Some Amigas won't boot with Multisync monitor connected?

[mingle]

Hi all,

This is a sightly perplexing one...

I have an NEC Multisync II monitor, which I used  for many years with my KS1.2 & 1.3 Amiga 500s and also on an A2000HD (KS1.3) and A1200 KS3.0 & 3.1, without any issues...

I recently tried using it on an A1000 (KS1.3), A3000D (KS3.1) and A4000D (KS3.1) and the machines won't boot fully when the monitor is connected (doesn't matter if the monitor is switched on or not) - they start, but then seems to get stuck in a reboot-loop, until I unplug the cable from the monitor.

Then they will boot to an error screen - at this point I can plug the monitor cable in and I see a guru screen, with the error code 8000000 for task 07003278. After which, they boot and work fine. It's only the initial boot stage that fails with the monitor connected.

I have heard something about needing a buffer on the h & v sync lines and some genlock detection issues.

But, why does this only affect the A1000, 3000 & 4000 and not the others?

I know it's not a hardware problem with the monitor, as I've tried another couple of NECs and they all do the same...

I'd be very curious to know if anyone has a technical explanation!

Cheers,

Mike.

[XDelusion]

Did you have the monitor hooked up to a Windows machine before hand? That might have something to do with it. (joking).

I have not got a clue, sounds like an electrical issue, but I don't know why the video port of the rebooting Amiga's would be any different than the ports on your working ones.

[bbond007]

I bet the monitor is drawing too much power from the computer for whatever reason.

Check whatever adapters you are using. Maybe you have a bad 23pin adapter.

[Gulliver]

Have you considered using Blizkick with the BK module named RebootFix (it fixes a problem with multisync reboot)?

[KThunder]

if you have a diy adapter that is probably the problem. there has to be a buffer chip on some of the pins or the denise? chip will think it is hooked to a genlock and will not initialize properly.

there are several adapters on aminet that have the chip properly setup. a simple straight through adapter is simpler but it wont work.

i had an nec 3d multisync with the original commodore adapter and it worked perfectly.

Different revisions of the chips act slightly differently with some devices.

[Piru]

My guess is that there is a slight potential difference between the ground signals. A500/A2000/A1200 might be more tolerant for it, while the other machines are not. Also if it's close to the border condition (the issue causing problems or not) it can happen that the problem goes away and reappears by just changing the configuration slightly. This may lead to puzzling results if you try to identify the problem by eliminating or swapping the HW for instance.

Are you using grounded sockets for both the amiga and the monitor? Are the grounds in the same potential (that is: are the plugs connected to the same ground)?