JPN Saturn "repairs" my CRT

[davyk]

I have a CRT rigged up to several consoles via a powered Thor SCART switch.

My CRT used to make a high pitched sound accompanied by slight interference on the image. It would get worse when there was a lot of white displayed (and less noticeable when the screen was darker). It used to happen when the screen was cold and would sometime stop once the set warmed up.

When I got the powered SCART switch and JP Saturn the problem seemed to go away - it is as if the Saturn signal resolved whatever issue there was.


Wind forward a few years and recently I have been using the CRT a lot more now that my game room is more or less setup as a I like it and I've playing other consoles on the CRT such as my modded Megadrive and some Gamecube and Dreamcast stuff. The issue returned  - I suspect it might have been caused by running experimental ROMs on my atari 2600 for the homebrew programmers at atariage.com........I have a Harmony cart that lets you load ROMS off an SD card and homebrew devs have recently been asking owners to load up some ROMs to report results - these seem to be pushing the Atari hardware to its limits and they display numbers that the devs use to work out the maximum displayable area they can work with across a range of CRTs.

Anyhow - after this (can't be sure - but pretty sure it was after this) the old problem returned - the CRT makes a high pitched noise and slight interference on the image. As soon as I used my JPN Saturn again the issue went away after a minute or two. Very odd indeed.

Has anyone, particularly in the PAL region , ever experience any issues like this?

[HennessySlick]

I find that I get a loud hum when certain colours are being displayed through cheap SCART cables - could that be the problem?

Do you have PAL Saturn to test this with? Could just be that other things you've been using have poorer quality SCART cables.

[davyk]

I think the PAL Saturn may have contributed to it as I was using that prior to the problem arising again too - but truthfully  - I  think the 2600 experimental ROMs are the culprit. It's just funny that the JP Saturn seems to have sorted it out though! I have changed my SCART cable recently but it was several weeks before the issue started (the cable was £20 in Maplins so it is half decent). I suppose it could be quality of the SCART cables running from the console to the switch.

I've used this set rotated quite a bit too and thought that might have been the cause but I've had it sitting in normal hori position for a few months now with no issues.

Will check again the evening but hopefully the issue is resolved as this particular set has a lovely warm image and it doesn't have any image centering issues that other CRTs I have owned in the past have had.

[zyrobs]

If you get buzzing noise when the picture gets brighter with a SCART cable, then the fault is in the cable not having proper shielding (the video signal increases as the video gets brighter, which translates to increased humming as it bleeds into the audio).

[davyk]

Hmmmmmm..... what would make it go away though? It has stopped happening with no changes made to the setup. It went way for a couple of years and then came back for a week or two.

I wouldn't call it a buzz - like a high pitched screeching sound - not very loud - just very high pitched. Gets louder with brighter images. Very odd.

I'll need to keep close eye on what I'm doing to see if I can figure out what is causing it to re-occur.

[zyrobs]

Mar 17, 2017 22:30:41 GMT davyk said:

I wouldn't call it a buzz - like a high pitched screeching sound - not very loud - just very high pitched. Gets louder with brighter images. Very odd.

That's exactly what the interference sounds like. It happens on all SCART cables too (not just for the Saturn), except the very expensive, thick, super high quality ones.

Your choices are either
- use composite video, RGB won't interfere with those.
- get a different SCART cable, hope it has better shielding (the highest quality SEGA cables still have some buzzing, but it's faint enough that you can only hear it if you crank up the volume)
- solder your own SCART connector with higher quality cables inside, you can buy the 10-pin mini-din end on ebay
- do an optical audio mod - eliminates all noise since you are getting digital audio straight from the sound chip.

[davyk]

Interesting. I'll look into that. Many thanks.

I was afraid that I was going to have to look for another CRT and they are getting harder to find where I live.....

[davyk]

zyrobs - can you recommend a cable supplier for my JPN Saturn?

This effect started again. When I unplug the Saturn cable from my powered SCART switch box it stops so I think your are dead right about the cable I have and its lack of shielding. I have noticed my Dreamcast does it too but only slightly - I'm surprised at that because it's an official one.

[zyrobs]

I use the cables made by thefoo.83 on ebay, but I notice that they've been selling slightly different ones since I last bought - they add a small box to split the composite signal to c-sync. I dunno if they still use the same shielding or not, but it's fairly cheap so it's worth a try.

[davyk]

Thanks for the tip!

Ordered one. Works with PAL or NTSC - have separate cables at present (have an official PAL cable and got the JP one off an eBay seller that I can't remember the name of) The cables have served me well up to now but this interference definitely seems to be coming from cables somewhere. I'll need to start labelling them!

Now that I've unplugged everything I'm still getting it - even with my Gamecube now!

I'm wondering if all the power cables and AV cables need tidying up - is there a chance there is interference there? When I power up to play a game the way I have everything connected all consoles get power even though they are switched off. And maybe all those sphagetti cables that are tangled up are maybe causing a problem?

Think I need to strip everything out and add in one console at a time to see when it starts again - that might identify the culprit.

[zyrobs]

Maybe the cable you have between the switch and the TV is causing it...?

[davyk]

Possibly. It's a 3M SCART lead but it's of decent quality and has quite a thick and heavy cable.

I might have to connect the consoles directly to eliminate that. Though the thing is I can go for months with no interference and then it pops up again. I think if it was that cable it would happen all the time. It is pretty weird. It might be the SCART switch - it's a nice powered 5 into 1 Thor switch that you can't get any more.

www.videogameperfection.com/2014/06/29/control-10028570t-review/

[zyrobs]

Jul 7, 2017 20:36:20 GMT davyk said:

When I power up to play a game the way I have everything connected all consoles get power even though they are switched off.

The SCART cables carry power, so it is not impossible for either the console or the switch to try powering the rest of the units, if the switch is not made properly. Some of the power might bleed back through the port into the consoles. It should be easy enough to measure with a multimeter.

[davyk]

Yeah. I have noticed the GC power indicator coming on occasionally - so perhaps the switch has an intermittent fault.

[davyk]

Starting to think it's the TV now.

Have connected different consoles up directly and still getting this. Have tried via SCART (MD , Saturn), s-video (SNES) and even RF (2600) and get it no matter what. It will probably go away itself and then come back after several months- that's been the pattern.

Will need to start actively looking for a replacement I think. Hard to find where I live though