ATX Power supply conversions?

bugsymalone666 · 06 March 2017, 14:56

So in another thread I built a lovely retro looking device to go with my Amiga, alas its failed rather quickly!

The device originally was a Dynatek Magneto optical disc drive unit with its own PSU inside, the drive was huge and probably needed a fair amount of power, I installed a Scsi CD rom (that I cant get to work yet) and a Gotek/HXC unit. The other day I started suffering problems with even the HXC working so I wondered if the old power supply was giving up the ghost, seemingly I think it has (not clean power and pulsing) luckily I had a 500w ATX PSU laying about which seems to work find but doesnt fit in the case, so I thought about hunting down another that would and wondered about doing a PSU conversion for my whole Amiga setup.

At present I have 2 original amiga box PSUs, one for the A500 and one for an A590 with a 1gb disc in, I thought if I could run the whole lot off the retro unit if I put an ATX psu inside and then soldered on 2 Amiga power connectors.

Looking at the OG amiga PSUs they look to be about 74w each, from experience, what do people use? any issues to look out for other than lovely clean power from a new PSU lol

idrougge · 06 March 2017, 15:27

Some people use small ATX PSUs, some use picoPSU ATX PSUs, and some use Meanwell industrial PSUs.

Mind you, you could also go for a capacitor refurbishment in your old Commodore PSUs and just replace the old one in your external cabinet with something sufficiently modern from Meanwell or some other supplier for hobbyists and industry.

bugsymalone666 · 06 March 2017, 18:44

Theres nothing really wrong with the Commodore PSU units aside from looking tired, I guess its more that I have 3 pieces of equipment, 2 of which are connected together (A500 and A590) and have so much extra stuff to turn on, when having 1 unit for all 3 would make sense as one on switch. It would also mean that all grounds are from one power supply as I did wonder if that could cause some issues.

Pat the Cat · 06 March 2017, 19:46

Rare for that to happen. I once cased up 4 different PSUs for a dual Amiga setup... Only place the Amigas directly connected was the video grounds to a video mixer.

Didn't have any problems, putting the whole lot in one metal box solved a bunch of issues.

Having separate power switches made it very easy to shut down and restart one system while the other was generating visuals.

Only downside from your point of view was physical size - you want the whole thing in one box. Dedicated PSU with one switch and separate Amiga power connectors seems quite sensible approach for what you are doing.

bugsymalone666 · 06 March 2017, 19:53

well I have ordered a 250w atx psu(£6.50 on ebay

), as I think it will just fit in my case, based on how each commodore PSU is 74w, taking into account aside from that 150w, I only need to power a CD rom and a HXC I think it should be fine, then just one on switch/plug!

idrougge · 06 March 2017, 20:36

Some things to consider:
1. ATX PSUs are often of awful quality and may sooner or later give up and damage your Amiga.
2. Modern ATX PSUs tend to use 12 V as their main rail, since that is what modern PCs pull most of their current from. The Amiga pulls most of its current from the 5 V rail, which may lead to an unstable power source since the PSU isn't loaded the way it was intended to.

bugsymalone666 · 07 March 2017, 20:20

Quote:

Originally Posted by idrougge

Some things to consider:
1. ATX PSUs are often of awful quality and may sooner or later give up and damage your Amiga.
2. Modern ATX PSUs tend to use 12 V as their main rail, since that is what modern PCs pull most of their current from. The Amiga pulls most of its current from the 5 V rail, which may lead to an unstable power source since the PSU isn't loaded the way it was intended to.

Yeah some new cheap PSU units can be rubbish! I would probably say because the one I have bought is a unique size, its not one of the standard mass produced units so may suffer a little less from build quality issues.

As for the 12v rail vs 5v Rail thing, I dont think that'll be a problem, the amiga+A590 is rated 6a from the 5v rail and about 2a from the 12v rail, the new ATX psu has a 16a 5v rail and a 14a 12v rail.

It would have been nice to make new leads, but from what I understand the square amiga 500 connectors are obsolete?

Daedalus · 07 March 2017, 20:32

The problem with the rails is not the maximum capacity but the minimum current required for regulation. Without the minimum draw, some PSUs will have trouble regulating all their rails. A dummy load can be added easily consisting of a high wattage resistor, the specifications of which can easily be calculated if you know the minimum draw required for stable operation.

Pat the Cat · 07 March 2017, 20:54

Quote:

Originally Posted by Daedalus

The problem with the rails is not the maximum capacity but the minimum current required for regulation. Without the minimum draw, some PSUs will have trouble regulating all their rails. A dummy load can be added easily consisting of a high wattage resistor, the specifications of which can easily be calculated if you know the minimum draw required for stable operation.

Very true. Some of the smarter ATX PSUs have that sort of sensing circuitry because they were designed for gaming PCs with 2 graphics cards. A specific example would be the UK version of the Hyper-X (not the US version).

Tried it with a regular office desktop, not enough current demanded to even turn on. Beautiful tech, lovely engineering, but sadly needs fooling to get to work with a lot of systems.

The eBay cheapies are best avoided too, in my experience. Too hit and miss. A 2nd hand ATX from a local dealer is maybe the most reliable way to get something usable.

idrougge · 08 March 2017, 10:36

Quote:

Originally Posted by bugsymalone666

Yeah some new cheap PSU units can be rubbish! I would probably say because the one I have bought is a unique size, its not one of the standard mass produced units so may suffer a little less from build quality issues.

That depends. I was going to repurpose two old small ATX PSUs and both had leaking caps. Granted, they were from the age when caps leaked all over the place (early 2000s).

Quote:

Originally Posted by bugsymalone666

As for the 12v rail vs 5v Rail thing, I dont think that'll be a problem, the amiga+A590 is rated 6a from the 5v rail and about 2a from the 12v rail, the new ATX psu has a 16a 5v rail and a 14a 12v rail.

That's the thing. 16*5 is less than 14*12. Which means that the main rail is 12 V.

Quote:

Originally Posted by bugsymalone666

It would have been nice to make new leads, but from what I understand the square amiga 500 connectors are obsolete?

Indeed they are. They make D-sub 23 connectors seem commonplace.

bugsymalone666 · 09 March 2017, 14:27

Quote:

Originally Posted by idrougge

That depends. I was going to repurpose two old small ATX PSUs and both had leaking caps. Granted, they were from the age when caps leaked all over the place (early 2000s).

That's the thing. 16*5 is less than 14*12. Which means that the main rail is 12 V.

Indeed they are. They make D-sub 23 connectors seem commonplace.

Quite! :
http://www.ebay.co.uk/itm/3904155651...%3AMEBIDX%3AIT

Well the new PSU has arrived today so I'll see what happens!

thgill · 09 March 2017, 16:40

In case you are interested in rebuilding your A500 PSU, I have used the 65 watt Meanwell PT-65B PSU on a couple different occasions. Under $20, lots of 5v current and cool running.

http://www.mouser.com/ProductDetail/...2bT2RNJA%3D%3D

I have been using one for about 4 years now. Rock solid powering everything from a stock A500 to a Vampire 2 powered A600 to an Blizzard 1260 A1200.

Here is one I finished a couple days ago:

2 things to note: It doesn't line up with the original pcb post mounts. So you will have to DIY some standoffs/mounts for it. And the fit between the case posts is tight, so they have to be shaved down a bit. Otherwise looks completely stock from the outside.

drusso66 · 22 March 2017, 23:41

Quote:

Originally Posted by thgill

In case you are interested in rebuilding your A500 PSU, I have used the 65 watt Meanwell PT-65B PSU on a couple different occasions. Under $20, lots of 5v current and cool running.

http://www.mouser.com/ProductDetail/...2bT2RNJA%3D%3D

I have been using one for about 4 years now. Rock solid powering everything from a stock A500 to a Vampire 2 powered A600 to an Blizzard 1260 A1200.

Here is one I finished a couple days ago:

2 things to note: It doesn't line up with the original pcb post mounts. So you will have to DIY some standoffs/mounts for it. And the fit between the case posts is tight, so they have to be shaved down a bit. Otherwise looks completely stock from the outside.

Is this easy to install any guides available for wiring one of these.

idrougge · 23 March 2017, 00:34

If you can't handle the quote button, you should stay away from electrical installations.

drusso66 · 23 March 2017, 20:50

Quote:

Originally Posted by idrougge

If you can't handle the quote button, you should stay away from electrical installations.

Thanks for sarcasm, but for your information I work in construction industry with electrical installations on a bigger scale than a PSU, I was just looking for advice.
The fact that I am not a wizard like you at using the forums should not matter.

E-Penguin · 25 March 2017, 10:33

There's a mounting bracket for 3d printing here:
https://www.thingiverse.com/thing:2202528

E-Penguin · 30 March 2017, 13:21

Quote:

Originally Posted by thgill

In case you are interested in rebuilding your A500 PSU, I have used the 65 watt Meanwell PT-65B PSU on a couple different occasions. Under $20, lots of 5v current and cool running.

Do you have a source for the Molex connectors for the PT-65B?

The datasheet says Molex 5277-02 & 5273-06 but I can't find a source that'll sell them for a reasonable price individually.

Daedalus · 30 March 2017, 14:25

Here is a complete connector kit for both connector shells and crimps for £6.72+VAT and delivery.

thgill · 30 March 2017, 14:36

Quote:

Originally Posted by E-Penguin

Do you have a source for the Molex connectors for the PT-65B?

The datasheet says Molex 5277-02 & 5273-06 but I can't find a source that'll sell them for a reasonable price individually.

In all honestly I solder straight to the pins on the built in connector.

I've never bought the molex connectors for them.

E-Penguin · 30 March 2017, 22:12

Damn postage is more than the connectors. Soldering to the pins starts to sound attractive...

06 March 2017, 14:56	#1
bugsymalone666 Amiga baby yeah! Join Date: Nov 2014 Location: Basingstoke Posts: 108	ATX Power supply conversions? So in another thread I built a lovely retro looking device to go with my Amiga, alas its failed rather quickly! The device originally was a Dynatek Magneto optical disc drive unit with its own PSU inside, the drive was huge and probably needed a fair amount of power, I installed a Scsi CD rom (that I cant get to work yet) and a Gotek/HXC unit. The other day I started suffering problems with even the HXC working so I wondered if the old power supply was giving up the ghost, seemingly I think it has (not clean power and pulsing) luckily I had a 500w ATX PSU laying about which seems to work find but doesnt fit in the case, so I thought about hunting down another that would and wondered about doing a PSU conversion for my whole Amiga setup. At present I have 2 original amiga box PSUs, one for the A500 and one for an A590 with a 1gb disc in, I thought if I could run the whole lot off the retro unit if I put an ATX psu inside and then soldered on 2 Amiga power connectors. Looking at the OG amiga PSUs they look to be about 74w each, from experience, what do people use? any issues to look out for other than lovely clean power from a new PSU lol

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
ATX Power Supply for A4000T	Calgor	support.Hardware	17	06 October 2018 13:52
FS: ATX power supply setup for Amiga	shuttlepilot	MarketPlace	3	21 July 2015 18:01
ATX power supply and Amiga 1200	HardStep	support.Hardware	5	02 February 2006 21:06

06 March 2017, 15:27	#2
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	Some people use small ATX PSUs, some use picoPSU ATX PSUs, and some use Meanwell industrial PSUs. Mind you, you could also go for a capacitor refurbishment in your old Commodore PSUs and just replace the old one in your external cabinet with something sufficiently modern from Meanwell or some other supplier for hobbyists and industry.

06 March 2017, 18:44	#3
bugsymalone666 Amiga baby yeah! Join Date: Nov 2014 Location: Basingstoke Posts: 108	Theres nothing really wrong with the Commodore PSU units aside from looking tired, I guess its more that I have 3 pieces of equipment, 2 of which are connected together (A500 and A590) and have so much extra stuff to turn on, when having 1 unit for all 3 would make sense as one on switch. It would also mean that all grounds are from one power supply as I did wonder if that could cause some issues.

06 March 2017, 19:46	#4
Pat the Cat Banned Join Date: Dec 2016 Location: Nottingham, UK Posts: 481	Rare for that to happen. I once cased up 4 different PSUs for a dual Amiga setup... Only place the Amigas directly connected was the video grounds to a video mixer. Didn't have any problems, putting the whole lot in one metal box solved a bunch of issues. Having separate power switches made it very easy to shut down and restart one system while the other was generating visuals. Only downside from your point of view was physical size - you want the whole thing in one box. Dedicated PSU with one switch and separate Amiga power connectors seems quite sensible approach for what you are doing.

06 March 2017, 19:53	#5
bugsymalone666 Amiga baby yeah! Join Date: Nov 2014 Location: Basingstoke Posts: 108	well I have ordered a 250w atx psu(£6.50 on ebay ), as I think it will just fit in my case, based on how each commodore PSU is 74w, taking into account aside from that 150w, I only need to power a CD rom and a HXC I think it should be fine, then just one on switch/plug!

06 March 2017, 20:36	#6
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	Some things to consider: 1. ATX PSUs are often of awful quality and may sooner or later give up and damage your Amiga. 2. Modern ATX PSUs tend to use 12 V as their main rail, since that is what modern PCs pull most of their current from. The Amiga pulls most of its current from the 5 V rail, which may lead to an unstable power source since the PSU isn't loaded the way it was intended to.

07 March 2017, 20:32	#8
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	The problem with the rails is not the maximum capacity but the minimum current required for regulation. Without the minimum draw, some PSUs will have trouble regulating all their rails. A dummy load can be added easily consisting of a high wattage resistor, the specifications of which can easily be calculated if you know the minimum draw required for stable operation.

09 March 2017, 16:40	#12
thgill Registered User Join Date: May 2008 Location: Mason, Ohio / USA Age: 48 Posts: 391	In case you are interested in rebuilding your A500 PSU, I have used the 65 watt Meanwell PT-65B PSU on a couple different occasions. Under $20, lots of 5v current and cool running. http://www.mouser.com/ProductDetail/...2bT2RNJA%3D%3D I have been using one for about 4 years now. Rock solid powering everything from a stock A500 to a Vampire 2 powered A600 to an Blizzard 1260 A1200. Here is one I finished a couple days ago: 2 things to note: It doesn't line up with the original pcb post mounts. So you will have to DIY some standoffs/mounts for it. And the fit between the case posts is tight, so they have to be shaved down a bit. Otherwise looks completely stock from the outside.

23 March 2017, 00:34	#14
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	If you can't handle the quote button, you should stay away from electrical installations.

25 March 2017, 10:33	#16
E-Penguin Banana Join Date: Jul 2016 Location: Darmstadt Posts: 1,213	There's a mounting bracket for 3d printing here: https://www.thingiverse.com/thing:2202528

30 March 2017, 14:25	#18
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Here is a complete connector kit for both connector shells and crimps for £6.72+VAT and delivery.

30 March 2017, 22:12	#20
E-Penguin Banana Join Date: Jul 2016 Location: Darmstadt Posts: 1,213	Damn postage is more than the connectors. Soldering to the pins starts to sound attractive...

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)