Electronics > Beginners
Cheap chineese power supply missing short-circuit protection
<< < (7/8) > >>
schmitt trigger:
I have mentioned that previously I worked at a large PSU manufacturer.

This is Deja Vu..............What I see here is something that we saw a couple of times. A Chinese hacker would take one of our designs, proceed to "Muntz it" and then start making replicas with the exact same board artwork minus a lot of components or with lower-rated components.

Of course, those could be sold significantly cheaper.

My two Yen on reliability on this particular PSU: Modify and test it.

A simple and very bare setup:  Let it cook at full load, fully fuse-and ground fault protected, inside a metal box.  The metal box will allow the temperature to rise (have a thermometer monitoring it so it does not rise that much) and catch any flying debris or flames.
As long as you use power resistors as a load, nothing will happen to the load.

If you have access to a Variac, apply at intervals full rated AC input voltage, followed by the minimum AC input voltage.

Leave it on over the weekend. When you finish, if the unit is still working look around for signs of discoloration on resistors, brown markings on the board, or bulging electro caps.

dominicM:

--- Quote from: glarsson on May 15, 2018, 01:29:11 pm ---Some cheap power supplies fail by leaking high tension from the primary side to the secondary side through a poorly designed transformer (not enough insulation, improper construction, overload damage,...)

You defend this trash power supply against all comments - why?

--- End quote ---

I am not defending it. At most I am making a point that cheap stuff has it's place. If it is reasonably safe that is, hence the discussion. The problem with decent PSUs is that they seem to be unreasonably expensive (even compared to high end PC supplies) and harder to source at times.
dominicM:

--- Quote from: schmitt trigger on May 15, 2018, 01:33:00 pm ---I have mentioned that previously I worked at a large PSU manufacturer.

This is Deja Vu..............What I see here is something that we saw a couple of times. A Chinese hacker would take one of our designs, proceed to "Muntz it" and then start making replicas with the exact same board artwork minus a lot of components or with lower-rated components.

Of course, those could be sold significantly cheaper.

My two Yen on reliability on this particular PSU: Modify and test it.

A simple and very bare setup:  Let it cook at full load, fully fuse-and ground fault protected, inside a metal box.  The metal box will allow the temperature to rise (have a thermometer monitoring it so it does not rise that much) and catch any flying debris or flames.
As long as you use power resistors as a load, nothing will happen to the load.

If you have access to a Variac, apply at intervals full rated AC input voltage, followed by the minimum AC input voltage.

Leave it on over the weekend. When you finish, if the unit is still working look around for signs of discoloration on resistors, brown markings on the board, or bulging electro caps.

--- End quote ---

Not sure how useful that would be. I am already working under assumption that it is unreliable (with or without missing components). If it fails I can just replace it, it's not critical. Issue is with safety, including to a small degree components attached to it.

I would never run these cheap PSUs at full load anyways, if I actually needed a 400W I would try to go with 800W PSU. It also has a fan so heat is probably not going to be an issue here.
schmitt trigger:
Hmmmmmmm.............

Looking at your schematic, where is the bootstrap circuitry?
For startup purposes.
dominicM:

--- Quote from: schmitt trigger on May 15, 2018, 06:11:15 pm ---Hmmmmmmm.............

Looking at your schematic, where is the bootstrap circuitry?
For startup purposes.

--- End quote ---

It's not my schematic I just linked to it. It's also traced so irrelevant parts may have been left out. There is no better datasheet as far as I know.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod