C102, that is ok. The other end is connected to a resistor that is connected to a 2N3904 transistor leg. the gray cable is hook up the same here. The shifter/modulator section looks normal.

afaik, you should be able to disconnect the ribbon cables from the RAM upgrade without any issues. I'd check for bad ram and check your power supply with a meter. Also check the header next to shifter chip and MMU connections.

 silentsolace, on Wed May 23, 2012 6:51 PM, said:

Okay, I opened the system up and I'm not entirely sure of what I'm seeing in here.

DSCF4190.jpg

Anyway, I've started going over the chips (making a point to avoid anything related to that big expansion board so far) but nothing seems to have made any difference. Whenever the floppy is plugged in, it boots slowly or crashes if there is a disk present. System behaves fine if I unplug the floppy drive from the ST.

This seems interesting

DSCF4194.jpg

I don't know if it has anything to do with my floppy issue, but it seems like some wires and resistors were soldered in here. I haven't a clue what their point is. It is worth noting that the red wire seems to have broken loose its connection.

Edited by Fuji-Man, Sun Jun 3, 2012 8:47 PM.

[silentsolace]

To share the latest, I was able to obtain a second ST and tested the floppy drive. The results could not confuse me more.

The floppy drive connected to the ST, it started up with the same issues I mentioned previously, when no disk is present it takes a long time to boot. I tested it with a disk and the system did not crash when I tried to access the floppy. I then tried to format a disk - Disk drive grinded up all 80 tracks and then the system hanged - locked up solid. I reset it and the system is dead, white screen only, does not reach the GEM desktop. Bad Luck? Caused by the floppy? Lose chips?

So anyway, I pull back the first ST, the one with the memory upgrade. I connect the floppy and start it up. Goes to desktop after a minute, I put a disk in and restart it. And it comes right up. That's new. I try to open the floppy and the window pops open. I put the disk in my PC and copy some programs over. They come up fine on the ST.  It's actually working now!?

So, my second ST remains inert regardless of whether or not the floppy is plugged in. My first ST seems to be sort of working, I am not messing with it for fear I'd break it again. The only things that were done was I tried connecting it to another computer, and when the test format botched I grabbed a second disk to test with (one I tested with previously and had the same issues).

[Zogging Hell]

The long wait without a floppy is normal so don't worry about that. Should take about 30 secs for the desktop to come up. It sounds like the second disk drive is ok, and apparently so is the first ST (though I would try and work out that loose wire thing. Have you tested the memory to make sure it's actually functioning? I have an ST with a dodgy memory upgrade, which works fine even though the upgrade failed.

Second ST - Well a white screen suggests something is working. Try and reseat the socketed chips in this one, and then maybe the memory or power supply is your next port of call. If you can face opening the first ST, try removing the power supply and testing the second ST with it.

[silentsolace]

These are both early STm / ST machines. Power supply is external (I have just the one, and I'm using it for testing both), and unfortunately I have only the one (external) floppy drive which is why this behavior is annoying, as I can't really do anything with the system(s) without it.

Thanks for the info regarding the desktop wait, I wasn't sure if that was normal or not.

I know the memory is being detected, as it's reported by sysinfo. Since my floppy is now partially working, are there any programs that I could use to test the memory (like memtest86 on PC) to avoid further disassembly?

I'm planning a full tear down and investigation of the second ST. It worked briefly when I first set it up, so I'm thinking (hoping) that this is just a loose chip issue of some sort and the thing didn't spontaneously combust the second I touched it.

[Zogging Hell]

There are utilities to test the memory, I have one, but I'm working away from home a lot at the moment so its tricky to find time to track it down. There was one on the Xtra Ram (memory expansion module) utilities disk, which I think was called memtest (as well surprisingly), but there were others.

As the disk drive is external I wonder if there is a problem around the floppy port, perhaps something bent when you inserted the cable, or some of the port pins on  the motherboard have come slightly loose and need re-soldering. The slightly nasty alternative is that there was a power spike from the disk drive, and that this fed back into the ST damaging god knows what... I suppose on the positive side, most of those earlier STs have mainly socketed chips, so it might make it easier to swap them around if necessary if something has been zapped. It's not obviously physical the only way of working out what has gone wrong is to whip out the electronics gear and start testing things (which is beyond my knowledge I'm afraid).

It might also be worth checking any capacitors on the motherboard for signs of damage, as they are getting on a bit, and one might have died (also it would be worth checking the power supplies of both the ST and floppy drive as well as these are probably reaching the end of the road by now).

[silentsolace]

 Zogging Hell, on Tue Jun 5, 2012 8:53 AM, said:

As the disk drive is external I wonder if there is a problem around the floppy port, perhaps something bent when you inserted the cable, or some of the port pins on  the motherboard have come slightly loose and need re-soldering. The slightly nasty alternative is that there was a power spike from the disk drive, and that this fed back into the ST damaging god knows what... I suppose on the positive side, most of those earlier STs have mainly socketed chips, so it might make it easier to swap them around if necessary if something has been zapped. It's not obviously physical the only way of working out what has gone wrong is to whip out the electronics gear and start testing things (which is beyond my knowledge I'm afraid).

It might also be worth checking any capacitors on the motherboard for signs of damage, as they are getting on a bit, and one might have died (also it would be worth checking the power supplies of both the ST and floppy drive as well as these are probably reaching the end of the road by now).

These are basically my worst fears, that the problem is actually in the ST; damage to the chip/port/capacitors for whatever reason. I already checked, and unfortunately the WD1772 is not socketed on my ST, which means swapping it is not likely with my experience and available tools (no soldering iron, etc.) Also my electronics knowledge is only rudimentary. I can poke around with my multimeter but beyond checking for continuity and voltage I'm not going to get very far.

I'm keeping an eye out for another external floppy drive so I have a point of comparison, but I don't want to drop a lot of money on one. I was also thinking of acquiring an HxC floppy emulator, but they're kind of pricey and I would have to build an enclosure and interface for it since this enclosure may not be compatible or trustworthy.

[Fuji-Man]

I would check/swap the WD1772 and the DMA chip (C025913-xxx). The DMA might be socketed, so that is an easy check. Knowing where/what side of pond will point you in a direction to find someone to pull chips/install sockets. Zog has good point of checking with magnify glass to find solder joints that are cracked/cold and checking capacitors for leakage/bulging, etc.

I live in the Chicago area, and I have access to soldering/chip removal equipment.

 silentsolace, on Tue Jun 5, 2012 2:21 PM, said:

 Zogging Hell, on Tue Jun 5, 2012 8:53 AM, said:

As the disk drive is external I wonder if there is a problem around the floppy port, perhaps something bent when you inserted the cable, or some of the port pins on  the motherboard have come slightly loose and need re-soldering. The slightly nasty alternative is that there was a power spike from the disk drive, and that this fed back into the ST damaging god knows what... I suppose on the positive side, most of those earlier STs have mainly socketed chips, so it might make it easier to swap them around if necessary if something has been zapped. It's not obviously physical the only way of working out what has gone wrong is to whip out the electronics gear and start testing things (which is beyond my knowledge I'm afraid).

It might also be worth checking any capacitors on the motherboard for signs of damage, as they are getting on a bit, and one might have died (also it would be worth checking the power supplies of both the ST and floppy drive as well as these are probably reaching the end of the road by now).

These are basically my worst fears, that the problem is actually in the ST; damage to the chip/port/capacitors for whatever reason. I already checked, and unfortunately the WD1772 is not socketed on my ST, which means swapping it is not likely with my experience and available tools (no soldering iron, etc.) Also my electronics knowledge is only rudimentary. I can poke around with my multimeter but beyond checking for continuity and voltage I'm not going to get very far.

I'm keeping an eye out for another external floppy drive so I have a point of comparison, but I don't want to drop a lot of money on one. I was also thinking of acquiring an HxC floppy emulator, but they're kind of pricey and I would have to build an enclosure and interface for it since this enclosure may not be compatible or trustworthy.

[silentsolace]

 Fuji-Man, on Tue Jun 5, 2012 3:01 PM, said:

I would check/swap the WD1772 and the DMA chip (C025913-xxx). The DMA might be socketed, so that is an easy check. Knowing where/what side of pond will point you in a direction to find someone to pull chips/install sockets. Zog has good point of checking with magnify glass to find solder joints that are cracked/cold and checking capacitors for leakage/bulging, etc.

I live in the Chicago area, and I have access to soldering/chip removal equipment.

I might take you up on this, I live in Michigan. I've tried taking stuff to a local place I found willing to do this kind of thing, but they are still holding my Atari 7800 hostage after 3 months trying to do the s-video mod. Everytime I call or visit they say it should be done next week. Not at all reassuring so I'm not taking anything else there.

I'm going to give this system serious testing first, and if I can locate a floppy drive reasonably priced so I can be sure that will be even better.

[silentsolace]

For those who are interested, I finally resolved this issue.

The problem? Bad floppy cable.

I obtained a SF354 to use that came complete with power and fresh cable. In testing the fresh cable worked with the SF354 and the Golden Image enclosure and the floppy formatted without any errors. So far everything is operating with a clean bill of health.

[DarkLord]

Awesome, congratulations.