Lots of questions about PSU's for both Amiga 4000 and PC's

limboy777

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Hello

Im wondering if my fellow Amibayers can help with some questions on PSU;s.


1. I have an Amiga 4000 and the PSU in it is the original one. I dont have much confidence that a PSU thats over 20 years old will last forever especially as I have invested some money on the A4000. Is the A4000 a standard AT or ATX PSU with amiga connectors?

2. Related to the above, I have seen a post somewhere on the internet where someone modified an A4000 PSU and stuck inside an ATX PSU with the front power button working with it. Does anyone sell these or provide this service?

I think a smaller PSU but with bigger power output would be ideal to take care of upgrades and also give better airflow.


3. I have some old 386 and 486 PC's. One of the PSU's has died in one of them, the PSU are very small and not common so I cant just buy a new one. Can this be repaired? (PSU is AT type).

4. The PSU that is dead is only 60watt. If I find a small enough one to fit, Im assuming it doesn't matter if the output is higher? (it doesnt have any additional power hungry upgrades).

5. I have seen ATX to AT adapters. Assuming these are safe to use? i.e could I find a small ATX PSU and use it with the adapter without doing anything else?
 

Jameson

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Hello

Im wondering if my fellow Amibayers can help with some questions on PSU;s.


1. I have an Amiga 4000 and the PSU in it is the original one. I dont have much confidence that a PSU thats over 20 years old will last forever especially as I have invested some money on the A4000. Is the A4000 a standard AT or ATX PSU with amiga connectors?

2. Related to the above, I have seen a post somewhere on the internet where someone modified an A4000 PSU and stuck inside an ATX PSU with the front power button working with it. Does anyone sell these or provide this service?

I think a smaller PSU but with bigger power output would be ideal to take care of upgrades and also give better airflow.


3. I have some old 386 and 486 PC's. One of the PSU's has died in one of them, the PSU are very small and not common so I cant just buy a new one. Can this be repaired? (PSU is AT type).

4. The PSU that is dead is only 60watt. If I find a small enough one to fit, Im assuming it doesn't matter if the output is higher? (it doesnt have any additional power hungry upgrades).

5. I have seen ATX to AT adapters. Assuming these are safe to use? i.e could I find a small ATX PSU and use it with the adapter without doing anything else?

Hi there,

Okiez. 1. - The A4000 does not use a standard ATX power connector. However, replacing the power supply is quite easy and painless. You have a couple of options.

[a] - if you are okay with a soldering iron then you simply need a new ATX PSU - unlike the A2000 and A3000, the A4000 does not require the -5v line which is good as most modern ATX (24 pin) PSUs no longer have this line. You just open the A4000 PSU, remove the inards. Desolder the wiring hardness. Take your ATX PSU, desolder its wiring harness. Solder the A4000 wiring harness to the ATX PSU PCB at the correct points (consult this VERY helpful webpage for wire colours - http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_Power_supplies/amiga_power_supplies.html ). Then install the ATX PSU PCB in the A4000 PSU casing and bingo! You have a nice new ATX PSU which still looks and fits like the original A4000 PSU. Oh, just remember to connect the PSU ON signal wire to ground (green ATX to any black wire). This way the psu will actually come on with the A4000 PSU switch. Or, you can wire the mains voltage coming in straight to the ATX PSU and then connect a ground wire to one side of the A4000 PSU switch and the green wire to the other. Either way works.

- buy an ATX PSU to A4000 harness adapter. These work and are quick and easy, but then you aer stuck trying to fit an ATX PSU casing into your A4000 and it does not look original.

2. - Yessum, refer to point "a" above. It looks neater, better airflow and is quite easy to do if you simply follow the wiring pinouts on the webpage I linked.

3. - Usually PSUs die from the caps going in them. The parts are cheap, but the labour less so. To answer your question it can definitely be repaired, but it is usually much cheaper and easier to simply replace the PSU, or if a non standard PSU casing then replace the innards, but remember, being an older AT motherboard it MAY require that -5v line - check. If so you need to look for an older type PSU. Some ATX 20 pin PSUs havethe -5v line, but not all.

4. - Higher is better. The voltage will be the same, only the amperage. Amperage works in such a way that the unit will only draw what it needs. For instance, if you have a 500watt PSU and your system only needs 10watts then it will work fine and the PSU will only be under slight load to deliver what is required.

5. - Yes, they are safe, however again, check the -5v requirements!

Hope this helps.
 

limboy777

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Hi Jameson

Thanks for your quick replies.

Im not handy with a soldering iron. Is this something you have done previously and could do as a service for me?:p
 
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Jameson

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Hi there limboy,

not probs mate - happy to help. I have done all of my Amiga PSUs, which includes 5 x A4000Ds (never owned a 4000T :( ). Well, I would be happy to do it for you (free of course), however the postage both ways might make it uneconomical - remember, I am in Australia. :) There is probably a helpful fellow Amigan in ole' blighty who would be happy to help. But, if you don't do any good then I would be happy to help you out.

Alternatively, it is quite easy. If you wanted to attempt it yourself I would be happy to converse with you and talk you through it.

Let me know how you go.
 

limboy777

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Jameson,

I had lots of the same questions quite a while back. You can look at the questions I asked along with answers and my A4000D ATX mod using the links below.

https://www.amibay.com/showthread.php?2616-What-s-a-good-ATX-power-supply-for-an-A4000D

https://www.amibay.com/showthread.php?7593-My-A4000D-ATX-Mod

Good luck!

Heather

Thanks Heather for the links.

I think I will have to put a wanted ad for a modified PSU. I dont have the skills to do it myself!
 

limboy777

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Hi there limboy,

not probs mate - happy to help. I have done all of my Amiga PSUs, which includes 5 x A4000Ds (never owned a 4000T :( ). Well, I would be happy to do it for you (free of course), however the postage both ways might make it uneconomical - remember, I am in Australia. :) There is probably a helpful fellow Amigan in ole' blighty who would be happy to help. But, if you don't do any good then I would be happy to help you out.

Alternatively, it is quite easy. If you wanted to attempt it yourself I would be happy to converse with you and talk you through it.

Let me know how you go.

Thank you for your kind offer. I will see if I can find someone who can do it locally but if not I will take you up on your offer pending shipping costs (hopefully not too expensive!).
 
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