Replacement Commodore Key

[Tea Rochlitz]

Ihave previously covered other replacement parts for the Commodore 64 like the new Commodore 64 keycaps and a replacement 6502 (not exactly a replacement). Limited runs of a VIC II Replacement are in the works as well. Now, there is a modern SRAM memory replacement module for the Commodore 64 and this is something I think is quite exciting. The supply of old parts are not going to hold out forever and if vintage tech enthusiasts can utilize modern components to keep these old machines running, all the better!

I really want to commend the designer of this product in that the same PCB is used for both 250407 and 250425 motherboard chip arrangements. The difference looks to be only a few millimeters and provisions have been made accordingly. This board can also be purchased without the pin headers installed for a more DIY experience, if that is your thing. I can also imagine that this would also be useful if you are someone that performs a lot of Commodore 64 repairs and want to keep a single stock item for a variety of motherboards.

Another benefit to this board is that it does fix the VSP-bug for which some Commodore 64s seem to be afflicted. That will open up the ability for certain demos and games that take advantage of this DMA-delay. So, in effect, this could be a very reasonable upgrade or fix for a buggy Commodore 64 as well.

It certainly is a fascinating how this is implemented. I do think it would be cool (though I realized probably very impractical) if somehow an REU could be integrated into this with the maximum possible memory, 16 MB, available to the system, such a thing would leave the expansion port for other things, potentially.

I picked up a VIC-20 on the Evil Bay some months ago. I borrowed a friend's VIC-20 for its power supply and video cable to test mine, and all worked well. Great. To top it off, my friend let me keep his VIC-20, too. Total score!

But there's still this one VIC-20 now that has no PSU. Yes, I can go buy a replacement without even coming close to breaking the bank. But I'm curious about something. I can take my Atari 600XL's Ingot PSU, clip off the 7-pin DIN and solder it to a modern 5V 2amp PSU that I have laying around from some old phone or something. Hey presto, new, modern PSU.

Is there a way to do this with VIC-20s? Heck, is there even a place to purchase the female 2-pin connector to match the model of VIC-20 that I have? I've looked high and low (I think) and have not found anything even remotely like it. If this is not possible, I'll break down and find a proper replacement.

This VIC-20 is of the first generation and requires 9VAC, about 2-3A. In theory the same power supply as you use with an Atari 1050 floppy drive should be enough to power the VIC, but you would need to replace the connector somehow. Of course you can find several other sources of 9VAC, at least up to 2A. Someone on the Denial forum a few years ago replaced it with a DIN connector and fed the 9VAC 1A from a newer VIC/C64 DIN power supply. It was barely enough to power the base system.

Thanks for the information, folks. I hadn't thought about just yanking the old connector and replacing it on the board with something else. And I knew that the shape was nagging at me, because it was on some level reminding me of an old tape deck I had back in the 80s. Good thoughts. Thanks again!

There are two kinds of two-prong connectors. One smaller with thinner pins (Japanese VIC-1001 and very early VIC-20's?) and one bigger with thicker pins (all other two-prong VIC-20's, both NTSC and PAL). I checked a said radio cord, and at least those I've got need to be cut open in the middle to be able to insert it into the thicker two-prong, plus of course I'd need to feed the required 9VAC.

Yes, that is the connector that I refer to as the earliest, but perhaps it is more common on NTSC VIC-20's than I thought it is. There is a later variant of the two-prong with a "bar" between the two pins, which would make the standard cord much harder to fit. An image search with Google may yield a few results, now that you know what to look for.

Or hm.. perhaps the variant with the bar separating the pins only was available on PAL VIC-20's? Is the 50/60 Hz line frequency used anywhere inside the computer, for proper timing of the VIC or VIA chips? As far as I understood the 9V AC is converted into 5V DC etc inside and 9V AC only on the user port for external applications. Things like modems that may want the right line frequency usually had external power supplies anyway as you can only draw so many mA from the user port.

I've also done the following mod. - added a 2.1mm socket which bypasses the rectifier and goes straight to the regulator - as I've also replaced the LM323 with a switching equivalent, there is no more heat being generated by either the regulator or the rectifier. And it draws under 1A (if not using a datasette).

Just watch out for eventual software that uses unofficial (illegal) opcodes. Mainly those would be scene demos. I seem to recall that the instruction set of the 65C02 is not identical to the 6502 but for all programs that only use official instructions it will work as expected.

If it's an American version, then the prongs are the same as a power cord for most electric razors. You could do what I did, cut off useful end and solder on a barrel jack to the other. After that, any 10-15 volt supply at 2.5 amps will work (even if it's DC).

As seen by the pics, this is a PAL model with the divided connector where a C1/C2 or C8 connector doesn't fit. Over here someone came up with a solution involving two RCA connectors, possibly shaved a little on the isolating plastic, to work as the power connector if you can't print or otherwise obtain a proper one.

I used an M3 nut and an M3 x 12mm countersunk bolt to hold them together - the nut wouldn't fit into the hole for it so I used a longer M3 bolt (say 20mm) to pull the nut into the hole resulting in a tight/permanent fit.

For the connectors I broke them out of a terminal block (8mm pitch) and removed one screw from each - the other screw remains to hold the 2.1mm socket lead. I used what I had lying around but it looks like Hylec HYKS-02412PP is similar.

I've gotten my VICs down to under 1A (no Datasette obviously) - if you're using DC then the rectifier wastes a bit of power (and waste heat) so I bypass it and go directly to the regulator. But first I always chuck the LM323 (well, I keep them) and put in a modern replacement, saving a bit of power & heat again. The 23xx ROMs are also pretty inefficient it seems - replacing the kernel ROM at least with a 27C128 saves a bit of power & heat yet again. And, I've just got myself a bunch of modern CMOS 6522s so am interested to see if I get reduce power consumption further

These are the two final designs I've settled on ... one with a 2.1mm DC power socket so you can use any 9V (AC or DC) plug pack, and also one with a 7-pin DIN socket so you can use an existing modern (or vintage) VIC/C64 power supply.

So if you aren't going to use a Datasette (or something on the expansion port that needs 9V) then you could bypass the rectifier AND regulator and feed 5V DC directly to where the rectifier would've been outputting its 5V.

In my case, I prefer to just add that 2.1mm socket ... I've done it a few ways ... wired directly to the rectifier input (so on/off switch has no effect), wired directly to the regulator input (using a 9V DC only supply, saves wasted heat on rectifier) or, more recently, across the 2-pin power socket.

I think I prefer just wiring it across the input socket - on/off switch works, doesn't matter if you have an AC or DC power supply, you still get the protection of the fuse, you can use a Datasette/expansion port. I've made other improvements that reduce the heat/power consumption so don't mind the wasted heat in the rectifier. Hopefully the attached photos are helpful.

If attaching the 2.1mm socket, be very careful about positioning ... the top case overhangs the metal bracket by a few mm ... if you position the 2.1mm socket too high then it might get in the way of the top case (not a big deal, just do some small filing).

Hello, im new here, i saw your post about a vic 20, 2-prong power connector that you 3-d printed, i also have a vic 20 with that 2 prong setup, but i dont have a psu, does anybody know where to find the 3d printed connector? (i have not found it on thingiverse)

Greetings,

Hello, im new here, i saw your post about a vic 20, 2-prong power connector that you 3-d printed, i also have a vic 20 with that 2 prong setup, but i dont have a psu, does anybody know where to find the 3d printed connector? (i have not found it on thingiverse)

After a few months of patiently waiting for the postal services to deliver small packets from around the world, I managed to gather a total of four different C64 RF modulator replacement devices. For easy swapping between the modulators, some sockets were installed into my Commodore 64 SixtyClone Replica. The initial tests were carried out using my good old Bang and Olufsen mx4000 CRT TV. This Danish design beauty has superior sound in comparison to most modern-day TV-sets. But even more importantly, the video signals from the C64 match the image resolution of the TV perfectly. I therefore had a really hard time differentiating between the signal changes among the different RF modulators. However, as most people use flat-screen TVs (with an upscaler) for their C64 adventures, I therefore did all my tests using such a device and an LCD screen. Below is a small review of each of the four boards. Welcome to the C64 RF modulator Battle!!!

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