Motherboard versions

[Gyro Gearloose]

How many versions of the VIC-20 main board exist, and which is "better"?

The 1981 version with 11 1Kx4 chips and on-board 5V regulator runs hot, but avoids the unreliable Commodore power brick's 5V regulator.

At least when a 1981 VIC-20 5V fails you can replace that regulator or replace it with a switcher.

Then again the other versions let you use the same power supply as a C64.

Any other differences?

[orion70]

IMHO, from a non-hardware guy point of view, the last CR board is better. Less components, less prone to time passing by, same functionality. Easier to analyze if you have problems, maybe also easier to fix.

Of course, one has to buy a modern PSU.

[srowe]

Hardly authoritative but the three original VICs I have seem to have a far better quality video output than the (single) CR. This is without the S-Video mod.

[orion70]

In my experience, this holds generally true for factory machines, but if you play with internal triggers there's no substantial difference when using a crt monitor.

[Gyro Gearloose]

I've been going over my vast collection of stuff and unearthed three VIC-20s. Only one is the old 9VAC-only version. I don't have a 9VAC power supply anymore because decades ago I took it apart to use the transformer for a large C64 power supply.

It looks like I can power up that VIC-20 by simply injecting 9VAC into the user port, bypassing the input filter, switch, and fuse however.

Hmmm.

[orion70]

It's the way that the Arfon Micro expansion uses to power up the VIC.

[Gyro Gearloose]

Very interesting. It eliminates the power cable sticking out when the VIC is in a chassis. Never heard of that particular chassis.

I suppose you can push the idea to a level of absurdity that I enjoy: a VIC-20 powered up by the user port could power up another VIC-20 through the first VIC's power connector. Then you can turn on the second VIC-20 with the power switch of the first one.

[orion70]

Crazy idea! I guess you have to supply an adequate amount of Ampere

[Gyro Gearloose]

Yeah but the limit is how much current a user port contact can carry, the PCB traces, the 9VAC wire, etc.

It would probably work for a while. I like weird things but this is not very useful, more of a "hmm" thing.

Since the amps would flow through the first VIC's fuse, that limits the number of downstream VICs to one in any case.

[Noizer]

Maybe you need something like that? https://www.keelog.com/de/power-supply/

[Gyro Gearloose]

Nah I built my own supplies over the decades.
I just wanted to know how many versions of VIC-20 main board exist? Seems it's only two?

[srowe]

I just wanted to know how many versions of VIC-20 main board exist? Seems it's only two?

There are probably minor variations but yes there's the original model that takes just 9V AC and the CR model that needs a dual voltage PSU.

[16KVIC20]

Then again the other versions let you use the same power supply as a C64.

Do they though? I always thought that the VIC 20 PSU is known to fry a C64. I have the CR VIC 20 (same type I had first time round in the 80s) that has the beige wedge shaped PSU. My C64 has the exact same brick. I have them labelled up to avoid accidents. As I understood it, you can use a C64 brick on a VIC, but not the other way around. Of course< i could be wrong about this.

[orion70]

As I understood it, you can use a C64 brick on a VIC, but not the other way around. Of course< i could be wrong about this.

Yep that's right. This has been confirmed several times here in Denial.

[16KVIC20]

Thanks Orion70. I thought that was the case.

Now I have a perfectly useable PC PSU from 18 years ago that, if I knew how, could become the new PSU for my VIC 20. I'm pretty sure I've seen this has been done. Anyone know how?