I'm going out on a limb here, but I suspect the modern PSU is a switchmode power supply, while the original is AFAIK transformer based. If that is the case, I suppose the switching noise from the PSU might affect the system.

As for a fix, I believe adding capacitors between the PSU and the C-64 should filter out some if not all of the noise. I don't have any more specific knowledge, but I hope that helps anyway.

Hi, what kind of power brick is the new one ?
I'm no C64 expert, even though I was a C64 user as a kid (still have one C64 on the shelf),
but maybe some of the other users can help you better with that information. 😀

General speaking:
According to some of the C64 Wikis the old one was basically a transformer with a LM7805 linear voltage regulator.
These kind of power supplies usually generate no noise (radio interference) and provide a clean DC power.
That's why they were used for a long time in CB and Ham radio. Sadly, they run hot and are not so power-efficient.
The European NES and SNES used 9V AC transformers, too (DC was generated inside of the consoles).

Unfortunately, most PSUs you can buy to today are nolonger transformer-based (there used to be quality ones that were regulated).
They are switched-mode types now. Often produced as cheap as possible in countries that do not care..
As a side effect, they generate an enormous amount of Radio Frequency Interference RFI.

Sadly, things arr unlikely to better soon. Bad switching-circuits caused alot of radio amateurs to give up their hobby.
In Europe, for example, the ban of traditional light bulbs caused an immense increase of LED-based lamps,
which is for itself not a bad thing per se, but they generate RFI. The good ones only little, but they do.
To listen to that noise, all you need is a pocket radio with the AM bands (medium wave or long wave).

https://en.wikipedia.org/wiki/Switched-mode_p … d_disadvantages

PS. Also keep in mind that older power supplies were made with different voltages of the mains in mind.
Back in the 1980s, we had 110V and 220V. Now he have 130v and 250v. Old devices/non-switching PSUs can't cope with that.
Imagine, because of this, the output of an unregulated 9v transformer from the past is nologer ~10-12v but 17v or even more.
On top of that, they are nolonger young. Chances are that they cause some of the device's voltage regulators to operate at their maximum specs.
Edit: Some typos fixed.

This is why I keep the old bricks around, replacing the capacitors on them as needed. A recapped linear supply is basically as good as new (or even a bit better if you upgrade some parts while you're at it) and since we aren't using them as heavily as back in the day neither efficiency nor wear & tear are of great concern. Unfortunately the C64 supply is a huge pain when it comes to repairs because of its epoxy-filled interior.

I don't see the changes in line voltage over time as a big problem either, in most parts of the world mains voltage is specified with a ±10% tolerance, and in fact, it varies quite a bit throughout the day due to grid capacity vs demand, so devices must be able to cope with these fluctuations - and these slightly higher line voltages still fall within tolerance. Besides, most home computer/game console transformers have a 10:1 or 20:1 ratio, so your unregulated output goes up a volt or two at most. An upgrade to slightly beefier regulators and 105ºC rated caps should provide some peace of mind. 😀

I like my electric kettle hot, my incandescent bulbs bright, my washing machine strong and my blow dryer powerful, so I'd much rather have a slightly higher line voltage than a slightly lower one!

brostenen wrote:

I have bought a modern C64 power brick a couple of months ago, and it induces noise to picture.

That's because those "modern" power bricks are done by people who may be able to create something like that, but have no clue about shielding, EMI, and all the tests that need to be done to guarantee proper operation.

The power supply that I bought was the one posted in the link below this post. I bought it specifically because it has over voltage protection, and because it is a modern design. (whatever that summs up to in the end) It should have an old school 9v AC line, yet the 5v DC line is according to the seller a switching one. And as I have the C64c with the shortboard, then I think the VIC-II runs on the 5v line. Well, this is what I can conclude from looking at the specifications on the sellers page of the power supply. And combining it with the knowledge that I have on the shortboard.

https://www.ebay.com/itm/112845541939?ViewIte … em=112845541939

Is there any way around all this? Some kind of electronics, that will make the switching output into something that "simulates" a linear DC power source?

There is an easy check for the quality of the power supply, as noisy power supplies induce a 16 kHz base line noise in the Audio Out through the SID chip. This can be seen in the spectrogram in e.g. Audacity. With a good power supply this is gone.
Unplug the monitor when recording to have a single power source on GND.
This is shown here in the SID Recording Tutorial: https://www.youtube.com/watch?v=JnjT6VV7DTg&t=1260s

elianda wrote:

There is an easy check for the quality of the power supply, as noisy power supplies induce a 16 kHz base line noise in the Audio Out through the SID chip. This can be seen in the spectrogram in e.g. Audacity. With a good power supply this is gone.
Unplug the monitor when recording to have a single power source on GND.
This is shown here in the SID Recording Tutorial: https://www.youtube.com/watch?v=JnjT6VV7DTg&t=1260s

Thanks for the link. I will be checking it out, as soon as I can source a cable for it.

Oh and you have to set Volume to 15, either in $D418 or use some music player with pause functionality, like SIDPLAY64. Setting screen to black helps also to get a clean signal.

However for just testing the induced system noise through power supply noise, even with VIC2 enabled you can see the difference.

elianda wrote:

Oh and you have to set Volume to 15, either in $D418 or use some music player with pause functionality, like SIDPLAY64. Setting screen to black helps also to get a clean signal.

Well... What you are describing there, is something that I know nothing about. I actually do not know what you are talking about, so I can not do what you are suggesting. All I know, is that the original power brick that were produced by commodore, do not produce any noise. So yeah... It is related to the new one. Going technical on the C64, like you are describing there, then I am lost.

Also the old ones produce visible and audible noise. There are new power supplies that are much better.

I have a modern Commodore 64 PSU made by Commodore4Ever (eBay), and the one breadbin C64 that I have started to do video noise on the RF and A/V ports. The RF Modulator in the C64 lost 2 electrolytic capacitors and ate the traces underneath (no damage to the motherboard), but the sad thing is, the RF Modulator controls the whole 9 yards for the A/V signals. I have another breadbin in an aftermarket case that doesn't have that issue, but when I made my S-Video cable, I got the Luma+Sync and Chroma wires mixed, and I fixed that as well, plus, I made my cable to have the noise reduction by using a fork on pins 2 and 5 to act as a ground and reducing the A/V noise, used heatshrink tubing after fixing the broken ground fork, and no noise or jailbars.

The funny thing about all this. Is that there is absolutely no issues or interference when using the original Commodore powerbrick.

Hmm, The nature of RF is mysterious as Voodoo magic. Lot's of stuff to take care of, hah. 😅.
That's why it is so hard to give any advice from the far, without knowing for sure what really is the cause of trouble.

Firstly, I'd make sure the new PSU really is the source of noise.
I'd use a cheap old pocket radio for this purpose.

Because Sometimes it isn't even the PSU that generates noise.
Rather, it just can't "filter" or "block" the noise it picks up from the mains.
In worst case, it's the TV set or a nearby device that is backfeeding that noise into the mains.

(When I saw the link for that C64 PSU, it wasn't what I had expected.
It rather looks like an aftermarket product that someone should think was
designed by former C64 users/fans with passion and was thoroughly tested before production.)

There's a good article (German) at http://www.dg0sa.de/snt.pdf ,
which gives an idea how many causes there are if your switching-PSU provides
noisy DC (it's about a lab PSU, though).

Been asking about this on other forums as well. Because I need max input on this particulair power brick.
On Lemon64, the verdict on this power brick is not good. It is mediocre in quality.
They provided me with some more info on what is actually inside the thing.

http://www.lemon64.com/forum/viewtopic.php?t=66126

and...

http://www.lemon64.com/forum/viewtopic.php?t=65873

Someone actually gave a link to pictures he took of the inside.
Perhaps someone here knows anything about these components.

https://photos.google.com/share/AF1QipODx8R_E … DdJUEZlMktqUEtB

EDIT:
I wrote the seller of the product, and he is saying that I am using a non shielded cable.
Yet that is not the case, as I have unshielded cables, and they are much worse than the one I normally use.
They are really thin cables, and using them, the original power brick makes noise.
Looking at the cables, the thickness and the video signal quality, I can only deem the one I use for shielded.
The seller of my cable even claims that it is a shielded cable, so I am quite confident on this.

So yeah...
Will see how it all turns out in the end. So far, the seller have not really come up with something constructive
on things that I have not yet tried. Well see...

Jo22 wrote:

Hmm, The nature of RF is mysterious as Voodoo magic. Lot's of stuff to take care of, hah. :sweatdrop:. That's why it is so hard […]
Show full quote

Hmm, The nature of RF is mysterious as Voodoo magic. Lot's of stuff to take care of, hah. 😅.
That's why it is so hard to give any advice from the far, without knowing for sure what really is the cause of trouble.

Firstly, I'd make sure the new PSU really is the source of noise.
I'd use a cheap old pocket radio for this purpose.

Because Sometimes it isn't even the PSU that generates noise.
Rather, it just can't "filter" or "block" the noise it picks up from the mains.
In worst case, it's the TV set or a nearby device that is backfeeding that noise into the mains.

(When I saw the link for that C64 PSU, it wasn't what I had expected.
It rather looks like an aftermarket product that someone should think was
designed by former C64 users/fans with passion and was thoroughly tested before production.)

There's a good article (German) at http://www.dg0sa.de/snt.pdf ,
which gives an idea how many causes there are if your switching-PSU provides
noisy DC (it's about a lab PSU, though).

Same issue on the CRT tv, as well as on the LCD tv. In the room were I am using my C64, there is
nothing else plugged in. So it is not radio noise from somewere else that are the cause.
When I am using the CRT, the LCD is not plugged in. And the other way around.

On both TV's the noise are still present, wether I use the RGB-Composit plugged into a composit
input on both tv's. Or if I am using a composit-to-scart plug in the scart port on each tv's.

Can the RF modulator still induce noise from a switching power brick, when I am using
a composit AV-Cable?

Hi again!

Sorry for the little necro, but there's something I forgot to mention.

- It came to mind just now, because I started repairing an old C64 that had a defective PLA chip..

Nowadays, I think, transformer-based PSUs are stigmatized and often "banned" because they are nolonger efficient enough.
For DC, at least, which most consumer devices are driven with.
Hence, switching-PSUs are all over the place.
They can't produce AC (normally), but cheap and in quantity DC with a bit of ripple here and there.

Unfortunately, older devices like the European NES or the C64 (has 9V AC line) do expect AC.

If fed with DC, they may *work* at first glance, but there's a problem that might occur (ok, some more with the C64, datasette etc). :

Electronic devices that accept AC do often contain bridge-rectifiers instead of a single diode.
If fed with DC instead of AC, they will be working under a higher burden and they efficiency will drop 50%.

Because, only two of the four diodes will be operational.
The other two will nolonger work, because there's no AC.

That means, that by using DC, it will make the bridge-rectifier work out-of-spec.
It will now be forced to handle much more current than before, because half of it becomes inoperable.
- Normally, it would toggle between two pairs of diodes.

Source: https://en.wikipedia.org/wiki/Diode_bridge#Rectifier

Edit: Picture fixed