Re-Using C64 power supply Sid v3

[padjoe.thornton]

Hi,

I'm building a midibox sid with 2 sids (stereo) and one core first and then after testing I'm hoping to add the minimal control surface, I'm reusing the C64 psu, and it's the 8580 chip

I'm looking at the website at all options and these all came up,

For fear of getting this wrong, although I would be testing it with just the ic sockets in each, I'd like to know which option I should work off?

http://ucapps.de/mbhp/mbhp_sid_c64_psu.pdf

http://ucapps.de/mbhp/mbhp_4xsid_c64_psu_optimized.pdf

or this which is what I'm thinking to use;

http://ucapps.de/mbhp/mbhp_8xsid_c64_psu_optimized.pdf

and this means I need to remove the 7805 from the core?

[padjoe.thornton]

Also in this

http://ucapps.de/mbhp/mbhp_4xsid_c64_psu_optimized.pdf

and this

http://ucapps.de/mbhp/mbhp_8xsid_c64_psu_optimized.pdf

where multiple sides are used there is no connection to junction 1 of the core?

I'd like to know why?

Thanks

[Flemming]

I'd like to know why?

Because the core gets power through J2 instead

[Flemming]

or this which is what I'm thinking to use;

http://ucapps.de/mbhp/mbhp_8xsid_c64_psu_optimized.pdf

and this means I need to remove the 7805 from the core?

That one is considered the best solution for power with as little noise as possible.

Yes, remove the 7805 from the core, and use a short between pin1 and pin3 instead. just like in the drawing (read nr.3 in the list too)

[padjoe.thornton]

Thank you for your help

much appreciated

I'm taking it that even though I'm just using 2 sids and one core, I'll have to add the extra 2 x 2200uf/16v cap, as in

(5) the additional cap at the last SID module reduces high frequency digital noise

Thank You

[m00dawg]

Your SIDs are precious. The C64 PSU is an evil chip destroying piece of shit, to be frank. forum post has some very good information about a modern alternative without having to build your own PSU from scratch. May be something to consider.

[Flemming]

Your SIDs are precious. The C64 PSU is an evil chip destroying piece of shit, to be frank.

Well frank :tongue: i'm not saying you're wrong, but hundreds maybe thousands of people use the C64 brick to power their mbsid. I know there has been a few stories about dudes having their SIDs toasted, but still i think it's a pretty good statistics in the favor of the brick :D

Also keep in mind that there are many revisions of the brick, and some might be better than others.. i can think of 3 different models just on top of my head, and i can say for sure that the brown old model has atleast 3 revisions; one with no fuses, one with 1 fuse and one with 2 fuses. Also iirc some bricks were made in Germany while some were made in asia, which also may have something to do with the build quality, dunno for sure...

So, an old brick with no fuses might be a bad choice, and maybe other bricks can be too. But they are not all bad, atleast to my eyes :wacko:

[m00dawg]

There's more than a "few" stories, but sure it's less than the majority. Thing is, many (all?) of the C64 brick revisions were filled with epoxy. Good luck digging through that mess to replace a fuse. I believe that's what is wrong with one of my bricks.

I was like you, once. But then I had two of those monsters go out on me. One was probably my fault but I'm not digging through mountains of epoxy to replace a fuse. Fortunately, neither have taken my SIDs out (I think one did take a PIC out though but it's been a while since I began refusing to use these things). I figured it would be more repairable to simply build one. The wonderful thing about the Mean Well PSUs (listed in the thread I linked to in my last post) is that, while they are a switching supply, they are way above the audio band (132kHz if memory serves). That's not high enough for those wanting to sample at 192kHz (without capturing some noise), but far above human hearing. For the overly concerned (myself included), using some tantalum and other HF filtering caps may be all that is needed.

The Mean Well isn't completely hobbyless - it's not in a nice plastic case, but a metal one you would typically put inside another case. It's a super solid start though. I would love to see a C64-compatible PSU that was an easy to assemble kit (much like CORE) but that idea, while it has been attempted both on and off these forums, has never really materialized in a "kit". It's not difficult to build, though.

To each his own, of course. I'm sure many have had good luck with the C64 PSUs. I haven't, and many people haven't either. For me, the value of my SIDs vastly exceeds the cost of building or buying a new, modern, PSU. Building PSUs are, in fact, something I find really fun, but again the Mean Well's look pretty dern solid.

[Flemming]

Good luck digging through that mess to replace a fuse.

Hehe, lets try this one more time :)

3 types of PSUs

Now, let's have a look at one of my beige oldskool bricks

See..... no epoxy hell to dig through to replace a fuse! I have one more of these, but it has just 1 replaceable fuse.

I did say 0, 1 or 2 fuses - i know that they all have fuses, but i was kinda talking about 'the outside' since the epoxy issue goes without saying

Fact is, that i can only mention a few booboos where ppl fried their SIDs, though it's still sad i'd say that the C64 psu is a pretty good way to go. Atleast for me, since i am lucky enough to have a PSU that has no problems having it's fuses replaced... you could get one too :)

I was like you, once.

Hehe, so i will get better too, you mean?

I am not saying that your way is not good in any way at all - i'm just saying that it is a bit harsh to proclaim 'every C64 brick to quite frankly be a piece of shit!' since there are many variations of them. It's like saying 'cars are bad' because you once drove a crappy one.

[Flemming]

Hmm, i did forget to add one special story

I have a C64 brick (the white 'striped' one) that outputs WAY more than 9VAC. But i was the cause :logik: i thought "let's try doing things a bit different", the brick made a loud 'bang' and then it was 'game over'... i'm not even sure that a new fuse would save it in any way :) i was pretty thorough about killing it, it seems.

I also want to point out that just because fuses are easily replaceable i don't think that the PSU will rock in any special manner.. but it does give some safety... or at least, a sensation of it :D

[m00dawg]

Ah I see what you mean now. I never knew C64 PSUs even had externally accessible fuses :) I wonder if those are in fewer numbers in the US or if I'm just unlucky. The thing about the safety is the fuse is that it helps my own stupidity. Apart from that I'll admit there isn't much going on a C64 PSU that's different than modern linear PSUs.

However, I'd much prefer new electroyltic caps over ones that have been around for 20 years and that's getting close to the shelf life of some electrolytics. I've run into bad caps on gear less old than many of the C64's out in the wild. I would also guess that failure rates among 20 year old regulators over new ones should be taken into account as well. Again, how much are SIDs worth? More than a 20 year old PSU? For me, the answer is absolutely.

SIDs aren't going to be easier to find, after all; but all the parts found in a C64 PSU are readily available and can be improved upon.