MiSTer FPGA Forum

Hello !

I have a 1084 Commodore monitor that make noise when changing core,
When I change a core I can hear some like "shhhh shhhhh"
When the core is loaded, the noise disappear.

I also have another 1084, and one 1081 Commodore monitor , that makes the same noise.
My other CRT's (monitor or TV's) works normally.

So it has to be something with this commodore monitors model.

Is any dangerous ?
if you are an user of Commodore monitors: do you hear the same noises?

thanks for the help & info,

I may be able to help you with this. I have several Commodore monitors. I have yet to hook them up to a Mister though. How are you connecting yours? Are you using a luma / chroma to S-video adapter, and then some HDMI to S-video adapter or a newfangled adapter from the IO board to S-Video?

I'd love someone to make a commercial adapter for direct MiSTer-to-RGBi connection to use some monitors in their full RGB capability.

If you provide more information as to your connection setup, I can try to replicate it.

This is normal, the audio amplifier picks up so much interference in this monitor. It’s cheaply and poorly constructed.

You may use an external amp and speakers for better sound.

Hello , Thanks for all your replies !

I forgot to comment that I use a PAL monitor, with RGB-SCART , directly from Mister, as I do with my other CRT displays

I understand that is normal then, as the user C-R-T said in their message , and it's due the amplifier

If it is coming from the speaker(s) and you are using the analog audio output of an analog IO board with your MiSTer, that output is known to be really noisy.

Hello again,
I have tested another time, and the sound doesn't seems to come from the speakers.

If I test with Mister without SD CARD, it sounds ("sssshhhhhhhh") all the time. No differences if I manipulate the speakers control.

I have tested also with the volume of the integrated speakers at minimum , (when I start mister sound; and then stops when Menu core is loaded ; and again comes when I load other core, and stops when the core is loaded)

I have tested also with external speakers. The sames sound.

So I think it has to be some electronic sound of a component (as it comes from inside the monitor) when changing screen mode , or resolution or something (bad knowledge of electronics, sorry).
Only happens with my Commodore monitors, On others CRTs all is OK.

Are you sure you are not just hearing the high frequency noise generated by your flyback transformer inside the monitor?

Xbytez wrote: ↑Fri Aug 19, 2022 8:05 pm Are you sure you are not just hearing the high frequency noise generated by your flyback transformer inside the monitor?

I think that it could be the answer ... !
perhaps the flyback on that models (1084, 1081) makes that noise in certain situations.

It might be because of no sync signal or an incorrect frequency signal being sent. I'm not sure if MiSTer never sends more than 15Khz to the VGA output while changing cores. I remember some work being done on that quite a while ago. I vaguely remember a 15Khz only option for the ini file, but can't find any information about it anymore.

I'm also wondering if you can try a simple replacement speaker(s) and do a quick desolder/resolder to test? It is true that the flyback may be noisy.
I have many CRTs and what younger folk call "The CRT sound" of which my whole life was just "tv" can vary from set to set. Geez, by calling a tv a 'set' I just just felt old like my dad calling a 'copy' from a photocopier a 'photo-STAT' copy.