Atari STE with T0 and e7 spurious interrupt

[exxos]

Ah crap, I measured from the DMA chip for some reason. So IACK does goto the GST. Well its why I shouldn't reply to people in the middle of the night. Its 4am now :lol:

So IACK does seem broken on your machine. But do the IPL pins show all high now anyway ?

[32bitminus]

Ah crap, I measured from the DMA chip for some reason. So IACK does goto the GST. Well its why I shouldn't reply to people in the middle of the night. Its 4am now :lol:

So IACK does seem broken on your machine. But do the IPL pins show all high now anyway ?

Happens to me too :) I want what I paid for this advice refunded :) Next time I am in the UK you can buy me a pint!

I get:

25 IPL2 LOW
26 IPL1 HIGH
27 IPL0 HIGH

Well now I will see if I have a bad VIA or something under the GST, I am curious!

I am not going to solder that chip back in, my rule is socket anything removed, so will have to wait a bit, will dig through my sockets but I don't think I have anything thing that big hence the order.

[32bitminus]

My fancy bodge for pin 83, now tones out to pin 45 on the MFP :)

That was fun... After looking at the photo, I went and bent the wire a little at the curve to take strain off the package's leg/solder pad mechanical connection. It's perfectly horizontal now, so no one follow my example ;)

Needs a little hot snot to hold it in place.

Now x my fingers I didn't damage anything removing the MFP!

signal-2022-12-10-004749.jpeg

[32bitminus]

Ok, this is like a TV show with a cliff hanger for me.

I couldn't wait and its against my OCD to use my cheap 24 pin sockets, but after toning out all the VIAs, I installed two 24 pin crappy cheap sockets, cleaned up the 68901 pins to be solder free and smooth as possible.

Installed and...

signal-2022-12-11-110328.jpeg

It freakin works!

So pretty sure all the rework was who knows what and I just had a corroded Interrupt Acknowledge line.

I know near the end of both Commodore and Atari people complained the quality went down, but considering all the heat I applied to this board, it has held up OK.

I think this one may be a victim of uncontrolled storage as the plating on the jaguar ports was a bit rough, i.e. humidity corrosion. So maybe some bad solder masking go to this computer.

Will run a full test suite with the cart next.

Exxos thanks for your help, I started this on another board and moved this problem here and you were way more helpful, will always support your store for my retro Atari stuff!

Next on to the Amiga 600 mobo you may notice in the photo, the caps have just started to leak...

[exxos]

Well done !


:bravo: :2k2:

[32bitminus]

Without the harness, does this seem normal?

signal-2022-12-11-120105.jpeg

[32bitminus]

Ok, before I get too happy, I noticed no A/B or Trash Icons, looks like I have the TOS 1.62.

I plugged in the floppy drive, and power. When turning on the machine, I see the drive access light come on, then off.

If I stick a floppy in it spins for a few seconds, so it gets power.

Perhaps this is why it looks like the WDC1772 Chip was replaced before :)

I assume this is a common issue, any thoughts on what to search?

[exxos]

Generally it would be corrupt newdesk.inf file on the drive. If you get to desktop in that state without even a floppy in the drive ( or a blank floppy) then I don't know why you would lose all three icons.Maybe the ROM is corrupted. Afraid I don't know.

[Badwolf]

Quick test in Hatari shows that TOS1.62 will boot to an empty desktop if no drives are found, so despite the drive responding, the ST isn't seeing it.

You woudn't happen to have an external floppy drive?

BW

[32bitminus]

Ah great test pattern, I didn't think of using emulation for expected behaviour.

I have an external drive, just no PSU :)

I did a few more tests, it looks like its not able to do a seek to track 0, so could be mechanical or electrical.