Floppy Stops working with megafile connected.

[AtariFox]

Message me on here or on my website if you like

I went and messaged you.

[AtariFox]

Old bump. I finally got around to having time to play with my atari again.
Everything is fine with it since steve did his magnificent repair on it.

But I'm still having the same issue even with all the fixes applied.

The floppy drive stops working when i plug the megafile in ( this means i can't load any ICD or drivers). The cables.. been sheered in half at one point.. SO i was hoping anyone has a spare db 19? cable? I could attempt to try to fix this one though.

However i'm still not sure whats causing it. So i'll have a go at remaking/repairing the cable first.

[exxos]

Does the megafile work on a different ST ? Maybe the megafile is just faulty... ?

[stephen_usher]

I had the same with the STFM I've been working on to fit the TF536, but with an UltraSATAN rather than Megafile.

Changing the motherboard pull-ups to 4.7K helped a little (2.2K pull-ups stopped the floppy working even without anything on the ACSI). The biggest change happened when I swapped out the DMA chip. I think the chips must just get tired.

The ACSI port could really do with being fully buffered and maybe opto-isolated for safety.

[AtariFox]

Does the megafile work on a different ST ? Maybe the megafile is just faulty... ?

Unfortunately, I do not know if it is. I don't have another atari to test it with.

I had the same with the STFM I've been working on to fit the TF536, but with an UltraSATAN rather than Megafile.

Changing the motherboard pull-ups to 4.7K helped a little (2.2K pull-ups stopped the floppy working even without anything on the ACSI). The biggest change happened when I swapped out the DMA chip. I think the chips must just get tired.

The ACSI port could really do with being fully buffered and maybe opto-isolated for safety.

My STFM has had all the mods and fixes done to it by one of the forum users here. All chips and entire data bus resistors done including a new DMA. Steve' should have it all on his repair blog for me.

I'm not sure what you mean by the ASCI port being fully buffered. I'm kinda thinking theres a short of the repaired cable. (i didn't repair it)

I'll have to make a new cable I suppose. Unless there's a diagram of what coloured wire is what.

[exxos]

Cannot remember if its been tried, but have you swapped the 1772 for a different chip ?

[Steve]

He has had a brand new 1772 from your store afaik Chris. He's also had 100% of all mandatory fixes done.

[exxos]

He has had a brand new 1772 from your store afaik Chris. He's also had 100% of all mandatory fixes done.

Was this a ST or STE ?

It might need buffering.. which is only on the STE...

[Steve]

STFM

[stephen_usher]

I'm not sure what you mean by the ASCI port being fully buffered.

Basically, it means that there's a component which takes the input from one side and then retransmits the value to the output side with no direct electrical connection between the two. It means that any incorrect (low or high) voltages are not transmitted to the sensitive components inside the computer.

With optical isolation this takes it a step further protecting against static discharge or a large DC bias.

On the ST the ACSI port is directly connected to the DMA chip.