386SX wrote on 2024-03-15, 16:43:

Which is the status of modern "new" retro oriented -5V compatible PSUs for AT mainboards? Are there any new ones I'd use on a AT or ATX late 90 system on the market built in modern times specifically for them?

Just get yourself
1 of these: https://uk.farnell.com/stmicroelectronics/l79 … 141?ost=1087141
and
2 of these: https://uk.farnell.com/panasonic/eeufc1v330b/ … dial/dp/3253996
and you can make and add a -5V pin (white) [pin+wire from a dead PSU], directly to any PSU's ATX connector that is missing it.
The converter is outputing -5V (white) from -12V (blue) and ground (black). So it would be preferable to use it with a PSU that outputs 0.5A (not 0.3A), on the -12V.

I made mine on a little PCB, and a bit more complicated.. but you don't have to.. and you don't need a PCB.
I later isolated mine by putting it in a little plastic case from inside a Kinder chocolate egg.

Alternatively, you can incorporate the convertor into one of these ATX extensions, or ATX-to-AT adapters, that (both) already have the white wire... Which would make things much easier to build, AND detachable! 😀 (just DON'T ever connect them to a PSU that already has the -5V white wire)

(EDITED) TL;DR : This project's electronics are based on the Voltage Blaster project, but DOES NOT connect to an ISA slot, but to the ATX connector.
You can also use these Voltage Blaster pictures to understand how to connect everything:

I hope it's clear

I use the voltage blaster mini https://www.youtube.com/watch?v=b2XOo_8uzvw

But this is the best solution I’ve seen so far. See at 5:30. -5 is injected in at the ATX adapter.

https://youtu.be/iGlIgqNpK50?si=asg80lmBwxI7Dh4b

Thanks both. I think the solution before the AT connector seems the better one and look better to insert the voltage at the PSU level instead of the bus rail.
As modern PSU voltages/balances to use, any problem using them for such different usage? Is it safe in the long run if eventually the converter would fail?

zuldan wrote on 2024-03-15, 21:34:

But this is the best solution I’ve seen so far. See at 5:30. -5 is injected in at the ATX adapter.

https://youtu.be/iGlIgqNpK50?si=asg80lmBwxI7Dh4b

81D4629F-06AC-46EB-886F-635D637D3382.jpeg

386SX wrote on 2024-03-16, 07:21:

Thanks both. I think the solution before the AT connector seems the better one and look better to insert the voltage at the PSU level instead of the bus rail.
As modern PSU voltages/balances to use, any problem using them for such different usage? Is it safe in the long run if eventually the converter would fail?

The solution I posted IS before the AT connector of the motherboard... 🙄
Also requiring the minimal amount of components to create, while maintaining compatibility with any case and motherboard
(a 90 degree ATX connector may present problems with many motherboards. That's why I recommended an ATX extension, or ATX-to-AT adapter, for anyone who wants to make it detachable from the PSU.).

The components I linked to, are of really good quality... (most likely far better than in the average PSU )
But if the converter IC should fail, it should remain open, and basically just not output -5V anymore, while not consuming anything.
If by some mishap, it fails and shorts the -12V rail to Ground; than that's up to the PSU to handle. A PSU with good short-circuit protection, would simply not turn on anymore until the short is removed. Except for in the case of the absolute most shittiest PSU, the PC components should very VERY most likely remain unharmed even if the convertor fails.

B24Fox wrote on 2024-03-16, 19:42:

The solution I posted IS before the AT connector of the motherboard... :rolling_eyes: Also requiring the minimal amount of comp […]
Show full quote

zuldan wrote on 2024-03-15, 21:34:

But this is the best solution I’ve seen so far. See at 5:30. -5 is injected in at the ATX adapter.

https://youtu.be/iGlIgqNpK50?si=asg80lmBwxI7Dh4b

81D4629F-06AC-46EB-886F-635D637D3382.jpeg

386SX wrote on 2024-03-16, 07:21:

Thanks both. I think the solution before the AT connector seems the better one and look better to insert the voltage at the PSU level instead of the bus rail.
As modern PSU voltages/balances to use, any problem using them for such different usage? Is it safe in the long run if eventually the converter would fail?

The solution I posted IS before the AT connector of the motherboard... 🙄
Also requiring the minimal amount of components to create, while maintaining compatibility with any case and motherboard
(a 90 degree ATX connector may present problems with many motherboards. That's why I recommended an ATX extension, or ATX-to-AT adapter, for anyone who wants to make it detachable from the PSU.).

The components I linked to, are of really good quality... (most likely far better than in the average PSU )
But if the converter IC should fail, it should remain open, and basically just not output -5V anymore, while not consuming anything.
If by some mishap, it fails and shorts the -12V rail to Ground; than that's up to the PSU to handle. A PSU with good short-circuit protection, would simply not turn on anymore until the short is removed. Except for in the case of the absolute most shittiest PSU, the PC components should very VERY most likely remain unharmed even if the convertor fails.

Yes I meant that the solution in the ATX adapter seems the best compared to the ISA PCB solution. I am sure my 386 board is unstable without the -5v so having it at the AT connector is indeed what I wish. I will go for it, any modern low watts PSU I can use along with this that has been tested having also a stable +5v too?

Honestly, for the kind of current a 386 system will draw, any brand-name PSU will do.

Minutemanqvs wrote on 2024-03-17, 09:42:

Honestly, for the kind of current a 386 system will draw, any brand-name PSU will do.

Thanks, of course the current will be low but I wonder how much stable the 5V rail would be and filtered from peaks even higher than the expected.

386SX wrote on 2024-03-17, 07:00:

any modern low watts PSU I can use along with this that has been tested having also a stable +5v too?

The cheapest decent PSUs, seem to be the Segotep ATX-500WH that I reviewed here, and the LC Power LC6560GP3 v2.3 80+ Silver.
Though nobody actually measured their output stability with an Oscilloscope; they DID seem to pass the test of time, with some users here.

But I really recommend giving this entire thread a quick read.

sorry for the huge bump.
I stumbled upon an old Tagan 580w I have, with still original box:
It's modular very nice blabla and it also has a nice switch which allows to change the settings from split to combine (for 12v rail) and it's rated for 180w combined (3.3v: 26A 5v: 30A), would it be ok? I still need to check if it works properly.
Otherwise a romanian user would be available to order a couple of Segotep from the website, please?

Nemo1985 wrote on 2025-02-01, 20:13:

it's rated for 180w combined (3.3v: 26A 5v: 30A), would it be ok? I still need to check if it works properly.
Otherwise a romanian user would be available to order a couple of Segotep from the website, please?

Ok for what? You haven't mentioned any PC or specs.

Unfortunately, the Segotep ATX-500WH hasn't been in stock pretty much anywhere for quite some time now.
Bright side is: the specs you mentioned on that Tagan, are at least as good as on the Segotep ATX-500WH.

B24Fox wrote on 2025-02-01, 22:56:

Ok for what? You haven't mentioned any PC or specs. […]
Show full quote

Nemo1985 wrote on 2025-02-01, 20:13:

it's rated for 180w combined (3.3v: 26A 5v: 30A), would it be ok? I still need to check if it works properly.
Otherwise a romanian user would be available to order a couple of Segotep from the website, please?

Ok for what? You haven't mentioned any PC or specs.

Unfortunately, the Segotep ATX-500WH hasn't been in stock pretty much anywhere for quite some time now.
Bright side is: the specs you mentioned on that Tagan, are at least as good as on the Segotep ATX-500WH.

Unlucky I tried the tagan and it did a bang probably it didn't like being in a basement for 10 years...
I'd need a couple of those psu because I have 2 socket a builds.
From what I understand of romanian (I'm italian), this should be in stock: https://www.pcgarage.ro/surse/segotep/atx-500w-1/

Can you tell me if the shop ships abroad?
Many thanks.

Nemo1985 wrote on 2025-02-01, 23:01:

Unlucky I tried the tagan and it did a bang probably it didn't like being in a basement for 10 years... I'd need a couple of tho […]
Show full quote

B24Fox wrote on 2025-02-01, 22:56:

Ok for what? You haven't mentioned any PC or specs. […]
Show full quote

Nemo1985 wrote on 2025-02-01, 20:13:

it's rated for 180w combined (3.3v: 26A 5v: 30A), would it be ok? I still need to check if it works properly.
Otherwise a romanian user would be available to order a couple of Segotep from the website, please?

Ok for what? You haven't mentioned any PC or specs.

Unfortunately, the Segotep ATX-500WH hasn't been in stock pretty much anywhere for quite some time now.
Bright side is: the specs you mentioned on that Tagan, are at least as good as on the Segotep ATX-500WH.

Unlucky I tried the tagan and it did a bang probably it didn't like being in a basement for 10 years...
I'd need a couple of those psu because I have 2 socket a builds.
From what I understand of romanian (I'm italian), this should be in stock: https://www.pcgarage.ro/surse/segotep/atx-500w-1/

Can you tell me if the shop ships abroad?
Many thanks.

Unfortunately, that is not the "Segotep ATX-500WH" (https://www.pcgarage.ro/surse/segotep/atx-500wh/ )
It's the "Segotep ATX-500W".
The "Segotep ATX-500W" & the"Segotep ATX-500W12" are pieces of crap that will literally burn your house down. Believe me, I tried 'em.
(Also, the store does not ship abroad)

Also, Socket A can range from a 30W CPU, to an 80W CPU... So be mindful of everything else you add that might pull on the 5V rail.

B24Fox wrote on 2025-02-01, 23:21:

Unfortunately, that is not the "Segotep ATX-500WH" (https://www.pcgarage.ro/surse/segotep/atx-500wh/ ) It's the "Segotep ATX-5 […]
Show full quote

Nemo1985 wrote on 2025-02-01, 23:01:

Unlucky I tried the tagan and it did a bang probably it didn't like being in a basement for 10 years... I'd need a couple of tho […]
Show full quote

B24Fox wrote on 2025-02-01, 22:56:

Ok for what? You haven't mentioned any PC or specs.

Unfortunately, the Segotep ATX-500WH hasn't been in stock pretty much anywhere for quite some time now.
Bright side is: the specs you mentioned on that Tagan, are at least as good as on the Segotep ATX-500WH.

Unlucky I tried the tagan and it did a bang probably it didn't like being in a basement for 10 years...
I'd need a couple of those psu because I have 2 socket a builds.
From what I understand of romanian (I'm italian), this should be in stock: https://www.pcgarage.ro/surse/segotep/atx-500w-1/

Can you tell me if the shop ships abroad?
Many thanks.

Unfortunately, that is not the "Segotep ATX-500WH" (https://www.pcgarage.ro/surse/segotep/atx-500wh/ )
It's the "Segotep ATX-500W".
The "Segotep ATX-500W" & the"Segotep ATX-500W12" are pieces of crap that will literally burn your house down. Believe me, I tried 'em.
(Also, the store does not ship abroad)

Also, Socket A can range from a 30W CPU, to an 80W CPU... So be mindful of everything else you add that might pull on the 5V rail.

Oh damn... ok I will need to find something else, then, thank you for the help, I was looking for something beefy, stronger as psu is never a bad decision 😁

Both Segotep and Tagan are some of the worst brand you can buy for a PSU. I think Tagan was caught at some point putting concrete or iron in their PSU to make them heavier ! I would not use Segotep even if i would got one for free!
For 5V heavy systems such as Socket 462 without the P4 connector I would choose either a high end Corsair - example RM1000i has 25 A on the 5V rail with a 150w combined on the 3.3 and 5v rail - or a period correct Enermax such as this one:

nd22 wrote on 2025-02-06, 07:30:

Both Segotep and Tagan are some of the worst brand you can buy for a PSU.

I've been using these Segotep PSUs for almost 5 years (I have more than 10 at this point), none have died on me, and at least one of them has already exceeded 10 000 hours of usage by now.
If you are comparing them with top tier modern PSUs then, yeah, of course they are "pieces of crap". But if you instead compare them with the no-name PSUs that most of us used to have in our PCs 20 - 30 years ago, they are actually not that bad.

I do agree, though, that there are better options for higher-end Athlon/Athlon XP systems that draw a lot of current from the 5V rail.
I, for one, was lucky to find 6 x (cheap & NOS) Thermaltake TR2 470W PSUs (22A on 3.3V / 32A on 5V, combined 220W) from a seller in Bucharest, and these are wonderful for such a system. I also bought a bunch of Seasonic S12II-520 Bronze 520W (24A on 3.3V / 24A on 5V, combined 130W), back when they were still available at PCGarage, these are also a decent choice for most builds.

But my main workhorse, the one I use with my primary test bench, remains the Segotep 500W, and it hasn't give me any reason to doubt it after all of these years.

Seasonic is also a very good brand, up there with Corsair and Enermax, however I measured the voltages of an old Tagan PSU and they were all over the place! I never used Segotep but I would like to see the voltages after a few years of use.
I used the Corsair RM1000i with the 1400C CPU and geforce3 ti500 on an Abit KG7-raid board and it ran just fine with no voltages outside specs which is amazing considering how much 5V are needed for this system!
As a side note the best site for calculating the power and voltages required for your system will be shutdown at the end of this month 🙁 !!!
https://outervision.com/power-supply-calculator

nd22 wrote on 2025-02-06, 08:33:

I never used Segotep but I would like to see the voltages after a few years of use.

If you put a lot of load on the 5V rail with a more power hungry platform (higher frequency Thunderbird CPUs, Bartons, etc), the voltages can get as low as 4.7V. Not great, not terrible... still within the +/- 10% ATX spec, though.
With socket 7, socket 370 (or even slower socket A CPUs), voltages remain steady at ~ 4.9 - 5.0V.

bloodem wrote on 2025-02-06, 07:51:

But my main workhorse, the one I use with my primary test bench, remains the Segotep 500W, and it hasn't give me any reason to doubt it after all of these years.

Did you actually mean the Segotep ATX-500W ?? ...or is it the ATX-500WH?

B24Fox wrote on 2025-02-06, 09:10:

Did you actually mean the Segotep ATX-500W ?? ...or is it the ATX-500WH?

The ATX-500WH, this one: https://www.pcgarage.ro/surse/segotep/atx-500wh/

Athlon 1400C + 2*1gb DDR + gf3 ti 500 + Abit KG7-raid + HDD + DVD = 30A required on the 5V rail + 180W combined on the 3.3V+5V rail.
Corsair RM1000i : 4.95V measured on the 5V rail while running 3dmark 2001 in a loop!
Cons to this power supply: 200 euros new!!