Using a picoPSU: tired of the problems. Please help.

[voyager]

-12v is used in a pc for the serial port, alot of pc's still have one.

[Amiga1992]

Well a lot o fthings have been said in this thread, all different, many weird. Shame about Stedy not posting anymore.

Anyway, here's some more stuff for people to try to figure out:

- Connected the picoPSU to Stedy's adapter.
- Connected the small diskdrive power header of the picoPSU to the disk drive.
- Flicked the switch - IT WORKED

So what the hell?? It's all working now but I have no idea why it behaves this way. The power brick load issue mentioned before seems to be the more plausible one, but why does it work in this way? The power brick is still the same.

[Calgor]

Originally Posted by Akira

FINDINGS
I connected the picoPSU to a CD ROM drive and a disk drive.
When I connect JUSt the CD-ROM drive, it powers up.
When I conect JUST the disk drive, it powers up.

When I connect BOTH, it doens't.

Both picoPSUs act the same way.

MORE FINDINGS

If I hardwire the power witch connector to on an i plug the power into the picopsu, it powers up when connected to the amiga and seems to run normally.

Originally Posted by Akira

- Connected the picoPSU to Stedy's adapter.
- Connected the small diskdrive power header of the picoPSU to the disk drive.
- Flicked the switch - IT WORKED

So what the hell?? It's all working now but I have no idea why it behaves this way. The power brick load issue mentioned before seems to be the more plausible one, but why does it work in this way? The power brick is still the same.

Just a guess, could it be that dodgy wiring or similar is preventing it from turning on with a larger power surge at startup with the amiga connected (which is why it works when the picopsu is already on and hot plugged to the amiga), and Stedy's adapter improves your end to end wiring quality? I have found with dodgy wiring when a larger current is required it is more likely to fail.

Also I had a problem where I had an ATX PSU that needed a load on +5VSB to turn on from standby. And in the quote above you say it works if you hardwire the switch to on. And as you either did not have a load on +5VSB or joined them (which may have tried to draw more watts than +5VSB can handle thereby shutting off or damaging the picoPSU), that could alternatively be a factor? Not sure if Stedy's adapter would put any load on +5VSB or circumvent any PicoPSU damage.

Note that I don't have experience with PicoPSU but I share your pain as I had a PSU that I couldn't get to work properly until 4 years later when I found this undocumented +5VSB minimum load "feature" that not even the manufacturer could tell me about and no other PSUs I have possess

[Amiga1992]

Originally Posted by Calgor

Just a guess, could it be that dodgy wiring or similar is preventing it from turning on with a larger power surge at startup with the amiga connected (which is why it works when the picopsu is already on and hot plugged to the amiga), and Stedy's adapter improves your end to end wiring quality?

I thought at first of that, but all the findings I posted in the message you quoted were done USING Stedy's adapter. The same problems appeared using it or my home made adapter. The same problems happened 3 years ago when I wired the ATX connector straight to my motherboard. And the same happens with two different types of Amiga. Really weird.

It does seem the power supply wants something extra, connecting the floppy drive to the small +/-12V terminal has seemed to fix the problem, everything works normal, picoPSU is not damaged, Amiga is not damaged. If there's an issue is in the power brick, but this is an issue I certainly do not understand. Perhaps everyone that has connected their Amigas to picoPSUs have done so using one of the extra power headers to connect hard drives/ disk drives / etc, and this problem ha snot appeared for them.

[Calgor]

Originally Posted by Akira

I thought at first of that, but all the findings I posted in the message you quoted were done USING Stedy's adapter. The same problems appeared using it or my home made adapter. The same problems happened 3 years ago when I wired the ATX connector straight to my motherboard. And the same happens with two different types of Amiga. Really weird.

It does seem the power supply wants something extra, connecting the floppy drive to the small +/-12V terminal has seemed to fix the problem, everything works normal, picoPSU is not damaged, Amiga is not damaged. If there's an issue is in the power brick, but this is an issue I certainly do not understand. Perhaps everyone that has connected their Amigas to picoPSUs have done so using one of the extra power headers to connect hard drives/ disk drives / etc, and this problem ha snot appeared for them.

Ah sorry I misunderstood with all these adapters.

But if you connect the floppy using the PicoPSU directly, that also means less load is going through the Amiga power connector - which could be an alternative cause of the problem (not sure if you tried with no floppy drive connected) to the mentioned different distributed load on PicoPSU by using its small 12V terminal. Extra load through the Amiga power connector has caused problems for people before, but that is more likely with a high power BPPC card or a bad motherboard.

[Amiga1992]

Yes it seems as a problem of "load on powerup" as mentioned by thgill a page ago... which in case would point towards the culprit being the power brick. The two machines have totally different configurations, the A600 is just bare bones and the A1200 only has a 030, and the picoPSUs are 120W so that's not at all the problem, but it seems the brick can't cope with initial load on powerup.

Your explanation makes a lot of sense, about dividing the load, and could be a temporary solution until I test another brick! Thanks for your opinion.

edit:

[ Show youtube player ]

[Stedy]

Hi,

Christmas and illness have kept me away for a few days.

Covering issues from a few posts...

The picoPSU adaptor draws around 1mA from the +5VSB, that is all the 74HC74 D-type uses in this mode.

@Akira, it sounds like the 120W AC-DC converter used with the picoPSU is suspect. It could be that it needs a minimum load which you do not meet with the Amiga. An A1200 with HDD and accelerator uses around 15W.

I use a 60W mains adaptor with no issues. It would take some time but I could query some of my customers to see what they have. I have sold over 50 picoPSU adaptors and 120+ normal ATX adaptors, in 3 years with no problems, excluding orders lost in the post!

Most ATX power supplies have sense connections for adjusting the output voltage under load, that is why all +5V connections should be connected together. The 3.3V remote sense no load scenario is taken care of by the ATX specification.

@Akira

Are you supplying power to the A1200 via the floppy drive power connector?
If you are this will damage the A1200. Always use either the original power cable or solder wires to the underside of the motherboard to the correct power pins.

Do you have a working, regular ATX power supply you could borrow?
Second hand tested ATX PSUs can be bought for a few pounds. You could uses this as an alternate +12V supply.

I test all the ATX adaptors I make with a 350W ATX PSU and with no load it powers up and the correct voltages are seen on all outputs. The same happens with the picoPSU. I don't test every adaptor with the picoPSU as it is fragile compared to an ATX PSU connector.

Ian

[Amiga1992]

Oh man I hope you are recovered, Merry Christmas!

Originally Posted by Stedy

@Akira, it sounds like the 120W AC-DC converter used with the picoPSU is suspect. It could be that it needs a minimum load which you do not meet with the Amiga. An A1200 with HDD and accelerator uses around 15W.

Sounds weird, I have a 1200 with a 030@50, scandoubler and a CF-IDE. I guess it doesn't consume that much though.

Are you supplying power to the A1200 via the floppy drive power connector?

NO, never, that would be stupid. I am using your adapter as intended. Or sort of :P Check this picture, shows the cable going into your adapter:



What I did change was to connect the -floppy drive- straight to the PSU instead of to the motherboard connector. That makes the picoPSU work on the flick of the switch.

Do you have a working, regular ATX power supply you could borrow?

I'd have to check but I am not spending any more money in this issue, not even on a spare atx psu. I already bought the adapters, a regular Amiga power supply and other things to try to see if this worked at all or if my Amigas were broken or whatever. I'll see if any friend has one, but to me thi sissue is kind of resolved even though I am still puzzled.

I test all the ATX adaptors I make with a 350W ATX PSU and with no load it powers up and the correct voltages are seen on all outputs.

Your adapters are fine and everything seems fine except maybe the power brick.

I do HAVE to buy another one for my A600 so maybe I should poll in these very boards to see what AC adapters people are using.

I thank you so much for your help throughout this! And for your work on your adapters.

[orange]

perhaps wires are too long.

[Amiga1992]

They are shorter than those found in an ATX PSU.

[Methanoid]

Question for the experts?: Does the Pico need to be connected to an ATX board or could I just plug the 12v into PiCo and extract 5v/12v as needed from the molex connector?

Wondering about fitting a Pico inside an old Atari 520ST (the small case early model with external PSU), soldering to the inside of the power connector and possibly to an A600/1200 as well

[Amiga1992]

Don't take my word completely for it, but I think this is possible. You'll still need the ATX plug, to connect a power switch to it (or connect the switch some other way to the ATX pins), but as long as you put a load on those 5V/12V lines, it should start. read what I had to do above to make the picoPSU start.

[robinsonb5]

Originally Posted by Methanoid

Question for the experts?: Does the Pico need to be connected to an ATX board or could I just plug the 12v into PiCo and extract 5v/12v as needed from the molex connector?

You have to take care of the "PS On" signal on the ATX connector (a toggle switch between that and ground works nicely), but other than that you can take voltages as you please. (in theory!)

I've had an NEC XR385 WaveBlaster MIDI card running from a PicoPSU like that (the PicoPSU was just a convenient way to get the necessary split 12v rails for audio as well as 5v for logic.)

[dJOS]

I made things very simple for myself and bought one of Ian's great little adapters:

http://www.ianstedman.co.uk/Amiga/de...x_adaptor.html

I did however manage to break my pico psu (I think i shorted it out or something by accident) but it still works perfectly with a 250w ATX PSU.

[Methanoid]

Thanks, I forgot about Ian's adapters. Bought 2 (one for ST and one for Amiga)... Now for some Picos

[theshinyknight]

sorry to rez this old thread, but I have one picopsu and I noticed that the issue described by the OP is happening because of loads expectations on the various rails.

I have one myself, and I have no problems turning it on, as long as there is something else attached, other than the amiga...if I plug just the amiga, I get 70% of the time no power (while it power up if the amiga is not connected).

Other weird issues are that the video goes on and off at random, or the hard drive just power down with no reason (I don't think that old IDE drives and CD rom drives has a power saving setting under Amiga)....they just die on me at random, and if I power off and on the picoPSU they just work again normally, without any issue.

I suspect that these adapter are made to power boards that are more powerful than an Amiga...a modern micro ATX probably sucks more power than a whole amiga with CF card, accelerator board, flicker fixed, cd and lan card; so the PSU are made in a way to somehow sense the load and act accordingly.

If you ask me it is dumb, but I do not have a degree in electronic engineering to understand the security implications about these behaviors

Glad that you resolved your issue!

[BrenMcGuire]

Sorry for pulling up this old thread, but I had nearly the same problem and solved it.

I used the Stedmans ATX Adapter with an 80W PicoPSU (from Amazon) in a black Commodore PSU Case. I soldered the Switch to the destinated contacts but got the problem, that I cannot use the switch correctly.

12V plugged in and switch is off: I cannot switch the AMIGA on but switching off works well

12V plugged in and switch is on: The AMIGA starts booting, can be switched off but NOT switched on again. Strange!



After some days trying and mailing with Stedman (Thanks, Mate!) I tried to connect a floppy drive tot he drive-power cables oft he picoPSU. And now? Everything worked fine!

So it seems that this PicoPSU awaits some power consumption on the drive cables. I tried to connect the drive cable tot he AMIGA Power Cable too but this doesnt helped very much.

It was the same before: AMIGA cannot switched on, but switching off works well.



So I ordered a new picoPSU from Amazon with 90W and one with 120W. The main difference except the Watt-Power was that these picoPSU have the drive cables with a connector to the PSU Mainboard (not soldered to the picoPSU).

With these PSUs everything worked fine. I can switch on and off, its like a dream!

I even recognized that the „old, not working well“ PSUs handled the power differently tot he new ones. Everytime I plugged the 12V cable into the PSU the AMIGA LEDs were flashing up for a small moment. This dont happen with the new PSU.

So I returned the old picoPSU and I am happy to get this to an end.

[scu98rkr]

I would really like to be able to buy a new power supply for my amiga off the shelf preferably something smaller than the brick.

[Amiga1992]

Originally Posted by BrenMcGuire

Sorry for pulling up this old thread, but I had nearly the same problem and solved it.

Pulling up old threads is good, and I am glad you figured it out.
I still am using that old picoPSU and have to connect the plug to the floppy drive as described here.

[BrenMcGuire]

Originally Posted by Akira

Pulling up old threads is good, and I am glad you figured it out.

I still am using that old picoPSU and have to connect the plug to the floppy drive as described here.

Thanks! Maybe you should give a new PicoPSU a try?

Originally Posted by scu98rkr

I would really like to be able to buy a new power supply for my amiga off the shelf preferably something smaller than the brick.

Do. you know the 3D Printed case for PicoPSU. This is really awesome!

http://www.thingiverse.com/thing:1794271