Nooo, strong electronic burning smell...

[mechy]

To all operators of an A4000 Desktop configuration.
The original Commodore integrated 150W PSU is built using late '80s/early '90s PSU knowledge and has also been procured with latter-day Commodore frugality.

You might think that the A4000 engineers took this into account when constructing the motherboard/daughterboard/expansions and made them that little-bit more resilient. That might be the case. But none of them envisioned that the A4000D with the original PSU would be running anything in 2015.

I can't emphasise the importance of a good power supply enough. To quote that guy from Apollo 13 "Power is everything".
I recommend you replace the old inefficient (by design and by age) PSU with a more modern SFX of TFX form factor PSU. Both use modern PSU designs that operated at higher levels of current supply efficiency and run much cooler and quieter. Both can be integrated into an A4000D case and connect to the the motherboard with the low cost Amiga 4000 ATX PSU adapter + switch.

Especially if you are running high end CPU cards and a Mediator with PCI cards, but also if you are just running a pure vanilla, unadulterated, classic Amiga A4000/0x0 with only classic Zorro expansion boards. Protect your investment in nostalgic computing glory.

Nonsense, there is nothing wrong with the design or function of the original 4000 psu's.they are standard switching supply design used in most pc psu's. Only improvement in atx and such is if you go 80+ certified for a better powerfactor.-and those are counterfeited also in many cheaper ones..Although i prefer the skynet (easier to recap)design,the liteon ones are also ok,as a matter of fact there is quite a bit of filtering on the high voltage side of the liteon as well as mov's for surge protection.  Most of these psu's will run many more years if you recap them.

I have seen way more junk atx,miniatx,with horrid designs and missing any input protections.

In almost all cases the 150w a4000 psu will run decked out mediator setups with no problem if recapped. Its a true 150watts,notice the 5v rail which is what the amiga really loads down is weak on many atx,as a matter of fact most modern psu's concentrate on 12v and 3.3v now. i cant count the atx psu's i've seen with 5v poorly regulated and showing as low as 4.85v.

[mechy]

Interesting, I have been running these modules for a long time, several years in fact.  

http://www.amazon.com/gp/product/B009OP8G7Q?psc=1&redirect=true&ref_=oh_aui_search_detailpage

I ordered these on Oct 10th 2013, and they do state that they are 5v.

Thomas has good input on the module failure, but i suspect this is simply a case of a shorted dram chip. I run much dram through my simcheckII tester and have found some cases it reports chips on simms over the years as shorted. I discard them immediately.
The power draw/short that the simm pulled through the traces may of burnt one on the accelerator.

[mechy]

I don't disagree with you. When the A4000 was designed it was a standard, if low cost PSU for the time. It's not like Commodore were breaking new ground with amazing PSU tech.

And I agree with the recapping of the original PSU and while you're at it, putting in a quieter fan.
I just found it a lot easier to put in a modern, manufactured in this century, high quality PSU. Only a few OEMs make a SFX and/or TFX PSU and they are reputable brands and the PSUs are generally of the 80+ certified variety, and run extremely quiet.

Whilst it is true that ATX PSUs do place more focus on 12V, the 80+ have solid 5V performance.

You clearly agree that good clean power is important. You can get it by improving the original A4000 PSU or by getting a brand spanking new SFF PSU.


I wasn't implying that your PSU was dead. What on first glance is a regular running PSU can still be a culprit for many things that go wrong with one's rig.

I'm not saying you must buy a new PSU. But I would at the very least recap it as per mechy's inclination.

Don't want to hijack the thread,but i dont think you realize that skynet and liteon were 2 of the major psu makers since the early pc days. Commodore had nothing to do with the psu design other than passing them specs for size, cooling,  and power required. These are off the shelf standard pc psu's just like any pc used. The same basic power supply scheme is still the same today, the only difference is switching parts with less gate resistance and such and some run higher switching frequencies which is debateably better. sff,matx,tfx, it doesnt matter all the same designs and i can give you half a dozen examples of junk brands. Even some of the OEM brands fail and have substandard caps,poor filtering,horrible ripple,and shared rails. You are kidding yourself and others if you think new psu's are superior(well very few are).
Many a4000's simply fail because of overheating caused by fans being dirty,neglected or bad. When changing to a quiet fan the CFM needs to be adhered to since it also cools the entire case. Never speed reduce a 4000 psu fan.

[mechy]

Err I like to point out that some user(s) here do have 3.3v simm(s), but probably don't realize they are 3.3v simm(s).

It's the Micron MT4LC16M4H9 chips, you will find this on 64 & 128MB simms. see PDF docs.

Test here has shown their can fail in a very short time if voltage exceeds 5.5v, but at 5v no problems has been detected. A good sign there is a problem, the chip will get very hot to a point where you can't hold your finger on the chip.

ALL MODIFCATION AT YOUR OWN RISK.

Many simms are 5v tolerant even thought the datasheets dont list them as so, I have run a 128Mb 3.3v simm in a csa derringer for almost 6 years now. The simm doesnt show any heating and has always worked flawless, but as you say,buyer beware. I still think he had a chip short and draw excess current since only one of them fried and it took so long.