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.

[SailorSat]

I know that problem myself.
I think it has to do with some kind of short between HSync and VSync pins (at least that was the problem for me).

[Toni Wilen]

Originally Posted by mingle

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

Repeat booting is guaranteed caused by genlock detection (without real genlock connected).

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

Probably something to do with component tolerances on H/V sync lines.

Here are some simple sync line hacks (without need for buffer chip): http://eab.abime.net/showthread.php?t=46172

[Info-Seeker]

would a sync strainer help with this issue?

[rkauer]

Yup.