Adaptor for picoPSU

[Solo761]

Hi all, I've been thinking about making a power supply by using a picuPSU to power my Amiga(s). Original PSUs are old (no surprise here) so I don't trust them much, and I'm not sure if recapping them (PSUs, Amigas are recapped) would increase their reliability.

Currently I use an ATX PSU, but it's kinda clunky, plus there's a bunch of wires since I didn't cut off anything but just made an adaptor for ATX connector. PicoPSUs are not that hard to find, what is is 12V PSU to feed the power to it. I've been looking at LED PSU's like this one. There are both stronger and weaker ones. My Amigas don't have any power hungry addons so this 80W should be enough. I think it's even small enough to be fitted in original Amiga PSU along with picoPSU. I even have one A500 PSU that's kaputt, I don't know what's wrong with it, got it that way, no burned out components, so I was thinking of gutting it and putting this and picoPSU inside.

Has anyone used PSU like this LED one? I'm worried it's output may not be too "nice", it's made for powering LEDs and they're way more tolerant if it fluctuates a bit than a computer is. Alternative would be to classic 12V brick, but it's kinda "funny" to use brick for another brick . I know some people install picoPSUs in their amigas, but I don't want to cut the case, plus if it's set up inside normal PSU it can be used with any Amiga, not just the one it's installed in.

[alexh]

I would imagine you could take apart a classic 14v PicoPSU brick and fit it internally together with the PicoPSU into an A500 brick.

I like the idea. Modern replacement internals for Amiga brick.

I wonder if every brick has the internal shape / screw holes?

I'm pretty sure there are at least three different bricks, A500 heavy, A500 feather and A1200.

[Solo761]

Problem with classic bricks is that bricks themselves are glued. I believe you could open one with something like dremel, but it would be rather risky bussines. If you cut the goods inside it could be all for nothing.

Of course, that's always an option, it wouldn't be the craziest thing to do . It's only that this metallic one looks more practical, if it's reliable. Only old electronics board would need to go out, every cable could be reused. From the outside it would look like an original .

I don't have A500 heavy brick so I can't tell how it looks inside, but A500 light and A1200 are the same shape/screw hole wise.

A500
A1200

[demolition]

I had a dead PSU in an almost mint chassis, so I made this one for my Amigas:
http://eab.abime.net/showthread.php?t=70315

Working great so far, and about twice as powerful as a regular PSU, so should be able to power even a heavily expanded A1200.

[Solo761]

Well, that's about the idea, we could name it lego principle, brick inside a brick .

I have to find dimensions of that LED PSU, bigger ones have them written in specification, but, by Murphy's law, this one doesn't. It looks ok, but looks can be deceiving. If/when I dig them out and it fits inside Amiga PSU I'll probably bite the bullet and order one.

[Solo761]

I finally did this today. I have two A500 PSUs that are just clicking when I turn them on so there are plenty of cases .

It works, although I'm not that thrilled. I tested it with A600 that I usually use with it's own original PSU. Compared to original one, A600 with this PSU has noisy picture. It seems 5V line has some noise.

I guess it's picoPSU's fault, it's $25 one from ebay, not original one. It's either that or maybe method I used to connect wires. I used block terminals to connect wires instead of soldering. But I doubt it could create that much noise.

Why can't something be easy?

[demolition]

Sounds like it is probably due to it being of poor quality. I have not noticed any noise in the picture with my PicoPSU mod, but mine is the original one.

[amigoun]

I can confirm high noise in picture with some pico psu clone included in particular mini-itx Eurocase case when using with amiga. Some Pico PSUs (clones) are really low quallity ones.

[Solo761]

It's this one

http://i.imgur.com/qZGArvM.jpg
http://i.imgur.com/8bi7ft2.jpg

So if anyone wants to do this themselves this is one to avoid. I may order another, different, one. But first I have to google if there are some picoPSU clones review. "Problem" with original ones are that most sellers I've found are in USA so shipping alone costs more than this clone :/

[Solo761]

After some time I came to the conclusion that it depends heavily on AC adapter that's used with PicoPSU. Today I've tried 12V adapter from my HTPC (it's marked as st-c-075-12000500ct, from googling I've found it's replacement brick for laptops) and those two clone PicoPSU's are noise free, picture is perfectly clear if I use this brick.

I've bought two more PicoPSU's in the meantime, another clone (different) and original one, and both of them had noise if I used them with first brick. It was a bit better but that could also be my imagination.

Biggest problem now is where to find quality 12V 5A (or more) bricks. These cheap chinese ones aren't reliable (yesterday one blew, luckily A500 is undamaged). I've looked on ebay for the one from my HTPC and there are similar ones, laptop replacement bricks (I'm not sure what 075 means but 12000 is 12V and 500 is 5A, there are similar st-c-075-18500350 which are 18.5V 3.5A).

Also, it seems they have problems with -12V rail. Original one had -5V instead of -12V, same as one of those first two clones. Sound on Amiga is of course garbled. The other two clones are fine, they have -12V there.
I'm not sure if original one was that way from the beginning or it got that way after the "mishap". When experimenting I have my Amigas connected only to monitor, when I noticed this I tried plugging the speakers and confirmed there's a problem with -12V.

[Arnie]

I use a PicoPSU (60w) with Steady's adapter and a cheapo 12v laptop supply, works well so far, no problems.

I use it in my CDTV but you could easily fit it inside an Amiga power brick.

I bought the PicoPSU & Power Supply together as a package.

[Solo761]

The one that turned out the best is also cheap, nothing extraordinare. I've found similar one on ebay

http://www.ebay.co.uk/itm/190873647610

At least according to picture. Only difference is that it has two prong AC connector, mine has three prong. I guess that's what 5 in st-c-075-12000500ct means, the one from above is 070.

The one that crapped out was also from ebay, it cost about $9, shipping included.

[Amiga1992]

I also can confirm different results with different PSU bricks.

As a rule of thumb: try to spend the extra few bucks to get both an ORIGINAL picoPSU and one of those bundles which come with a power brick that is guaranteed to work with it. Yes, you spend some more moollah, but the end result is that the setup will be more reliable.

[Solo761]

I went with clones because most original ones are from USA and they have really pricey shipping so it's usually more than the item itself :/.

After three types I've tried (two clones and one original) I would say it's not such a difference, it's the brick that makes all the difference. And that makes it even worse because there is a flood of low quality ones even for high prices.

[Amiga1992]

Yeah I know what you mean, I bought mine from USA, but the clones I bought sometimes even came already broken and shit. I just don't trust them.

Even with the originals, the difference on power bricks was important. With my current picoPSUs on my two Amigas, if I change the power supplies around, I get RIDICULOUS distortion on sound and maybe video problems. I have an older picoPSU and a newish one, so they are probably different.

So you are definitely right about the importance of the brick being the adequate one!
Usually the packs you buy with picoPSU+power brick have been tested on that particular config and should work fine, but you shouldn't exchange them with others.

[demolition]

I got the original one from USA with the PSU in a bundle, but only because I had a friend living over there who could bring the package back to me, otherwise it would have been very expensive. I have not had any issues with it at all. No audio or video noise or instability of any kind.

Remember that the PicoPSU doesn't do anything to the 12V - it just passes it through, so if the 12V PSU is noisy, it will go straight into the Amiga and its audio parts. If I had a problematic 12V PSU, I would probably try shortening the 12V cable. If they used too thin wires, the voltage drop would be too high for it to work properly and maybe the inverter creating -12V would send noise spikes back onto the 12V line.
Alternatively, one could add a 25V low ESR electrolytic capacitor on the PicoPSU input to lower the noise.

[jezry]

I have made a couple of replacement bricks out of the psu from old dvds works great.

[Amiga1992]

Originally Posted by demolition

Remember that the PicoPSU doesn't do anything to the 12V - it just passes it through, so if the 12V PSU is noisy, it will go straight into the Amiga and its audio parts.

I had no idea of this. That's a great thing to know!!!

[Solo761]

Interesting and good to know, although I had issues with screen. Depending on brick used there was grain and/or stripes floating across the screen. Luckily I unexpectedly found one that is "grain free".

I have sound issue only with two PicoPSU (one clone and one original) that have flaky -12V rail.