520ST fully working and upgraded
Posted: 01 Feb 2020 16:47
A while ago, I got a 520ST from exxos, knowing full well it wasn't quite right, and prepared to have a go at bringing it back to life. It seemed the right thing to do, because cosmetically it was in very good order.
So first off I resolved the problem of no PSU by building one (viewtopic.php?f=9&t=1714&hilit=PSU), then resolved the problems with RAM. There was track damage due to a piggyback expansion, and in the end I felt it was simpler to remove all the RAM and fit a SIMM adapter to the MMU and Shifter, so having done that the machine was finally booting to desktop.
That left two problems:
1. The floppy drive didn't work,and any attempt to access a disk crashed the machine.
2. The TOS was version 1.00.
I'm happy to say the day is finally here where there are no problems left :)
I thought I'd tackle the FDD problem first, since I knew the machine was working upto getting a desktop.
That's where the diag cart came in, and on running a floppy test, this was the result:
Having already tried swapping the DMA, FDC and YM chips for known good items, they were ruled out, leaving the GLUE and MMU. Since the MMU had a memory adaptor plugged in, it had to be GLUE first, and lo and behold, with a replacement GLUE installed, the FDD sprang back into life :) I'll test the GLUE on another machine, but it certainly looks like it's had it's day.
The TOS upgrade was simple. I sourced some PROMS from evilbay, and split a TOS 1.04 image using ROMSPLIT on Hatari to get the 6 ROM images I needed and burned them.
Once swapped out,everything worked like a charm.
And I'm very happy to have this lovely machine back in the land of the living. I'll get it back in the case, hopefully tomorrow, but I think I'd better have a dig for some 1MB SIMMs and see how it likes 4MB first :)
I guess it might also be worthwhile seeing how it likes SMonson's DVI adapter whilst the lids off too.
So first off I resolved the problem of no PSU by building one (viewtopic.php?f=9&t=1714&hilit=PSU), then resolved the problems with RAM. There was track damage due to a piggyback expansion, and in the end I felt it was simpler to remove all the RAM and fit a SIMM adapter to the MMU and Shifter, so having done that the machine was finally booting to desktop.
That left two problems:
1. The floppy drive didn't work,and any attempt to access a disk crashed the machine.
2. The TOS was version 1.00.
I'm happy to say the day is finally here where there are no problems left :)
I thought I'd tackle the FDD problem first, since I knew the machine was working upto getting a desktop.
That's where the diag cart came in, and on running a floppy test, this was the result:
- Diags.jpg (89.82 KiB) Viewed 4241 times
Having already tried swapping the DMA, FDC and YM chips for known good items, they were ruled out, leaving the GLUE and MMU. Since the MMU had a memory adaptor plugged in, it had to be GLUE first, and lo and behold, with a replacement GLUE installed, the FDD sprang back into life :) I'll test the GLUE on another machine, but it certainly looks like it's had it's day.
- Success.jpg (63.15 KiB) Viewed 4241 times
The TOS upgrade was simple. I sourced some PROMS from evilbay, and split a TOS 1.04 image using ROMSPLIT on Hatari to get the 6 ROM images I needed and burned them.
Once swapped out,everything worked like a charm.
- Working.jpg (116.75 KiB) Viewed 4241 times
And I'm very happy to have this lovely machine back in the land of the living. I'll get it back in the case, hopefully tomorrow, but I think I'd better have a dig for some 1MB SIMMs and see how it likes 4MB first :)
I guess it might also be worthwhile seeing how it likes SMonson's DVI adapter whilst the lids off too.