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AuthorTopic: How well are the MeanWell RT-50b PSU regulated?  (Read 566 times)

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Offline brostenen

How well are the MeanWell RT-50b PSU regulated?
« on: February 12, 2019, 03:51:44 PM »
Hi all.
Anybody know anything about how well an MeanWell RT-50b are regulated on the output lines? I have seen a lot of people using them, yet nobody is talking about if there is a potential risk of frying an Amiga500, 600 or even an 1200 when it goes under heavy load. Yet I have seen a talk about people recommending to avoid an ATX psu, because of poor 5v regulation.
 

Offline mechy

Re: How well are the MeanWell RT-50b PSU regulated?
« Reply #1 on: February 13, 2019, 04:34:55 AM »
Most All switching power supplies are regulated. I think you mean does it have over voltage protection. The Meanwell rt-50b does have over voltage protection. Its over voltage that can kill your Amiga,C64 etc.
Generally poor 5v regulation will just sag on the 5V rail going low,not high in most cases.
Low voltage generally will not do any damage.
For example,4.9volts wont hurt anything,but 5.4volts could start killing parts. I've seen a4000's that will not reliably boot at 4.92v.
 Plus or Minus 5% is usually acceptable on 5V rail.
Most modern ATX power supplies regulate poorly on the 5V rail because pc's have moved to using 3.3V and 12V mostly.
Some ATX power supplies need a good load on the 5V rail to regulate properly.
If in doubt check the datasheet for the power supply in question,it will usually tell what protections it has.
 

Offline brostenen

Re: How well are the MeanWell RT-50b PSU regulated?
« Reply #2 on: February 13, 2019, 09:27:33 PM »
Thanks.
Seems as these Meanwell PSU's are a solid choice for anything 80's and early computers.
 

Offline dalek

Re: How well are the MeanWell RT-50b PSU regulated?
« Reply #3 on: February 14, 2019, 01:13:40 PM »
The main thing with these is that most Amiga's draw only a small amount on the -12V line.  If you check the meanwell rt-50b datasheet there is a minimum current requirement of 0.1A (which is not too bad).  On other meanwell models the minimum requirement can be higher, like 0.5A.  Personally for 0.1A I add a power resistor across the -12V line to ensure it is drawing the minimum (e.g. 120R 2W or bigger like 5W to handle more heat).  I've found this can stop the hum or whine you may get.  I've never checked on a scope to see how much difference it makes.

But there are plenty of folks out there using them without fully loading the -12V line with no noticeable issues.
« Last Edit: February 14, 2019, 01:16:34 PM by dalek »