C64 power woes

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Rixa

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I hear that the old C64 power bricks are quite likely to fry the computers that they power when they finally break. I'm still using mine, though it does make me nervous. There is even this unpleasant plasticy smell when it gets warm, but it has worked fine so far and isn't getting too hot to handle even with an 1541 Ultimate connected. It is even supplying sufficient power to run the latter reliably, which has been a problem for many.

Nevertheless I would like some sort of a replacement. Are there any modern options that are passively cooled? I wouldn't like to add any humming fans to an otherwise silent computer. The power requirements are not that high and the original brick has lasted this long without any fans and a design that doesn't really look like it's built to dissipate heat, so it should certainly be doable.

Meanwhile, I have a perfectly silent C128 power source that is said to have a much safer design and is even more powerful. I never use the C64 and the C128 at the same time, so I could just as well use the same brick for both if it wasn't for the different connectors. An adapter cable to plug a C128 power source into a C64 would be brilliant. Has anyone built such? I'm not sure the rectangular connectors are available anywhere, especially as cable-mountable females. Would probably need to scavenge one off a dead mobo and case it somehow.

Unfortunately I also can't build things. :Doh:
 

SkydivinGirl

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I sincerely share your concerns. :( There's been a discussion in this thread on Lemon64 of a person who is trying to design a new replacement power supply. Unfortunately, as so often happens, the designer's life is getting in the way of the project. He's putting his family first, which is what he should do, but the community definitely needs an alternative.

Maybe some of the electronic geniuses on AmiBay could come up with some sort of ATX to C64/C128 adapter. I would buy a few of those!

Take care,

Heather
 

AmiNeo

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This might be good... and given that a C64/128 (I would hope atleast :LOL:) would be very low wattage, you'd probably be able to make some tiny ones from the smaller ATX 150W and 200W type PSUs that are designed for the smaller form factor cases, or even a laptop psu??? :blink: :unsure:...
 

jvdbossc

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Without opening up and breaking warranty of the C64:D:D you still need 9v AC where do you get it from atx, I think nowhere, of course some DC to AC can be created, but that is difficult I think. Hope that Zetro or Rkauer show up, they might have the proper knowledge to explain more, but expect extra money.

I would be the first in line for such a psu, because I blaim the 240 instead of 220 for general failure.
 

gazcbm

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I was chatting to the guys over at the UK Commodore computer club about the very same thing a while ago. Several of them had bought a PSU that has since stopped being built, but it catered for (from memory) about 4-5 Commodore machines/disk drives. It was essentially the Swiss Army knife of PSU's and was powerful/stable enough to be run machines with the SuperCMD accelerators.

I will drop them a message to see if they have any more information

(y)
 

JLPedro

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Well as far as i know the C64 needs 2 x 9v and 1 x 5v , you can use a cable from an faulty c64 psu and hook it up to an ATX psu (using and HD molex connector), use 2 x 7809 (12v to 9v) power converters to get the 9v needed from the 12v on the molex ATX connector.

And the pinout for the C64 connector:

http://www.allpinouts.org/index.php/Commodore_C64_Power_Supply

Hope it helps, and corrections welcome!
 

gazcbm

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I think the problem lies in the 9v that must be AC instead of DC.
 

gazcbm

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:nod: Dont worry, I did exactly the same!
 

Merlin

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Captain Obvious says....

So why not just fit a small 9v AC transformer into an ATX power supply to provide the 9v AC...??
 

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jvdbossc

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Merlin, that is exactly the point there is no AC on PC PSU ATX.. I was hoping for some more skilled electronic guys to show up..............
 

Merlin

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Jurgen mate,

If all you are missing is 9vAC, then just fit a separate 9v transformer in the case and hook it up to the mains inside the ATX PSU.

Something like this; it's an 18v transformer, but you would only need to use one of the windings. Or even this one.
 

gazcbm

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Nice linkage.. and should be easy to hook up.

I would still be interested in buying something like I saw the CCUK guys using though.
 

Merlin

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@ Gazcbm

Really, it doesn't need to be that complicated.

If you select a 9v-0-9v mains transformer with enough wattage to power the C64, then a bridge rectifier, a couple of smoothing caps and a 78L05 for the 5v line across one of the 9v windings will get you 5v DC and the other winding can be left to provide the 9v AC. A mains fuseholder later and wallah!!

How much more complicated than that do you want it?

@ Jurgen

I'm gutted that you feel that I haven't the skillz.....:(

:LOL:
 

SkydivinGirl

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If you select a 9v-0-9v mains transformer with enough wattage to power the C64, then a bridge rectifier, a couple of smoothing caps and a 78L05 for the 5v line across one of the 9v windings will get you 5v DC and the other winding can be left to provide the 9v AC. A mains fuseholder later and wallah!!
:blink::blink::blink:

I'm so confused. :) I agree with GazCBM that a power supply that would run multiple devices would be the cat's meow. :D

Heather
 

TheCorfiot

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And just to complicate things a bit more,,,

+12V DC into the 9V AC will also work, think about it..;)

The rectifier will only operate on the positive cycle as that is all it is getting in the case of a DC input, it will still feed the unconverted DC supply across the smoothing capactor and then into the regulator, which may get a bit warmer due to the slightly larger voltage comng through.

I like Merly's idea though, that's pretty much how the original Commodore PSU's are.

@Jurgen, hope that was technical enough my friend :LOL:

TC :cool:
 

jvdbossc

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@ Merlin,

I should be more carefull, It was a dangerous expression, I did mean our favorite joy is not on the electronic side, I did not want to judge on skills :-(
But I see you understood that it was not about that :laugh: You have an excellent record by the way me thinks.

Corfiot,

MM interesting, I understand it passes the rectifier or diodes, then it goes to the lm's. Since I think (please correct me if I am wrong, I am not the electronic guy) the 9VAC will be about 10VDC there is only 2V difference. Not much to talk about then, we could use 2 rectifire diodes for a 1,4 v drop then ?

Is it going to work with all boards, as I understood some SIDS need 12V is going to be delivered there to then, or will it be cut by the electronics to create the normal 9 AC to 12 DC ?

Looks like I have some work to attent if this is it.
 

Merlin

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@ Jurgen

The circuitry inside the C64 takes the 9v AC, puts it through it's own rectifier circuit and ends up with 12v to feed the SID.

By feeding 12v DC in, all you are doing is making the internal rectifier circuitry of the C64 redundant, although it may get a bit warm.

If you Google around a bit, there are pictures that show where you can tap a 12v DC feed directly onto the 64's main board, so you could power the lot from an ATX PSU; however, there may not be enough current drawn from the ATX PSU by the 64 for the regulation to work totally correctly.

Edit: I've attached a quick sketch of the circuit I was talking about earlier that would give you 9v AC and 5v DC from the same transformer. It's a bit rough but you get the idea.
 

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Rixa

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I have been told that without AC the computers realtime clock will not tick. I'm not sure what this means in practise, but it suggests to me that DC for AC is at best an incomplete solution, even if the SID will be happy.
 

Merlin

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One thing intrigues me. AC voltage in the UK is 240v at 50Hz, although TC informs me that some countries have AC at 60Hz. If the AC controls the realtime clock, does this qualify as an overclock...?? :blink:

:LOL:
 
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