Circuit Diagram/Schematic for HCSA-200

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Andy2k3

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I have a SMPSU which controls a height adjustable desk. input 230V AC, Output 24V DC.

The PSU died. Symptoms: just blew fuse in mains (230V). As the mains is a bit dodgy sometimes I replaced fuse - symptoms the same.

Internally the PSU has a lot of yellow potting compound on many components, which is a pig to deal with.
Board is made by NAO technologies, board number HCSA-200 Rev A.
One resistor (PR2) (looks to be a half watt size) shows heat damage around the potting compound, but as I have no diagrams find it difficult to start diagnosis.
Emailing company has no reply.
Anyone have any experience with this? Anyone have any schematics/circuit diagrams?
 
If the mains fuse blew, then you should check the Mosfets, rectifier diodes, and the main smps control chip.

It looks to me that your power supply is a SMPS, or a Switch Mode Power Supply.
Unfortunately, these SMPSs are very complex!

P.S. It is helpful to post some pictures too
 

Thanks - as noted in my original post it is indeed a SMPS, and checking stuff in-circuit is not the easiest thing to do when I can't input AC, and half the components are under potting compound.
I've managed to find a few datasheets for individual components, but it looks like I may have to do it the tedious way and create a circuit diagram myself
 
It is lot easier to buy a DC24V SMPS off the shelf because it is cheap and saves you big time & trouble of an adventure with less hope for success.
 
sansgp said:
It is lot easier to buy a DC24V SMPS off the shelf because it is cheap and saves you big time & trouble of an adventure with less hope for success.
Click to expand...

Thanks for the reply, but this is a 24V 8 Amp supply, so not so cheap to replace.
I have dismantled some of the PSU, having spent ages getting rid of most of the potting compound.
I had to dismantle it to get to the component I suspect - the damn potting compound had caused one of the power resistors to fry).
Whether that is the underlying cause is unknown, but at least I can start to troubleshoot properly; first job is replace the resistors and put it under load.

I created a circuit diagram, the only thing missing is the internals of the IC, but I think I found a suitable equivalent I can look at.
 
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