Prismatic Ray stability issue


i am experiencing some trouble with my Prismatic Ray:
I can’t set it to a slow and smooth vertical scrolling speed. It keeps changing the scroll direction and the bars are bouncing. The bouncing also happens when it’s synced.
I tested it with different PSUs, different power cables, sync via rear RCA and via front panel sync input (both from Visual Cortex rear RCA sync/front minijack V sync) and no sync at all.
The problem still stays the same.

here are some examples I filmed off the screen:

Does it need a repair or is there anything I can do about it?

Thanks :slight_smile:

Thanks for sharing. Does the jittery “bouncing” occur with both H & V sync? What are the specs of the power supplies you’ve used? Have you tried just isolating Cortex and Ray on a single PSU?

The bouncing does not occur with H sync.
I also have to point out that the bouncing varies, sometimes it’s harsher or looks just different than other times. On a few sessions i thought it was gone, but the next time it would be back.

I didn’t try isolating VC and PR, i’ll do that tomorrow.

PSU in my main case is the ACL Lo Noize, actually very high quality and does what the name says.
Specs from the web:

  • Switching power supply, developed especially for modular systems.
    • +12 V – Regulated, filtered, less than 2 mV fluctuations and noise at full capacity, typically 0.5 mV.
    • -12 V – Regulated, filtered, less than 2 mV fluctuations and noise at full capacity, typically 0.5 mV.
    • +5 V – Unregulated, filtered, less than 30 mV fluctuations and noise. Less than 10 mV at full capacity.
  • Overvoltage and short-circuit protection.
  • Primary voltage: 100 – 240 V
  • Maximum continuous power:
  • 2 A at +12 V
  • 2 A at -12 V
  • 4 A at +5 V

the other PSU is a cheaper one from Arturia:

  • Up to 1600mA on +12V and 1600mA on -12V (2 separate circuits of 800mA)
  • Up to 900mA on 5V (USB + 5V modules)
  • Power rail with
    • Noise filtering
    • 20 standard power slots with up to 800mA on +12V and -12V

Thank you so far :slight_smile:

I also have two prismatic rays that won’t slow scroll. They temporarily sync for periods of less than one second.
Both my units that do this are rear RCA sync and my older v1 with 14pin does not.

Is that only when vertically synced?

Diver may be the best option for slow scrolling.

isolating PR and VC on the same PSU didn’t change the issue…
reading nicks answer, can I conclude that this is a common behavior?
I can live with it, but of course occasionally it would be nice to have it scroll smooth and slow.

It is odd that it won’t scroll when sync is disconnected.
Let’s see if more people with late-revision PR’s can weigh in with their experiences. This isn’t an issue I was aware of.

Yeah, I also thought it to be a sync issue.
Just to be clear again, it does scroll without sync, but not in a smooth and slow fashion.
I tried it again today, but having sync connected or not still didn’t make a difference.

I have trouble with my RCA Prismatic Ray acting bouncy, both in unsynced and synced scenarios. RCA sync ended up being pretty much unusable. I currently only sync it via front panel from Visual Cortex and it’s better than rear sync but still slightly problematic. Other non-video VCOs sync fine to VC’s V sync out so it seems as if the problem lies in Prismatic Ray. I have two that act this way and I’ve tried numerous sync chains with no luck, and the problem has persisted between two different eurorack cases/PSUs