Monitor interference on New Net City

[BuddyC]

After putting my second NNC in tate, I noticed something stra with certain PCB’s.
Anything 31khz and all CAVE CV1000 PCB’s looks excellent with no interference and a rock solid image using @invzim excellent jammafier.

When using Psikyo PS3-V1 (Strikers 1945 II) or CAVE 68000 PCB’s (ESP Ra.De. & Guwange) I get light wavy vertical lines across the image. Not enough to ruin the game, but definitely annoying….

Since it looked like some kind of ground interference, I started to remove power from components that could be the culprit.
After I removed power from the PSU fan…. Voila! Interference gone and everything looking good again.

I installed a Noctua NF-A8 FLX fan in my SUN PSU when I got my cab, but it still caused interference on some games.

Anyone experienced anything similar before? Is the PSU really necessary for home use?

 

[invzim]

PSU fan is definitely needed, I ran mine for some time without a proper fan (inadvertently wired it wrong), and it overheated after a while.

What would be interesting to know is if the interference is airborne or transmitted by wire..

Since you're in full-on OCD mode, you could try disconnecting audio, yes it's a little odd - but I believe the audio amp on the NNC/Naomi cabs is where earth and 0V gnd is bridged together.

 

[nem]

Take the PSU cover off and I think it will be fine in home use, especially if you have the AC fan at the back.

but I believe the audio amp on the NNC/Naomi cabs is where earth and 0V gnd is bridged together.

It's not. Nowhere should Earth and DC ground be bridged together on the cab.

 

[invzim]

It's not. Nowhere should Earth and DC ground be bridged together on the cab.

I haven't checked recently, but seem to remember that the RCA input connectors on the amp is connected to earth, on a game these will be connected to DC GND/0V - and thus you would have a bridge if this is correct.

 

[nem]

They're not bridged.

 

[BuddyC]

Hmmm…. This gets stranger and stranger… While removing the PSU fan out of the equation worked for ESP.ra.de, Strikers 1945 II still has bad interference. After powering the PCB back on, it looked and sounded like the whole chassis (PD2367) was failing… Classic flyback failure on the image…
Got kind of stressed out, but hooked up a CV1000 game and everything worked just fine with nice colors and rock solid image. Let it run for 25 minutes and no issues.

This exact Strikes has been working with no issues and no interference on my other NNC. The only difference is that this has a PD1843 chassis.

weird as hell…

 

[invzim]

They're not bridged.

You are correct, just checked with a multimeter. Earth/GND can be terribly confusing, I may have been thinking about TypeMAME scenarios where I'm pretty sure earth/GND is connected, indirectly connecting cab earth to cab gnd.