Scan Doubler with Angus Generated Tick - Scrolling Picture

Hi there,

So I am a super happy ZZ9000 user. Best. RTG. Card. Evar!

I am building a new A2000 rig and this will have a PC/ATX PSU which means it is missing the necessary tick signal. For this, the usual approach is to switch J300 on the motherboard to “Angus Generated Tick”. This works for my RPI base scandoubler but not for the ZZ9000. What I see is a picture which scrolls rapidly. I have the impression that it is showa 50Hz screen to 60Hz without taking into account the difference in frequency. I have made a video of this to show what I mean:

I have two rev 6 Amiga 2000 motherboards and the effect is the same on both. If I connect an original A2000 PSU and use the tick generated from the PSU, it works correctly.

Is there something I forgot to set or something I could be doing wrong?

Many thanks,

Ronnie Beck

  • Amiga model: A2000
  • 680x0 CPU: 68080/68000
  • RAM Configuration: 1 Mb CHIP/128Mb Fast
  • Kickstart, AmigaOS Versions: OS3.1
  • ZZ9000 Firmware version: 1.8
  • ZZ9000 Driver version: N/A (problem observable in early boot menu)
  • Monitor model: Various Samsung monitors
  • Other Zorro cards: None

In case you didn’t see the other post I will write again for clarity that I have an R2 board and the fix (drilling the hole at the specified place) has been done and the voltage is correct.

I’d like to chime in on this. I am having a similar issue. I can get the screen to display but its not stable and “Flickers” quite a bit. My normal 23pin video is just fine. Everything else works on the Amiga. I cannot switch over to the ZZ9000 card because of the screen issue.
Amiga 2000
A2630 Accelerator w/4MB RAM
1MB Chip / 6MB Fast RAM
3.1.4 ROMS and OS
ZZ9000 Firmware Version 1.8
NEC Multisync
Supra 2400i Modem
PC-AT Power Supply installed / J300 jumper set
ZZ9000 Trace Cut modification has been performed.

Any ideas? Is it the timing tick from the Agnus the problem? Do I need to reinstall a repaired true A2000 power supply?

Ok. My fellow Amigians… I have been troubleshooting my issue and have found something interesting. When I run the ZZ9000 card without the passthrough ribbon cable, the screen is awesome! The minute I plug in the ribbon cable and use the video port pass through, my screen is flakey and flickers.

So, with that in mind. Is there anyone on this forum that has a good understanding of the amiga video circuit? I am going to scope this out and see if I can find the noise. I would bet my money on a bad cap or bad ground somewhere in the video circuit of the A2000.

Please let me know if this helps. I will continue troubleshooting my issue and will post my findings here.