I got a Commodore Vic-20

Passport.mid · Post by **Passport.mid** » Sat Apr 14, 2018 6:10 pm

Hello, I have recently got a Commodore Vic-20 in the box off of Ebay for $97, and it's in great condition from what I saw. It has cables, the computer; and manual from what I saw. I'm currently waiting for it to ship over to my location, here are some images of it from the Ebay auction.

Post by **joshuadenmark** » Sun Apr 15, 2018 12:38 pm

Fine looking Vic

hope you receive it soon.

English Invader · Post by **English Invader** » Tue Apr 17, 2018 3:50 am

Thanks for sharing and welcome aboard.

Sorry to rain on your parade but I would recommend that you obtain either a voltage limiter (marketed as the Computer Saver) or an alternative power supply before turning on your VIC. You have the later cost-reduced model with the C64 style PSU and these power supplies have a high failure rate and, when they go, they blow most of the chips on your motherboard as a farewell gesture. Thousands of VIC-20s and C64s have been ruined as a result of this. The problem has been well documented over a number of years; just google "c64 over-voltage" for the low-down.

highinfidelity · Post by **highinfidelity** » Tue Apr 17, 2018 3:55 am

How is it that I've read exactly the opposite, that 64 PSU are safe and that VIC-20 specifc PSU aren't?

English Invader · Post by **English Invader** » Tue Apr 17, 2018 4:24 am

highinfidelity wrote:How is it that I've read exactly the opposite, that 64 PSU are safe and that VIC-20 specifc PSU aren't?

Care to elaborate on that?

My understanding is that the only danger from the original VIC PSU is that it's internal and placed right beside the cartridge port. It doesn't damage the VIC but might damage your cartridges if you leave them in there for too long.

beamrider · Post by **beamrider** » Tue Apr 17, 2018 6:08 am

I suspect he means C64 PSUs are safe on the Vic 20 but Vic 20 PSUs cannot safely power the C64 due to its higher current demand.

Of course neither of them are safe when faulty due to age.

There are new PSUs available on EBay at the moment...

https://rover.ebay.com/rover/0/0/0?mpre ... 2636456654

highinfidelity · Post by **highinfidelity** » Tue Apr 17, 2018 7:12 am

It's on the Denial Wiki, voice "Power Supplies":

People who accidentally or intentionally powered their 64 with the power supply of a VIC-20 revision C often damaged their 64 when the 5V regulator in the power supply failed and output excessive voltage resulting in damage to the 64's CMOS DRAM chips.

Doing the opposite - powering a VIC-20 revision C with a 64's power supply - is perfectly safe.

These power supplies are also very susceptible to failure. All electronic components are sealed in epoxy inside the brick and cannot be easily repaired.

I don't know what you eventually get from this paragraph, I get this:
VIC20 PSU - fragile regulator, may fail anytime, failure will destroy the computer;
C64 - regulator OK, safe under all conditions.

beamrider · Post by **beamrider** » Tue Apr 17, 2018 7:45 am

I don't get that at all.

A C64 PSU is not immune from over-voltage risk due to age.

cbmeeks · Post by **cbmeeks** » Tue Apr 17, 2018 8:07 am

I used my C64 (and VIC-20) for years "living dangerously". Meaning, using my working C64 PSU in both machines. NEVER had a problem. Still works today.

Don't get me wrong, I read the horror stories of them frying machines. Still, I thought, "mine works great...why bother?".

THEN I watched an episode of 8-bit Guy where he literally fried his C64 while filming. I then realized that I've been a fool. It *WILL* happen eventually. So why risk it?

I then unplugged my C64 and swore it would never see power again until I had a reliable source with over-voltage protection. So I ordered (and built) a Sav64 and now I'm a happy camper.

I've been talking to the guy that designed the "NuBrick" PSU too. I suggest looking him up. He has a modern PSU replacement (similar to the Ray Carlson version) using new parts.

His name is Kevin Ottum. Not sure if he wants me to give his email out. But he can be found over at Lemon64 with this tread:

http://www.lemon64.com/forum/viewtopic.php?t=67717

groepaz · Post by **groepaz** » Tue Apr 17, 2018 8:49 am

is that Sav64 the placebo thing that will safely cut the power with a relay.... a couple hundred microseconds after the C64 was fried?

that said, yeah, dont use the old PSUs. dont use those silly "saver" circuits either. a plain simply new modern PSU will do the trick (even more so for the vic20)

cbmeeks · Post by **cbmeeks** » Mon Apr 23, 2018 9:57 am

groepaz wrote:is that Sav64 the placebo thing that will safely cut the power with a relay.... a couple hundred microseconds after the C64 was fried?

that said, yeah, dont use the old PSUs. dont use those silly "saver" circuits either. a plain simply new modern PSU will do the trick (even more so for the vic20)

Well...I'm not sure on that one. I do admit, I bought it without much research. I sure hope it wasn't. I would love some second opinions on this.

However, in the meantime, I have bought a Nu-brick which does exactly what you said. It's a mixture of new DC PSU and AC transformer. From what I understand, the DC component has all of the protection circuits you would expect.

But I'm no expert.

groepaz · Post by **groepaz** » Mon Apr 23, 2018 10:56 am

ah modern circuit should have a crowbar circuit to prevent overvoltage on failure... even THAT can not be fast enough in some situations, but a relay certainly isnt. a relay based circuit can only ever protect against overvoltage which raises relatively slow while the PSU is being used - however the typical failure mode of those cbm powerbricks is that you turn them on and get the full blast instantly.

English Invader · Post by **English Invader** » Mon Apr 23, 2018 4:42 pm

cbmeeks wrote: Well...I'm not sure on that one. I do admit, I bought it without much research. I sure hope it wasn't. I would love some second opinions on this.

I bought the original Computer Saver from Ray Carlsen (the original inventor) as detailed here:
http://sleepingelephant.com/ipw-web/bul ... f=5&t=6598

I'm not an expert either but Ray certainly is. US Army trained and was dealing with electronics before most of us were born.

groepaz · Post by **groepaz** » Mon Apr 23, 2018 5:15 pm

US Army trained and was dealing with electronics before most of us were born.

that doesnt make this circuit any better really

no doubt he has published some good stuff - but there is no doubt some of the things he made are a bit questionable either.

cbmeeks · Post by **cbmeeks** » Tue Apr 24, 2018 6:22 am

groepaz wrote:
US Army trained and was dealing with electronics before most of us were born.
that doesnt make this circuit any better really no doubt he has published some good stuff - but there is no doubt some of the things he made are a bit questionable either.

So, groepaz, what do you recommend? I'm using the nu-brick now. Which uses a modern switch mode PSU for DC. I have no idea if it has a crowbar circuit or not.

But is there any product you recommend we use that is new?

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