A1000 boot trouble

[Aeberbach]

Hi all, I got a nice A1000 in trade for some other machines I was not using. I am very happy to have it as I have been looking for one of these for many years, it was my first computer. Everything is in great condition, not even dust on the PCB.

The machine powers on and the left LED flashes normally. I don't hear the short tone sequence that I think I should hear though an amplifier is connected to the phono jacks. After a brief pause the kickstart graphic is displayed. When a kickstart disk (I have tried four of them, also took out the FDD and tried loading from Gotek, same) is put into the drive it loads, the disk steps about 24 times, then the screen goes grey again before disappearing - nothing happens after that.



So far I have checked power supply voltages, 5V and 12V look fine. None of the electrolytic capacitors look at all fat, there is no evidence of any work even done to the board. I have removed all of the socketed ICs and reseated, ,though they looked clean. I have swapped the two 8250 CIAs but that made no difference. Removed 256k RAM expander, no change. The guy I got it from claims it was working just a few days ago... any idea where to begin troubleshooting?

[Hellraiseruk]

Hi,

You say you've tried 4 disks and a Gotek, are they all built from the same image? Could be the kickstart image you have is corrupt?

JD

[Aeberbach]

No, tried a few different images on the gotek and a few different floppies from the disk box.

[Hellraiseruk]

Wonder if it's some kind of RAM issue, as it executes the code from the boot rom, but then fails to run kickstart which would be loaded into RAM. Not that familiar with the a1000, but pretty sure there is a version of Diagrom you can use with it, might be worth investigating.

JD

[Aeberbach]

How annoying, I have 27C64 and 27C512 but no 27C256.Might be easier to swap RAM than get some as I have lots of 41464-15.

[lilwashu]

Are you using an RGB to VGA adapter in the rgb port by any chance?

[Aeberbach]

15kHz LCD display from the 23-pin video port, yes. I suspected that maybe the display wasn't as compatible as claimed (though it has been working in every output on the A1200) but popping out the kickstart disk and putting a workbench disk in did nothing.

[Aeberbach]

The solution is... the video cable! David Dunklee (Parceiro creator) suggested removing the DB23 as a cable that is improperly wired can stop the A1000 from booting. Sure enough, with the yellow composite video connected:

IMG_3472.jpeg (80.18 KiB) Viewed 293 times

And now I have a working A1000, and will soon have a Parceiro II+. Happy day.

[Maximilian]

Thanks for sharing!
I have two A1000 machines here to fix up and this could potentially save me a lot of time!

And good to hear that you got it to work again

[Hellraiseruk]

The solution is... the video cable! David Dunklee (Parceiro creator) suggested removing the DB23 as a cable that is improperly wired can stop the A1000 from booting. Sure enough, with the yellow composite video connected:

Good to hear you got it working, I do dislike faults of that nature as they make no sense when troubleshooting. Good to see you got it all working again though!

JD