520st stopped recognising my gotek

[Noah199]

Well, the bare wire is for shure something I'll take care of, but for now, it does work. It's solid core wire and therefore pretty stiff and the exposed parts are not that close to the other pins. I also tested for shorts multiple times, as mentioned before.

I actually don't have any seperate flux at hand, I just use flux core solder, as I don't do that much soldering. The solder I used is about 30 years old, and while I do have new lead-free solder, I just find the old leaded stuff to be easier to use. The black crud you see all over the place is the flux from that solder. While it may be corrosive, I don't think it caused any damage in the 2 weeks or so that it's been applied, as all of the signals can be traced from the st's port to the gotek just fine.

[ijor]

Yes, I'm now using a straight cable.

Note that you do might need to twist the cable. I'm not talking about a cable with a few wires twisted as in used in a PC. With the ST you sometimes need to twist the whole cable. This is because Atari branded drives have the connector upside now in relation to a standard PC drive. When you connect a Gotek to an ST with internal drive, you must twist the cable. I don't know in your case. It depends on how the adapter was built.

The thing i find weird now is that despite receiving track 0, data and index signals just fine, there are no step signals on the FDC.

On reset you should see step pulses no matter what. Disconnect the Gotek and check the step signal at the FDC (not at the 4706 which at the high state it would be floating).

Even if the step signals are too brief for me to measure them with my analog scope

The step pulse is 4us wide. Any scope should easily capture the pulse without problems.

...but it now completely stopped recognizing the disk drive and its activity light would stay dark.

Drive selection is performed by a different chip, not by the FDC. Check the DS0 signal. If DS0 is not asserted you have a problem beyond the FDC and the 7406.

[Noah199]

Note that you do might need to twist the cable. I'm not talking about a cable with a few wires twisted as in used in a PC. With the ST you sometimes need to twist the whole cable. This is because Atari branded drives have the connector upside now in relation to a standard PC drive. When you connect a Gotek to an ST with internal drive, you must twist the cable. I don't know in your case. It depends on how the adapter was built.

I don't think I need to twist the whole cable, as I can trace all of the st's floppy port pins to the appropriate gotek pins.

On reset you should see step pulses no matter what. Disconnect the Gotek and check the step signal at the FDC (not at the 4706 which at the high state it would be floating).

With the gotek unplugged, the step signal remains low.

The step pulse is 4us wide. Any scope should easily capture the pulse without problems.

I was more worried about me not seeing them on the scope's screen as they happen, as the scope can only display a signal live, the trigger is only used to "sync" the signal. (at least I think so)

Drive selection is performed by a different chip, not by the FDC. Check the DS0 signal. If DS0 is not asserted you have a problem beyond the FDC and the 7406.

DS0 is fine

[rubber_jonnie]

Well, the bare wire is for shure something I'll take care of, but for now, it does work. It's solid core wire and therefore pretty stiff and the exposed parts are not that close to the other pins. I also tested for shorts multiple times, as mentioned before.

To be clear, it may not be shorted now, but it may have done at some point, there is no way of knowing.

I actually don't have any seperate flux at hand, I just use flux core solder, as I don't do that much soldering. The solder I used is about 30 years old, and while I do have new lead-free solder, I just find the old leaded stuff to be easier to use. The black crud you see all over the place is the flux from that solder. While it may be corrosive, I don't think it caused any damage in the 2 weeks or so that it's been applied, as all of the signals can be traced from the st's port to the gotek just fine.

I asked because it looked burned very like plumbers flux. If it's resin cored flux you should be OK, I'd suggest that you clean it with IPA and review it. Honestly, I suspect that the adapter has failed, even if it buzzes out ok, you just don't know how it'll behave when a signal passes.

Flux can be corrosive regardless of how long it's present, so even in 2 weeks there could be damage, so I wouldn't make assumptions.

My options would be to at least try with a real floppy drive set to DS0 and a diag cartridge that will let you run consistent repeatable tests.

[Noah199]

So, I decided to connect the st to a monitor to observe what it would do at this point. I don't have a monitor on my electronics bench, so I just expected it to do the same thing it did last time I had tested it with a monitor, which was to boot to an empty desktop. But instead, it did the following:
Keep in mind that the led on the Gotek is currently controlled by DS0

• Half a second or so after reset: Garbage on screen cleans up, screen goes grey, Gotek led lights up

• 5 Seconds after reset: Gotek led turns off

• 10 Seconds after reset: Gotek led turns back on

• 1 Minute and 33 Seconds after reset: Desktop (with Disk Drive A and B symbols) finally appears, Gotek led remains on

If i now click Drive A on the desktop, it gives me a Drive A is not responding error.

Sometimes it goes straight to an empty desktop after the first drive A access. When doing this however, it sometimes does 2 or 3 steps in seeminly randoom directions. I tested it with another straight cable and another Gotek, this weird, unreliable flaykyness persists. I now also think that the adapter is probably wrecked.

I had a look at some ebay offers for external st disk drives, but there's not a lot and what I could find was quite expensive.

But this thing caught my eye:

Atari ST STFM STE External Floppy Drive Adapter Gotek

Would you recommend me this product?

It says it will make the gotek show up as drive B on STFs and as drive A on regular STs without an internal drive (like mine)

So, if I understand correctly, when an STF accesses Drive B, it actually selects Drive A on the external connector in order to allow it to use the same unmodified external drives as the regular ST? Is that why it will show up as either Drive A or B depending on wether the ST has an internal drive?

[rubber_jonnie]

So on any STF/M with an internal disk, plugging in an external disk it should have it show up as drive B. I have an external enclosure with a Gotek in place of a floppy and this is how it works, and it's essentially straight through from the 14 pin DIN of the 34 pin of the FDD. It's set as DS0 BTW and the ST uses some funky logic to decide if you are accessing A or B.

If I plug that same drive into my 520ST, it appears as the A: drive. You should also see a B: drive but it is virtual, so you have to put disk B: into drive A: if that makes sense.

So that adapter appears to be what you need, however I can't recommend it as such as I have never used one. The last external FDD cable I needed I wired up myself from the DIN plug over to a 34 pin plug.

I personally think your adapter may be knackered, and if you are happy to buy that replacement adapter from eBay then it would at least mean you have ruled out another link in the chain, however if you do buy it, then that is entirely your choice, as it's not fair for me to recommend something I've never used.

[ijor]

...
If i now click Drive A on the desktop, it gives me a Drive A is not responding error.

Do you have valid images on the Gotek? Can you use the Gotek buttons to switch among the images?

I now also think that the adapter is probably wrecked.

It could be the adapter. But honestly, it could be anything. It could be the Gotek, and it could also be the computer.

I was more worried about me not seeing them on the scope's screen as they happen, as the scope can only display a signal live, the trigger is only used to "sync" the signal. (at least I think so)

It might be very difficult to diagnose without a proper instrument.

So, if I understand correctly, when an STF accesses Drive B, it actually selects Drive A on the external connector in order to allow it to use the same unmodified external drives as the regular ST? Is that why it will show up as either Drive A or B depending on wether the ST has an internal drive?

Check the ST and the STF schematics and you would understand. But in essence yes. On STF models with internal drive, the computer DS1 output is connected to the external drive DS0 pin.

Note that in addition there is a high level logical mapping performed by the OS when you have a single drive.

[russellnash]

Here is a source of external floppy adapters in case you need it.

[LarryL]

looking at the photos 133134, 133209 and 133218 I am not sure, if the solder jumpers at the adapter are set right - if they are set at all???

[rubber_jonnie]

looking at the photos 133134, 133209 and 133218 I am not sure, if the solder jumpers at the adapter are set right - if they are set at all???

This is partly why I believe the adapter is faulty.