retardware wrote on 2021-09-06, 18:26:Now that is an interesting observation.
Personally, I was lucky, had no tantalum explosions, just one quietly shorted one that p […]
Show full quote
Now that is an interesting observation.
Personally, I was lucky, had no tantalum explosions, just one quietly shorted one that prevented the PSU from starting (Took some time to find out which one it was...).
Maybe it's a good idea to put the PSUs on the test bench before deciding whether to use or throw them away.
I threw away lots of PSUs after my big test session for my article on the German classic-computing.de forum.
The worst one ("working", but with leaky caps) had 14+V overlaid with 2V ripple... a true killer!
Sometimes there are well designed PSUs that are crippled by abysmal caps, Antec units from the early to mid '00s are the leading examples of that. Whenever I get a used power supply, I try to identify candidates worthy of being refurbished. In those cases a recap + a new fan is all it takes to have a solid power supply, but it is definitely a good practice to perform some reliability tests before using it on valuable hardware. Of course, any unit with burn marks or multiple component failures is a no go in my book, at some point the cost of replacing components is just not worth it, especially without knowing the previous history of the PSU and what kind of stress/heat it was subjected to.
retardware wrote on 2021-09-06, 18:26:In short, there are many (and quite a few ATX)AT PSus that have very bad crossloading behaviour.
The worst ones that I tested al […]
Show full quote
In short, there are many (and quite a few ATX)AT PSus that have very bad crossloading behaviour.
The worst ones that I tested almost reached 15V on the 12V lines when only (and heavily) loaded on +5V.
A 3.5" HDD typically draws less than 1A, which does not help much (the 5.25" drives sucked 2+A).
This is one of the reasons why I like Seasonic... they all stay inside the ATX voltage tolerances specs.
Yes, some AT units, especially earlier ones required a certain balance between the +5V and +12V loads... after all that's why IBM supplied a chunky 50W resistor on the 5170 to act as a dummy load on +12V when you didn't have an HDD installed. But that PSU was well designed, and just refused to turn on under inappropriate load conditions. The real danger here are the units that will happily turn on despite the voltages being totally out of whack (I wouldn't be suprised if the PG line was tied directly to +5V on those specimens).
retardware wrote on 2021-09-06, 18:26:Or, use 25V caps instead of 16V ones...
Yeah, if I had to use tantalums I would definitely go with 25V caps, especially for 12V and -12V. If there's something tantalums doesn't like is when you go over the rated voltage, so that would at least add a layer of safety.