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Is it possible to power a QL board with a ATX PSU?
Posted: Tue Jul 14, 2015 9:59 am
by vanpeebles
An interesting potential project popped up this morning. Is it possible to power a QL mobo using an ATX PSU with out having to use a backplane? 5v mod needed for regulator etc?
Re: Is it possible to power a QL board with a ATX PSU?
Posted: Tue Jul 14, 2015 10:50 am
by tofro
Peter,
Possible? Yes
Piece of cake to build? Probably not.
Modifications that would be needed in the QL:
Remove the 5V regulator, feed 5V directly to the QL board
Remove the +/- 12V regulators, inject current directly at their output feeds.
Note ATX PSUs need to be switched on by grounding their PSU ON line (That's the green cable, typically pin 14 or 16 on the larger plug.
Also note you shouldn't try and switch on an ATX PSU without sufficient load on the outputs - Most probably it wouldn't start up at all, worst case it can be damaged.
Tobias
Re: Is it possible to power a QL board with a ATX PSU?
Posted: Tue Jul 14, 2015 11:01 am
by vanpeebles
Ah so probably best holding on for another backplane of some sort? I've acquired an interesting rack mount case which has a small ATX psu inside, the PSU actually has a proper separate rocker switch which is hardwired into the PSU on separate leads. It has no molex connectors though, just the motherboard connector.
Re: Is it possible to power a QL board with a ATX PSU?
Posted: Tue Jul 14, 2015 11:28 am
by Derek_Stewart
Hi,
Direct connection of a PC ATX PSU, is not that hard, but would mean direct connection of the -12v from the ATX supply to the QL board.
A Backplane, i.e. Qplane or Mplane is the best route.
I have a Qplane, which maybe could be reproduced, with regards to the Mplane, they were given to Dave in the USA.
Re: Is it possible to power a QL board with a ATX PSU?
Posted: Tue Jul 14, 2015 11:42 am
by vanpeebles
We could do with some new backplanes
I was hoping to fit a QL mobo with the QLSD and maybe see if I could fit a rgb2vga board inside too.
Re: Is it possible to power a QL board with a ATX PSU?
Posted: Tue Jul 14, 2015 11:56 am
by Derek_Stewart
vanpeebles wrote:We could do with some new backplanes
I was hoping to fit a QL mobo with the QLSD and maybe see if I could fit a rgb2vga board inside too.
Hi,
You could try removing the QL Heat Sink and Power regulator and fit a DC-DC converter, which I have done with one of my QLs. This will give you more space.
Is the RGB2VGA converter a GBS8200... which a single VGA output.
Re: Is it possible to power a QL board with a ATX PSU?
Posted: Tue Jul 14, 2015 12:18 pm
by vanpeebles
I should be ok for space I think. I'll have to have a mockup with a scrap ql mobo I have
Yep it's a gbs 8220 I think. Would be nice to have everything all internal and powered.
Re: Is it possible to power a QL board with a ATX PSU?
Posted: Thu Jul 16, 2015 11:37 pm
by Dave
I do have a bunch of Mplanes, and as I've said elsewhere, I'll be resuming QL activities in September most likely. I do have a 4-layer PCB design for a QL backplane that has ATX power, but I will not be producing it. I will probably release the design files in September or October.