exxos's Atari, Amiga & retro forum

exxos wrote: 01 Oct 2021 11:47 I suspect you may have a grounding problem. It is why I suggested making sure you use the same power point for all items. The only way to really prove this would be to run the OSSC and Atari on battery to isolate it from the mains GND.. Simple if you have a "portable" UPSU I guess..

The Atari and OSSC were plugged into the same power bar. I will have a play and see if I can improve it with my spare data centre power bar.

I had the same issue with an OSSC and a ZX Spectrum (using a Harlequin) some time ago. Literally the exact same picture at what you had posted in the first post with those dots.

I had the OSSC connected to a SCART switcher by Lotharek. I also had an Amiga and a few other machines connected to the same switch. But, oddly, only the Speccy produced a display with the dots. I totally thought this was an issue with the Harlequin board.

But, then I noticed it was not consistent. One day, it looked fine. Another day, the dots. I shuffled around power supplies and wall power and it seems to have disappeared. I suspect a ground loop problem as others have mentioned.

I've just replaced several power bars with a single data centre compatible unit, so will have a play round see if I can improve it.

But, I think it's likely to be the TV since the interference goes when I unplug the HDMI cable.

I've just pulled some other HDMI cables out of storage too, so will have a play there.

I introduced a new scenario over the weekend as I am adding in a Retrotink to the mix so any of my composite devices can go out to HDMI also.

The set up is this:

Retrotink and OSSC are both connected to an HDMI switch and a single cable goes out to the TV.

I had my QL connected to the Retrotink and the OSSC switched off and could see the interference on the QLs output, so unplugged the power from the OSSC and the dot's disappeared.

I tried moving the OSSC PSU to different sockets, but no change, so it's looking like the OSSC PSU is definitely the the culprit.

Thanks for everybody's input, I just need to try and find a PSU that isn't causing the interference, which is annoying because the PSU was new with the OSSC, and as I've had it over a year it's probably too late to send it back.

So, it seems that I've found the solution to my OSSC problem.

Turns out it was the PSU all along. I swapped over to the PSU for the one from the Retrotink and all interference disappeared. I'm sure I already did this, but it's possible I just went "It's new, it can't be that".

Anyway, I found another PSU swapped it in and it's all good. Very strange, but glad it's gone.

rubber_jonnie wrote: 08 Dec 2022 14:59 So, it seems that I've found the solution to my OSSC problem.

Turns out it was the PSU all along. I swapped over to the PSU for the one from the Retrotink and all interference disappeared. I'm sure I already did this, but it's possible I just went "It's new, it can't be that".

Anyway, I found another PSU swapped it in and it's all good. Very strange, but glad it's gone.

It's always the PSU. ;-)

stephen_usher wrote: 08 Dec 2022 15:16

rubber_jonnie wrote: 08 Dec 2022 14:59 So, it seems that I've found the solution to my OSSC problem.

Turns out it was the PSU all along. I swapped over to the PSU for the one from the Retrotink and all interference disappeared. I'm sure I already did this, but it's possible I just went "It's new, it can't be that".

Anyway, I found another PSU swapped it in and it's all good. Very strange, but glad it's gone.

It's always the PSU. ;-)

Yeah, bloody cheap ass thing :(

I'm about to start tidying up all my wiring, so figured it was a good time to do it.