exxos's Atari, Amiga & retro forum

I've posted very similar threads regarding this issue, but I've simplified the issue, so I'm starting a new thread...

I have an Atari Mega ST2 and a MegaFile 60. When the MegaFile 60 is connected to the Mega ST2 it is not seen. I've verified this using various programs included in the ICD drivers. No ACSI ID's are found on the bus.

I also have an Atari 1040 STe. When the MegaFile 60 is connected here the HD boots up and I can use the drive without any issues.

On the Mega ST2 I have done the following mods:
- Swapped the PSU out for a Meanwell unit
- Added the resistor network to my DMA chip - I've checked and it is the correct value and installed properly.
- Added 2 meg of DIP memory to the mainboard
- Using 6 chip TOS 1.04
- Swapped the DMA chip for a known good one from EXXOS... and I've added the resistor network here as well.
- Reflowed the solder on the DMA DB connector

I have not swapped the bus resistor networks yet. I've ordered them and I'm waiting for them to arrive.

What should I be doing to troubleshoot this further?

Side note... I don't have any issues with my floppy drive.

Do you have a spare 1772 you could try swapping ?

exxos wrote: 01 Dec 2021 20:12 Do you have a spare 1772 you could try swapping ?

Thats the WDC chip? No, I don't... and it isn't socketed, making it a double pain to try. :(

Is this chip also used in the STe? I might go to the trouble of installing a socket on the Mega if so.

yeah WD1772 is used in all STs.

I just swapped out the DMA chip for the original, with no resistor network, and no change. Does not detect the MegaFile at all, which should be showing up as ID3. :(

...and for ONE boot of the Mega ST2 I did get a "ID3: Unit not recognized" message (or something similar) from the ICD drivers.

...and one thing more to mention... The activity light on the MegaFile stays on while the Mega ST2 is powered on. It does go off if I reset through C-A-D or the reset button, until the ST starts up again.

It's better to have the resistors network on the DMA as it's known to cause problems. But of course whether or not such modifications solve your actual problem is another story as it could literally be anything.