520ST PSU Remake

[rubber_jonnie]

I got a 520ST from exxos a little while ago, unfortunately, it came without an external PSU, so I have been using a Meanwell type PSU with a Pico PSU and a breakout board.

This is all a bit unsatisfactory though as there are all sorts of bits floating around and making my workbench cluttered.

An internal PSU would be possible with a Pico, but I want to keep it external since it already has a SIMM adapter installed internally and it's a bit cramped inside.

So I'm going to build a whole new PSU for it, and I'll document it here so anybody else who wants to do the same will have a complete parts list, including a 3d printed case, to work from.

More to follow soon....

[exxos]

Sounds good.

I did consider a external one a few years ago, even got the case and piles of various connectors. It was one which could power the ST, 2 floppy drives and have a jack to power ultrasatan etc. Though with all the work involved I speculated it would end up costing £150-£200 to build There was a lot of work in drilling the holes for the connectors, screw holes, getting it all aligned up, doing all the wiring etc, it wasn't a simple job

Things be a lot better with a 3D printed case, as the holes can be done easily. So its just a matter of the wiring more than anything. So be interesting to see what you come up with

[rubber_jonnie]

Somebody has already designed a case, so that's good for one thing. I will put together a parts list so folks can get an idea of cost, but it should come in at about £50-£60 total.

It isn't cheap, but I thought it would be good to get all the info in one place for people who want to do it, and of course you could potentially use it for other things.

[exxos]

Sounds good to me, I need a PSU for my ST!

[rubber_jonnie]

Sounds good to me, I need a PSU for my ST!

Better get it done ASAP then!

[rubber_jonnie]

Ok, so here is a provisional parts list with a list of prices I've paid, and where the parts came from. There will be a few bits that I will add later.

I hope to have all the parts this week, and I'll add in anything that's missing as I find I need it.

1. Meanwell PT65-B. This PSU has 5v @ 5.5A, +12v @ 2.5A and -12v @ .5A outputs with 5v adjustment, so is well suited for the job in hand. Cost was £26.75 including VAT and next day delivery. You can buy it here: https://www.powersuppliesonline.co.uk/p ... upply.html

2. For cable connection you will need 2 and 6 pin Molex SPOX 5195 connectors. The part numbers from RS are 670-5183 and 670-5168 respectively. After doing some digging, most places only seem to sell them in minimum numbers. Total cost of the order was £12.10 including VAT and delivery was free. RS can be found here: https://uk.rs-online.com

3. For some reason, the connectors don't come with contacts, but once again there is a minimum order, this time of 100. I got mine from eBay instead here: https://www.ebay.co.uk/itm/MOLEX-08-70- ... 2749.l2649, where I was able to find 10 for £4 with free delivery.

4. Casework. I will be 3d printing the case based on this design: https://www.thingiverse.com/thing:2701695. The designer has done a great job of designing this specifically around our chosen PSU, and has also supplied a design without the Amiga logo so we can all sleep soundly in the knowledge that we won't be tainted

BTW, print time for each half of the case is a good 7+ hours, so be prepared.

The remaining parts are relatively minor, such as cable strain relief, cable, power plug and on/off switch.

I'm not 100% sure I will go for a power switch, but I will cover that in the build process once I get going.

I'll post more as I get going.

[exxos]

Looking forward to seeing how it pans out. The 3D files look nice.. though 7 hours...

I wonder if a "off the shelf" ABS "vented box" could be used instead ? I mean worst case is 3D print some funky spacers for mounting it as the case will likely be inconvenient dimensions...

[rubber_jonnie]

Looking forward to seeing how it pans out. The 3D files look nice.. though 7 hours...

I wonder if a "off the shelf" ABS "vented box" could be used instead ? I mean worst case is 3D print some funky spacers for mounting it as the case will likely be inconvenient dimensions...

An off the shelf box could probably be used, but I will have a go at the 3d printed box, as it's such a nice job. If I run into any problems printing it, I may need to revisit, but I guess we'll see.

It would be possible to reduce the print time I expect, by using different infill/print speeds etc, but I have found nice settings for my own printer, and using those it's 7 hours.

I did have a conversation with Icky about an Atari FDD PSU, which looked perfect, but unfortunately the case is a little bit too small.

More parts coming today I hope so I just need to find a window in which to print the casework, though it shouldn't stop me from assembling and testing the PSU and associated cables.

[tzok]

Good replacement is also an Astec AA21430 (it was used in CISCO 1800 series routers). Connector is a regular DIN-7F. Same cable fits also SF3x4 floppy drives (despite they use DIN-5 and don't have -12V line).

[rubber_jonnie]

Good replacement is also an Astec AA21430 (it was used in CISCO 1800 series routers). Connector is a regular DIN-7F. Same cable fits also SF3x4 floppy drives (despite they use DIN-5 and don't have -12V line).

I'm not familiar with that PSU, which I'm sure is eminently suitable, but my plan was to completely recreate a new PSU from scratch that anybody could get the parts for new, and document the process.

I guess we'll see how it turns out!

As long as there's no magic smoke in my future, I'll be happy.