Help - no floppy showing when in GEM

[RichAtari]

I have dug out my old 520 STFM (upgraded to 1Mb) to find it switches on, but the floppy does not work. It boots reasonably quickly to the gem desktop but has no disk or trash can icons. I have tried a new drive (pre configured for ST). Have tried floppy cable both ways round as it stated it needed inverting. The light comes on the drive as the machine powers and goes out shortly after. No Amber light shows on the keyboard. If the cable is inverted the drive light stays on all the time.  Anyone any ideas?

[Johnnii360]

Hi!

 

I have the same issue but additional issues with the floppy drive.

 

First a small prehistory: At this time I want to resurrect my ATARI 1040 STFM. First I re-capped my SC1224 monitor and then the 1040 STFM. In after the first test boot the drive is done some delayed single read actions. But it's similar if it's a floppy in the drive or not. So I dismounted the drive and checked connections and the PCB. I found nothing so I've putted it in back and wanted to try something. Now the drive isn't do something any more. So I checked the PCB and all solder points with a magnifier and found a broken solder point. So I fixed the point and putted the drive back in. Now the LED is light a short time as normal on the drive and the keyboard and the platter is spinning. But the platter doesn't stop spinning any more. It's also similar if it's a floppy in or not. I also re-soldered all solder points on the main PCB (TDK-T4IV) but it changed nothing.

 

My floppy drive is an Atari/Chinon D357 720K FDD (TDK-T4IV). It was bought in the 1990's as replacement for the broken stock FDD that my father damaged because he tried to get out a stuck floppy and had destroyed the head.

 

In fact that the electrolytic capacitors are very old I will re-cap the drive next days. And I hope it will fix the issue. But maybe someone know this issue and got some tips or infos about this for me and RichAtari?

[ParanoidLittleMan]

It is known fact that without disk in floppy drive there is longer delay until Desktop shows.  Then, if there is disk in drive, but file DESKTOP.INF is corrupted it may be that will get empty Desktop. And in this case most likely: there is HW failure, and that causes this problem.

 

What can do:  try with another drive, good one. If it works fine, can read and write to disks then it is clear case.

If works not with good drive (what is properly connected, powered) then failure is in Atari. And that's longer story.

 

To add, that any floppy drive is now very old. Buying other, trying to fix - may be expensive, questionable how useful it is, how long will last.

More and more people goes on replacement solution. Ton of threads about it here ...

[snarkdluG]

Checked PSU? Good 5V?

[Johnnii360]

2 hours ago, snarkdluG said:

Checked PSU? Good 5V?

In my case it's also fresh re-capped. But I will also check it.

[Johnnii360]

Hello again!

 

I checked today the voltages. A proper +5V and +12V voltages is coming from the PSU. On the FDD power plug is a voltage of 4.7V without FDD connected. When I connect the FDD it's 4.6V.

 

I also recapped the FDD today and at the first test I got the same result as already mentioned. The LED on the FDD and the Keyboard lights up for approx 2-3 seconds and only the platter is permanently spinning. So I disconnected the FDD and traced a bit of contact spray in the floppy cable connector. After that the FDD is now recognized again. But now the same issue: It doesn't read floppys any more and I have no clue why.

 

Here a video of it (stored on my private cloud): https://cloud.jotoma.de/f/8269f19c37ab4ec2bebc/

 

I know the best thing is to try another FDD but I have only a 1.4MB FDD here. Exxos sells a Diagnostic Cart but I don't know if I should buy this first or a new used FDD. And I also know that there are some alternatives but I want to keep the floppy feeling. What do you recommend me?

 

Ah btw. I have schematics of my 1040 STFM.

Edited May 26, 2021 by Johnnii360

[ParanoidLittleMan]

Those head jumps in and out indicate that track seek works not - it can't read track number from disk. Last chance is to clean drive heads, use another floppy disk - some are in so bad shape that magnetic surface wears off, and that's what goes on heads - so get rid of if see signs of wearing. I had such problem couple times.

And 1.44 drive can work in DD mode. Actually, in some ST only in that mode. But question is is it Atari compatible - if not need to change some line connections. Like swapping lines 10 and 12 . Then ensure that HD/DD line is properly connected - to GND or +5V - sorry, I don't keep it in my head so need to look about it online.

Can get some clue here: http://atari.8bitchip.info/flomodam.html

And yes, there is little harder problem to solve - disk change detection, but that is not relevant for start - it will work with not Atari compatible drive without that mod, only danger is when changing not copy protected disks.

[Johnnii360]

@ParanoidLittleMan Hmm... Okay I think I give up. So I bought the caps in vain. I think I buy a Gotek. Any experiences with it or something you can tell me about it?

 

Btw. I tested already some different disks but it's always the same issue.