Don't leave your retrocomputer working unattended

[Xanxi]

Hi.

The title is something i have learnt from the Apple II folks i have been following and i am generally applying this good advice to every computer except the Amiga which i usually trust as if it was the first day.

Now i have here my main rig, the king of retrocomputers of my collection, the A4000D which is built of new mobo, and a bunch of cards and devices in excellent shape, either modern parts or serviced - recapped - repaired ones, powered by a Liteon A4000 PSU sold to me as recapped and cleaned. I use it a lot, usually stays on hours almost daily, except in the heart of the summer when it gets too hot too fast.
Yesterday, the PSU is dead of all a sudden. The computer has rebooted several times with blinking LEDs until they faded away like a dying Terminator eye and it was apparently dead.

Fortunately, i have been able to try it immediatly with another recapped PSU at hand, this one of the Skynet type.

The whole computer seems to be working again with apparently no damage, except for my Prelude Z2 half zorro edition and particulary the MPEGit module which sometimes works fine, and sometimes just gives a lot of statics.
And also my XBox 360 wireless controller + Mouster combo isn't working anymore with the DB9 extension cables i use to protect the ports themselves. +5V is no more than 4,3V now out of the DB9 port + cable. Without cable, around 4,5 to 4,6V it works again.
The Skynet PSU is according to my memories a but less powerful than the Liteon one and it seems that i am losing more than before on the +5V line.
The A4000 is notoriously weak on +5V with attenuation throughout the computer and too power hungry mice are know to cause issues, that's why i have gone wireless both for joypad and mouse.

I hope i will be able to have my Liteon one repaired or upgraded. The Skynet is also more noisy despite equiped with a so called silent Noctua fan.

Wondering why it failed, i think my A4000 is too stacked for my PSU and i have asked chatGPT to estimate the total power requirements.
The hardware list is:
- Amiga 4000 ACILL mobo
- CyberStorm MK2 68060@50 MHz +128 MB RAM
- ZZ9000
- Deneb USB
- Prelude Z2 half zorro + Mpegit
- A2386 with Cyrix 486 SLC 50 Mhz + 8 MB RAM + STB Nitro VGA ISA + soundcard MK8330 ISA
- soundcard USB SB Creative Play 3 internally on the Deneb
- USB NIC
- SIDBLaster USB with ARMSID
- 4 3,5' floppy drives including 1 internal Amiga, 1 internal for bridgeboard and 2 external Amiga ones
- internal USB hub to the Deneb powered from the PSU
- USB 8GB small stick for backups
- card readers (combo with the bridgeboard floppy drive powered from the PSU with SD and CF for emulator drives
- serial MIDI adapter
- parallel AEGIS SoudMagic digitizer
- Amiga 4000 keybaord
- Microsoft USB mouse with HID2Ami v2
- gamepad Microsoft XBox 360 usb wireless with Mouster
- SATA to IDE SSD
- IDE laptop CR-ROM

It says it should need between 120W while idle to 180W in full charge, with most of the load on the +5V. ChatGPT recommends 20A minimum and 22 to 25 to be fine and only 1A for the +12V.

Whereas the Liteon PSU is according to Liteon sticker 151,8W with +5V 20A +12V 4A -12V 0,3A, and the Skynet one is +5V 18A, +12V 4A and -12V 0,4A.
I think the 2A less on the Skynet are showing on my setup.

I hope my malfunctionning MPEGit is related to the lack of 5V and nothing more serious (technical advice welcome here).

Now maybe i should remove stuff from that computer but i can't live with empty slots and ports (only the DB23 port remains unused here).



Meanwhile, i have spent the last weeks to care for my nice Apple IIGS setup, a computer i like, but i don't trust its old PSU, even with RIFA removed. It is making strange buzzing and noises and i am about to replace it with a picoPSU. I never let this one unattened as the Apple II guys said to me.

Opinions welcome about how to repair the Liteon and what to do in general.
Only ATX PSU is not an option for that computer. I have a SF450 for another secondary A4000 still in WIP for a long time, but this one never activates its fan because of lack of +12V load and more importantly the A2386 doesn't work with it.

For your information, i have been in touch in 2022 with Jens @ Icomp who said IComp might be doing a big box version of the CA-PSU, with no precise schedule, as he doesn't like ATX + Amiga either.
No more information so far though, three years later.

For further reference, pics from the two types of A4000 PSU.

 

[amigean]

That was a close one!

Why are you against ATX PSUs? Surely they are safer, assuming technology and safety progressed over the past 30 years? I have adapted Corsair psus in my heavily expanded A3000 and A4000 (currently being rebuilt as it got transplanted to a Hese Alice A4000+ mb) and very happy with them.

 

[Xanxi]

Because ATX /SFX are unregulated on the +5V unless sufficient load is applyed on the +12V and the Amiga won't do it by itself.
It is said to put a resistor on the +12V but i don't want to release more heat in an overcrowded computer and even risk to start a fire.
Besides some of them won't make their fan spin under low load, just like the Corsair SF450.
Also the SF450 and other further models by Corsair are all 20A on +5V which is not much better than the original PSU, even if they would probably be more efficient to really reach 20A.
And for an unclear reason, the A2386 bridgeboard won't start with the SF450, or some other ATX PSU such a someone also reported on EAB.
I think there is a market for a strong and reliable big box Amiga specific PSU and hope that IComp will finally do something.

 

[Xanxi]

Good news, Jens confirms that IComp still has big boxes PSU "in the pipe", but he doesn't say how long is the pipe.

 

[miggymad]

Good news, Jens confirms that IComp still has big boxes PSU "in the pipe", but he doesn't say how long is the pipe.

That magicial Amiga quote of "two more weeks" springs to mind ...

 

[Xanxi]

Now looking for a device to test my PSUs.

I have a multimeter but it seems one old 3,5' harddrive connected is not enough a load to test the PSU.

So i am looking at this thingie

ATX Binghe 20/24 Pin LCD Digital Sound Alarm Power Tester Support ATX/ITX/IDE/HDD/SATA/BYI : Amazon.fr: Computers

ATX Binghe 20/24 Pin LCD Digital Sound Alarm Power Tester Support ATX/ITX/IDE/HDD/SATA/BYI : Amazon.fr: Computers

www.amazon.fr

I can't find any information about resistors inside to apply a load but i guess there should be something.
And the short manual says to plug the ATX connector, turn on the device, then try Molex, Sata and whatever.
The A4000 PSUs are AT so i wonder if i could just plug a molex alone and test the PSU from it.

 

[amigean]

Thanks for the response, I wasn't aware of these issues!

I wonder now, if the real reason my original A4000 motherboard died was the Corsair VS 450 psu I had powering it. In fact, it had been flakey for a long time before it kicked the bucket but I never suspected the PSU as my confidence on Corsair was high. ChatGPT tells me that the VS450 being designed primarily for 12v used in modern PCs, it would struggle or provide unstable 5v loads for my heavily expanded A4000.

My dead A4000 had its chips transplanted by Hese to one of his A4000 'Alice' remake motherboards but I haven't gotten round to rebuilding it.

I am now on the lookout for a new PSU. My A3000 has an Corsair SF 450 which is great and rock solid. Do you think this one will work?

https://www.amazon.es/gp/aw/d/B07MT3VFMB/ref=ox_sc_act_title_2?smid=A12LJDCIB792OX&psc=1

 

[Xanxi]

The Corsair PSU is certainly worthy of confidence, when using a PC.
As for the Amiga, a lot of people are using it or similar one, but there is no data on how they adress the +12V load issue. Hence this is a risk i don't want to take for my rare and expensive hardware. Besides, its fan won't turn on, so there is no more airflow in the A4000D, where is it not easy to install other fans (unless using one of the newer cases by Ordyne or the black heavy duty case by Arymanx).
About that beQuiet PSU, you should search how it is regulated from confirmed sources and not only Amazon description.

 

[amigean]

thank for the advice - indeed I need to do more research, and measure with a multi-meter how well my current Corsair VS450 handles +5v.

I have transplanted its guts to the original PSU housing and replaced the built-in fan with a permanently connected one. I run a real 3.5 HDD which draws 12v but the load is probably too small. The VS450 is probably ok for an unexpanded A4000 but given all my expansions (Warp4040, Picasso IV, Rapidroad USb+lan, Tocatta, plus fans) it may not be enough: its specs say it can do 16A on 5v, which is not a lot, but if stable, could be fine. Sadly, I don't have enough knowledge to test it (though I'd love to learn how).

 

[Xanxi]

This one has a detailed review here https://www.tomshardware.com/reviews/corsair-vs450-power-supply,6076-2.html

ChatGPT has checked it for me in the perspective of the Amiga and says :

"
What the measurements show (cross-load behaviour)

Tom’s Hardware performed two dedicated cross-load tests, and the results are quite revealing:

CL1: Heavy load on the 3.3 V and 5 V rails, almost no load on 12 V.
→ The 5 V rail drops to 4.46 V, which is below ATX spec.
→ The 12 V rail rises to 12.64 V.

CL2: Heavy load on the 12 V rail, very light load on 3.3 V and 5 V.
→ The 5 V rail jumps to 5.30 V, above ATX spec.

The reviewer clearly states that because the VS450 uses a group-regulated secondary, the PSU cannot maintain proper voltage regulation when the loads are unbalanced. In other words, when one rail is heavily loaded and the others are lightly loaded, the voltages drift out of specification."

Forgive me to use ChatGPT, that's an habit that i have taken from @darefail about retrocomputing, but i usually don't trust it for my work.

Anyway, that PSU seems probably dangerous as is, and i read that one harddrive is not a sufficient load for the +12V. They say to put resistors or car 12V lightbulbs to draw on it. May be the A4000 need a Christmas tree as an accessory in this season.

 

[amigean]

Point taken! I'm on the lookout for a replacement...

 

[Xanxi]

Meanwhile, i have investigated my MPEGit problem as it has repeatedly shown the same problem of starting to work then making only noise when playing mp3. After checking it visually it seems fine. But now the whole Prelude is not recognized at all in the computer and seems dead. An Amiblaster Deluxe has taken its place and works fine in the same slot.
That seems to be the only part which has suffered from this incident.
I need to try it on another computer and i hope it can be repaired.

 

[amigean]

Good luck! You can ask Hese here, he does amazing repairs, recaped some Zorro boards for in the past too.

Speaking about Zorro cards, my RapidRoad (bought here ages ago) never really worked properly and i'm suspecting the PSU may have had something to do with it. I need to try it on my A3000 while I sort out a PSU for my A4000

 

[sbrentson]

Regardless of overall distribution, it sounds like you’re going to struggle to find a PSU that can provide over 100W from the 5v rail.

I personally run a 4000D with a TF4060@50mhz, Prometheus Firebird, PrPMC800(?) PPC @800mhz “Ragnarok”, Voodoo3 3000 and a PCI USB adapter with a Corsair SF750 without issue.

Contrast that to my “bench” cheap Chinese 500W POS that can barely hold 4.6 volts with a MB + 3640. The SF750 is rock solid at just under 5v with the full PCI stack drawing power. I only discovered this difference when I was trying to troubleshoot drops to 2.5v on my 3.3v rail for a z3660 build. Spoiler alert - Amigas crashes shortly after boot.

The point is that Corsair does a much better job of regulating 5v for an imbalanced load. By the way, Corsairs latest SF spec has dropped -12v entirely. Amiga still needs that.

 

[Xanxi]

That's interesting to compare. I have asked ChatGPT again and it seems your A4000D, despite being apparently more powerful than my more classical setup, needs much less power. It estimates you need 15A (better 18-20) on +5V and 2-3 on +12V.

Why mine does need more?
- stuff with FPGA like ZZ9000 and Deneb needs more than the PPC itself
- my internal USB Hub eats a lot of power with a lot of USB stuff
- i have a lot of mechanical drives which can cause peaks
- Voodoo 3 takes 2,2 A on +5V versus 3 to 4A for the ZZ9000 (even though i remember the Voodoo 3 as a hot and power hungry beast in my SuperSocket 7 computer of the old time)

About that SF750, it seems to cover your needs, but what measures did you take to load the +12V enough? Is your +5V stable without any supplementary trick? And does its fan spin?

Not that if i returned to my older C64/3D with scandoubler that i was using before the ZZ9000, i could use only 1,3 to 1,8A on +5V versus 3 to 4A on the ZZ9000 according to the AI estimates. Amazing!

You are right that there is apparently no PSU currently available on the market as new with more than 100W on +5V. That's why i hope iComp will make something tailored for the Amiga and i will be willing to pay good money for it.

 

[sbrentson]

SF series is DC-DC regulated, so it doesn’t need 12 V load for 5 V stability — rock solid rails, fan stays mostly off. This is in contrast to a more budget unit such as the Corsair VS line mentioned earlier in this thread. That line of PSUs uses group-regulated rails, which rely on a certain balance between 12 V and 5 V loading.

To be honest, I never questioned, nor was even aware, that I needed to worry about the voltage balance across the rails when substituting a modern PSU in an Amiga. The SF450 was suggested when I purchased the aftermarket case here. Only SF750 was in stock at the time. For our purposes they should be identical as you don’t get any additional overhead from the 5v rail, regardless.

My 12v load consists of a 5.25 “ optical drive, 3.5 “ floppy and 3 Noctua case fans. Fraction of an amp?

 

[Xanxi]

Main problem of the Corsair SF450 seems to be the no fan operation.
Many people have been talking about it on the internet and there is someone on the link below complaining that his PC is hotter than his toaster. The fans seems to activate on 50% load (215 W) and not temperature. The newly made A4000 cases allow for some more fans but not the original A4000 so that's no good, it would melt.
And there is still the mysterious problem which makes the A2386 not booting with it.

 

[sbrentson]

That Reddit post makes zero sense. The author is remarking that CPU temps idle at 70c and throttle at 95c under load. What in the heck does that have to do with the PSU fan? It’s sounds like the author has the impression the PSU fan is a case fan. It’s likely the author had no case fans and since the SF450 didn’t need to run its fan, he was cooking his CPU. If the PSU was getting critically hot, OTP would shut it off.

Today I decided to move several GB of WHDLoad content from my internal IDE CF to the z3660 SCSI Sd card which took literally all day on my 4000D. I left for 3 hours came back home and copied several more hours. It never finished because shortly before bed time my smoke detectors went off and there was a small fire where my Amiga once sat.

No. That’s not what happened.

The hottest thing in the system was the z-turn FPGA at around 56c. The systems fine.

Don’t believe everything you read.

 

[Xanxi]

Yes, it is strange that a PC case would have no other fan, but for the A4000D it is the usual.
I used too to leave an Amiga copying files all night but i would hesitate to do so for my big box computers now.
These days it is cold in Paris, my A4000D is fresh. The ZZ9000 is at no more than 58-60°C whereas it reaches 75°C in one hour in summer, and another sensor inside the case is around 42°C when it shows 55°C in summer. That's why i always call it the winter computer.

 

[Xanxi]

More PSU explosions at home today.

As i got a nice free afternoon for once, i intended to do something from my very long to do retro list.
The simplier was to work on an old spare Dreamcast which has been waiting for long to get a new case, new Dreampsu and new GD-EMU.
As i forgot what was working or not on this one, i plugged it. It started to the menu screen just fine and a few minutes later while i was making some cofee, again an explosion with a lot of white smoke throug the fan vent.

It appears a buldging cap from the PSU did blow away releasing some nasty liquid into the case.
The Dreamcast still appears to work with a replacement PSU, even though the GDROM drive seems dead. Unfortunately i am stuck again because the GDEMU i have in stock seems faulty and i now i recall it was probably already a couple of years ago. Need to have another one, and appart from replacing the coin cell and the fuse from the gamepad board, i have done nothing, even my replacement case happens to be broken with no way to screw the switch. Until probably several months for my next attempt.