Making a new C=64 PSU

[Retrofan]

Hi:

I want to make a new power supply for my old Commodore 64 breadbin before it's too late.

The Commodore 64 requires a power supply that provides both 9V AC and 5V DC.

I'm thinking in buying this 9v AC adaptor: 1A/1000MA 9V 9VA AC/AC OUTPUT MAINS POWER ADAPTOR/SUPPLY/CHARGER/TRANSFORMER

And this 5volts DC one: 1 St. Netzteil: Impuls; 15W; 120÷370VDC; 85÷264VAC; Ausgänge:1; 5VDC; 3A

First I want to know if they will be ok to make a new power supply and in second place I would appreciate if someone could post some picture about how to connect it, where to add some fuses, which, etc.

Please remember that any explanation has to be easy to understand for everybody as I think that any help here will be useful for others.

[AmigaBoy]

<offtopic>
This is a little off-topic since you want to build a PSU, but if you or anyone else wants to buy a newly built PSU, Ray Carlsen builds and sells them from his website at http://personalpages.tds.net/~rcarlsen/custom%20ps.html

I've ordered both C64 and Amiga ones in the past. Both were high quality and were completed within days.
</offtopic>

[puppypc]

Those two adapters sound fine to me. I have no soldering experience and built my own a few years back the same way. I didn't add any fuses myself, since the modern wallwarts "shouldn't" malfunction any time soon. If you make one without a fuse, you can always pick up the kits folks at lemon64 (and I assume amibay as well) make, for like $15 or $20 if I remember correctly.

I will tell you that this conversation occurs a minimum of once a week on lemon64's message boards, and the documentation over there is very very good (they have a lot of experts, who love to share knowledge!). I'd recommend just spending half an hour using the search function over there.

[Ffin]

There's a good project here:

[ Show youtube player ]

Links to shematics and write up in the description.

[Retrofan]

This is what I've done:

















I haven't tried it yet and I want to add the final touch.

I will check the pinout and the cables first. Edit: I see that in my PSU, the white cable is pin 5 and it has to be +5V, but I've heard about pin 5 brown. My brown cable is pin 6 instead, for 9Vac:

Pin 5 white 5V+
Pin 2 green 0V
Pin 6 brown 9V~
Pin 7 yellow 9V~

This is the best image (female socket), taken from my book:



Let's hope that I won't fry anything.

Edit: I've received a tip and I will use it:

ElectronAsh​ - If you add a fuse, and a chunky 5.6V Zener diode to the +5V line, it would be enough. Very cheap to do
​A Zener diode is a good idea (after a fuse), as it should at least prevent an over-voltage, which is obviously the main killer of the C64.

So I think I'll add another fuse to the 5V line and that zener diode.

[Retrofan]

Just to comment also about this new Psu that I've bought (I've got four C64's). I think it has a good price and it also has a cable long enough:

https://www.ebay.es/itm/New-Commodor...YAAOSwYwJaDXiD

Edit: I've checked the continuity of the cables and it is ok with the pins now, but I can't check the volts of each line because my multimeter has a blown fuse and I'll have to wait for a replacement. In any case I've switched it on while connecting it to one of those new C64's power savers and the led turns on ok. I won't try it yet with the C64.

[Retrofan]

The power saver I bought at Ebay for the PSU was needing a box, so I've bought an empty C64 cartridge and I've adapted it using the dremel:

[Retrofan]

I've finally added another fuse for 5V and a Zener diode after it.

And I've added my final touch: A voltmeter/ammeter with LED display. And as Ray Carlsen says:

Originally Posted by Ray Carlsen

For me the current measurement is the most important as it
tells me immediately if the board I'm working on has shorted chips.
Blank screen is the most difficult symptom to diagnose since many
things besides shorted chips can cause it, so I use anything I can
to assist in the diagnosis. Note that there are half a dozen
different C64 boards and each has a normal current draw, anything
from 700mA to about 900... and all are normal. Above that, look for
shorted chips.

[dlfrsilver]

Originally Posted by Ffin

There's a good project here:

[ Show youtube player ]

Links to shematics and write up in the description.

This is the absolute best PSU for c64 that you can build yourself.

[Retrofan]

Well, that's you, LOL . I prefer mine instead. Original cover, newer and much improved components from the original, fuses, Zener diode and a LED display for volts and current to give a modern look and at the same time some important information while keeping the original retro look .

Edit: The diode wasn't working right so it's out of the project now (well, I've added it to the mobo instead http://eab.abime.net/showpost.php?p=1221362&postcount=7) . I asked Ray Carlsen and he told me:

Originally Posted by Ray Carlsen

If you're talking about the old linear "brick" power supplies,
that might be true, with some changes. When the brick fails via
over-voltage, you do need some kind of protection for the computer.
That's why I invented the Saver, a module that cuts power to the
computer before any damage is done. A small zener diode will fail
(short or blow apart) when subjected to that kind of PS failure.
The diode, if it were big enough, should be wired across (in
parallel with) the +5VDC output, not in series.
Such protection is not really necessary for a switcher as
they usually have over-voltage and short circuit protection
built-in. All my power supplies do. Switchers are inherently more
stable and are more efficient so they don't run hot, both of
which are problems for the analog brick.

So now the PSU is working nice and the current meter first tried with a small light bulb as a load showed correct current at .025A (250mA). With the C64 it showed a normal 850mA. There are half a dozen different C64 boards and they each draw a different amount of current from 700mA to almost 900. So this meter appears to be quite accurate.

And... another thing: My working original C64 PSU suddenly died. At least it didn't fry anything, but I will have to use it now to make another PSU just like the one I've made and shown in this thread.


Edit: About this psu, it was giving problems with the Robocop II cartridge, showing bad graphics after a few moments playing.

So I tried with shorten cables and the Robocop cartridge was having the same problem, so then this afternoon I've dismounted another psu that works right with that game (a psu that I bought at Ebay) and I've installed it instead of the ones I was using, inside the C64 psu case.

And... the Robocop cartridge was showing the problem again....

So what I've done is to desolder the 5v cable that the voltmeter display board uses that I had connected to about 6 cms of the cable that comes from the 5volt DC psu and I've connected it directly to the point where it delivers 5v in the board.

I just thought/think that connecting it as it was, then it was drawing more power from the 5v cable that goes to the C=

... And it works now. Robocop works without any problem.

BTW I see that using the Ultimate II cartridge the current changes a lot. I suposse that's normal.

[ Show youtube player ]

And I've changed the psu din connector using a Rean with golden pins:

EDIT: ... BLABLABLA...
ALL of the images just disappeared from the site, so I will post some of them here now.
Yep, you can call me "The man with the Caliper view" or something :

















But I changed some things afterwards, just as commented.