SNES Intermittent Buzzing

[flex]

Hi Guys,

Whilst playing some Super Mario Land 2 via a Super Gameboy adapter on my SNES I started to hear some horrible buzzing noise coming in and out completely swamping the audio. This doesn't sound like the usual buzzing noise you get with poorly grounded SCART cables etc as I am using a high quality shielded RGB cable. I have since tested a normal cartridge etc and the noise is still there, however it seems to have calmed down a bit and you can mainly hear it when first turning on the console for a couple of seconds or the old little pop etc. I am using an original nintendo AC power supply (with the blue connector) and swapped this for the one that goes into my NES (also an original AC power supply) and it does the same.

My Console is also modded with a SuperCIC and UIGR.

Would I be correct in thinking this is probably a capacitor issue or something else?

[flex]

For anyone interested I took apart the console and noticed it looked really dusty and dirty under the heatsink area at the back.. i believe this is where the audio chips live as well. I have noticed some areas with some dodgy looking traces (black marks around c59 / c60 area). I cleaned up the whole area with some isopropanol alcohol and got rid of all the dust etc and the issue has not come back.

I took a picture of the board anyway.

Any idea if those black marks look suspect or not?

https://photos.app.goo.gl/be6EurTA7y2XGBuC7

[borti4938]

You definitely have to replace C59 with a bi-polar electrolytic cap (10uF/25V). The polarized version is a design issue in SNSP-CPU-01.

[flex]

You definitely have to replace C59 with a bi-polar electrolytic cap (10uF/25V). The polarized version is a design issue in SNSP-CPU-01.

Cheers Borti! will do that.

[flex]

Even though the issue never returned I finally got round to recapping my SNES fully, there were definitely a number of leaky caps.... had a bit of a moment when the pad lifted for C65 but consulted the PAL SNES schematic and got around it with a bodge wire from the negative leg of C65 to pin 12 of the Multi AV out (seems to have done the trick).

All seems good, although I would say there is still the issue of some background buzzing when there is white / bright colours on screen, I know this can be caused by cheap SCART cables but i am using a decent shielded cable from retrogamingcables.co.uk but the noise is still there.

I know this is an early revision SNES so perhaps it is just the way it is with this model.

[Makinx]

Their cable quality varies. I have an older cable from them which has the audio buzzing, and a newer one I bought last year which doesn't. I haven't had audio noise issues with any of their newer cables, although 1 cable I bought did have one audio channel that didn't work at all.

[flex]

Their cable quality varies. I have an older cable from them which has the audio buzzing, and a newer one I bought last year which doesn't. I haven't had audio noise issues with any of their newer cables, although 1 cable I bought did have one audio channel that didn't work at all.

Ah ok that is good to know... i have noticed they no longer list this cable for sale on their site, (It was a PAL sync on luma cable). I might treat myself to a packapunch cable if I am feeling flush otherwise I guess I will just live with it

[ASDR]

Ah ok that is good to know... i have noticed they no longer list this cable for sale on their site, (It was a PAL sync on luma cable). I might treat myself to a packapunch cable if I am feeling flush otherwise I guess I will just live with it

Just wanted to chime in to say that the non-fully shielded (non packapunch) version definitively has some chirping/whine with the SNES, even on a csync cable. It's especially noticeable on high-frequency content, try the grids from the 240p testsuite if you really want to hear your SNES sing. The fully shielded version does not show this behavior in my setup. It seems that generally buying the fully shielded is worth the price, even if spending hundreds on fancy cables does make me feel like some audiophile nutjob.

[flex]

OK so.... I have been a little but stupid here.

I figured what the hell and bought a packapunch cable to discover it sounded exactly the same..... I started playing about and plugged the cable directly into the TV instead of going via the SCART switcher box and whaddya know... quiet as a mouse! It is a decent scart switch which is well isolated but what I forgot to check was that the cable going from the switch to the TV is well shielded as well! DOH!!!

I think a better cable from the switch to the TV that is all that is required here really. It is funny because the issue only really becomes noticeable with the SNES and not the other consoles, I guess the SNES is just more susceptible to it.