As a project, that sound like a nice challenge. Economically however, I don't think it's feasible. It's must cheaper in terms of both time and money to just buy a used one, do a recap and swap the fan.

Well, i always loved electronics but i never got into any actual projects. I gained a huge amount of interest lately and began collecting money to invest into some electronic tools such as an base soldering station with hot air pistol and an oscilloscope.
I finished high school for electronics and i have quite some knowledge on basic things and i know how to use soldering tools very well, as well as other mechanical tools and instruments.

So i thought its about time i finally started doing something i loved from the start 😀
And the fact that i need a new AT PSU 😁

Personally I do not recommend starting to build your own. There is a whole lot of stuff not known based on the schematic. For instance the transformers are unknown, so are component tolerances, capacitor voltage ratings and resistor power ratings and if there are any other special requirements for each part like safety. Sure you can guess what cap voltage rating or resistor power rating is enough, but I do recommend to start from a smaller projects instead of touching high power mains voltage projects.

As a hobby project, would it be OK to modify old or new ATX power supply connectors enough to provide AT power connectors? You can even provide -5V from -12V if ATX supply only has the -12V, or rig up the ATX supply wakeup pin to huge AT front panel switch. If you must, you could build the -5V regulator inside ATX PSU. While it's open, there is also chance to remove excess 3.3V orange wiring.

^ I agree with Jepael, for starters building a PSU from the ground up might be a bit hardcore. Better get some good ole cheap used PSUs and tinker with them.

I made before power transformers and electronic circuits that increase and decrease voltage. I also have books on power supplies, power amplifiers and schematics on many other things that fit in the area of increasing and decreasing voltage/current and stabilization.
I do not find it to be complex at all, i find it to be time taking to analyze.

I understand the basic concepts behind a lot of things when it comes to PSU, i am still not much informed when it comes to chopper PSUs, but i understand the basic principle behind them, as well as normal analogue PSUs.

I also made my own vitroplast and pertinaks boards with a lot of precision with home made tools.
Plus there is the battery charger project i made, but never fully completed due to transformer that i chose being very costly.

All in all, i dont care how complex it is, i know i can finish it.
What i am interested into are some common known problems when it comes to building an PSU, common failures and why they occur, and what would be the best way to get the most stable voltage.

Links of interest:

A Detailed Look Into PSUs from TechPowerUp.

Anatomy of Switching Power Supplies from Gabriel Torres' Hardware Secrets.

How a Switchmode Power Supply Works from C_Hegge's Hardware Insights.

Capacitor Safety In Power Supplies by Phaedrus.

BadCaps.net forum - Power Supply Design and Troubleshooting section

Awesome, will check them out 😀
Thanks!

Also, the AT PSU i mentioned in the first post is 4$. There are 10 of them. Should i buy more than 1? They are unused.

Got a couple bad pics of the Seventeam ST-230WHF AT:

Input filtering is non-existent 😵 (just a couple Y-caps at top right corner). But there are empty parking slots in the silkscreen to add commón mode chokes and X-caps which you could scrounge from dead PSUs. As far as the bad pic and wires allow to see, the output filtering doesn't look bad, with several PI coils and apparently decently sized caps. With some work on the input side that could be made into a decent AT PSU for retrocomps.

If you get one post here pics of the guts to scrutinize it better.

Aye aye !
I will buy one for further info.

Regarding old AT PSU's - what are the components that are likely to fail and cause damage? Is it just the caps? If yes then any in particular?

I ask because surely a refurb is preferable to building one from scratch. Can an old PSU be made 'good as new' without too much effort?

More or less the same than an ATX PSU, they're basically the same minus the +3.3V rail. Also there is no +5VSB, so this can't fail in AT PSUs 😀 . It depends strongly of the particular brand and model, a cheap chinese piece of junk will have much more weak spots than a Seasonic, but typically with decent PSUs it's the caps and the fan/s that start giving problems.

badmojo wrote:

Can an old PSU be made 'good as new' without too much effort?

On old PSUs, much better than new 😏 . As for the effort, well you need to open the PSU and start adding/swapping components. This could lead to tired wrists and sore backs occasionally 😀 .

StarTech still makes an AT PSU:

http://www.startech.com/Computer-Parts/PSUs/A … ply~PS2POWER230

I keep referring to this PSU, but nobody ever comments on it.

I switched out my Pentium 200MMX system with this PSU over a year ago and have had no problems.

Does anybody have any comments/suggestions regarding this unit?

^ Can't find any pics of its guts. From the little that can be deducted from the exterior it doesn't look bad. Fan grill is more or less as good as a stamped grill can be, and the label says there exists fan control.

No PSU estimation without vivisection!

I 2nd that KT7AGuy. The Startech 230Watt AT PSU is great. Bought one for my 486 DX4-100 rig. Works great and has -5v so there's no issues using for example your good old Sound Blaster CT1350B (Sound Blaster 2.0) which requires -5v on the rail. Startech are a decent brand and I've never had any issues using their hardware. Bought mine from eBay for US $32.85 from a seller named "buy".

Could you please take pics of its internals Borgie?

Hi TELVM, I'll see what I can do in 2 weeks as that rig is at my workplace (where I do all my builds due to not enough space at home) and we're closed due to the Christmas period. Sorry.

Hi, a little delayed but if you're still interested then here are the photos for the Startech 230Watt AT PSU.

That is actually a very nice PSU. Good input protection and filtering, plus good output filtering and decent quality capacitors (Looks like Teapo SC series). The two big primary caps are nothing to write home about, but they should do their job quite well considering input caps are not stressed that much. Pretty good PSU for an AT build. How much did you pay?

I paid $32 US from ebay. I actually just ordered another one from Amazon for around the same price. Not many companies out there still manufacture brand new AT power supplies. At first I was going to use an ATX PSU with an AT adapter as ATX PSU's are much better but then decided against it. Mainly due to 2 reasons, the 1st being the lack of -5V Rail and the 2nd being that ATX PSU's lack the connection to connect up your good old CRT monitor directly to the PSU. Oh and you're correct on the Teapo capacitors 😀 Not sure what brand the 2 primary caps are sorry.