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MAC-42

VIC-20 Power Supply Replacement?

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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.

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To my knowledge, the two-prong connector does not have a name nor is it available anywhere. You probably could replace the connector on the motherboard.

 

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.

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it uses the same end as those detachable radio cords or from an old playstation. if you get one with the squared off side, you can just round it off with a razor blade.

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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!

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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.

Edited by carlsson

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The pins on mine seem small, but I only have the 2 to compare, and they are both the same. This looks like the old standard boombox/portable radio plug from the 70's-80's.

 

On the plug end I found: Kawasaki KS-18. A little searching came up with this info:

 

CEA-LC1 =Phino PHS-205 =Kawasaki KS-18B =TY-123 AC power cord 7A 125V 16x8MM, 7MM pin center

($6.21)

 

From here:

 

http://www.kenselectronics.com/lists/pwrcord.htm

 

You may be able to use these other numbers to track down what you are looking for.

 

These aren't my prettiest examples, but they were the ones I could get to the easiest!

 

 

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post-37051-0-93042500-1403781560_thumb.jpg

 

post-37051-0-72600000-1403781561_thumb.jpg

Edited by TheRealAnubis

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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.

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Greetings from 2021!

 

So you can now 3D print replacement plugs for the two different types:

 

Divided version:

https://www.thingiverse.com/thing:4678324

 

Open version (i.e. can also use figure-8 plug):

https://www.thingiverse.com/thing:4658989

 

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).

 

You lose 9VAC on the User Port, etc. but I still have the option to use a normal power supply if I ever need that (unlikely?).

 

/Brett

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Final result - replaced the 2364 kernel ROM with a 27C128 ... down to 0.87A (when doing nuthin').

 

I've put the rectifier heatsink back on as it still generates a bit of heat when using the normal input socket (AC or DC).

 

/Brett

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Posted (edited)

Next step will be to replace the 6502 and 6522 with CMOS equivalents - this should reduce power consumption further, and no need for heat sinks?

 

6522: W65C22N6TPG-14

6502: W65C02S6TPG-14 (needs an adaptor board ... https://github.com/TheByteAttic/6502-to-W65C02S-adapter)

 

And finally, as the two remaining 23XX ROMs seem to be quite power hungry, replace them with 27-series versions too?

 

Keen to see how much the power consumption reduces to then.

 

Sorry @MAC-42 ... I didn't mean to hijack your topic

 

Edited by asdf87
daughterboard -> adaptor board

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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.

 

Jim Brain has the ROM-el 2364 but I don't know if Flash memory consumes less power.

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28 minutes ago, carlsson said:

Jim Brain has the ROM-el 2364 but I don't know if Flash memory consumes less power.

I'm just using simple 23-to-27 adaptor boards ... works well for the kernel (2364 -> 27C128) but I've had no luck swapping the character ROM out ... tried replacing the 2332 with a switchable 2764 that had both VIC and C64 fonts ... got some weird effects.  

 

https://github.com/SukkoPera/Open2327RomAdapter

 

Good note about the opcodes ... will bear that in mind!

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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).  

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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.

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Success!  I finally got my 3D printer and printed out the PAL connecter that EMD69 had designed.  As the original video was in Italian it took a bit of trial & error but I finally figured it out.

 

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.

 

Finally for the 2.1mm DC power socket, I used a bunch of pre-made leads from Aliexpress ... search for something like "dc power jack pigtail".

 

/Brett

 

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On 5/6/2021 at 9:29 AM, DistantStar001 said:

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).  

 

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 ;)

 

/Brett

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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.

 

/Brett

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On 5/1/2021 at 3:31 AM, asdf87 said:

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).

 

You lose 9VAC on the User Port, etc. but I still have the option to use a normal power supply if I ever need that (unlikely?).

 

I have a VIC-20 that I don't know if it works, and I don't have 2-prong power supply.  I find your mod intriguing.  Do you have to add second power switch? 

 

I was watching this video from Adrian Black where he temporarily powers a VIC-20 from a bench power supply:  https://www.youtube.com/watch?v=BGnNlVzUCZM&t=528s

 

I noticed his VIC-20 runs even though the voltage regulator is gone.  I know little about electronics, how is this working?

 

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On 11/22/2021 at 1:02 PM, djc6 said:

 

I have a VIC-20 that I don't know if it works, and I don't have 2-prong power supply.  I find your mod intriguing.  Do you have to add second power switch? 

 

I was watching this video from Adrian Black where he temporarily powers a VIC-20 from a bench power supply:  https://www.youtube.com/watch?v=BGnNlVzUCZM&t=528s

 

I noticed his VIC-20 runs even though the voltage regulator is gone.  I know little about electronics, how is this working?

 

The original VICs used a 9V AC power supply - the 9V was used for the Datasette and expansion port.  It was also converted internally to 5V DC (via the rectifier and regulator).

 

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).

 

Oh, and in the case of a US two-prong VIC, then I just make up a converter cable using a figure-8 power plug and either a 2.1mm socket or a 9-pin DIN socket (so you can use a regular/modern C64 PSU)

 

/Brett

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Edited by asdf87
grammer

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Less blurry picture of the 2.1mm socket - note how it just touches the upper case.  I've also re-sprayed the metal bracket of this one as it was quite worn and looked horrible.

 

Note that the extra switch is for the kernel, switching between the normal VIC kernel and JiffyDOS (because JiffyDOS doesn't have Datasette support)

 

/Brett

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Edited by asdf87
extra info

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It seems the power switch on my VIC-20 won't budge - anyone know of a replacement that fits?  Its stuck in OFF position.

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