ebay power supply

[John S]

So after the sage of parcel farce, parcels 2 go etc was it possible to get to around the 40 volt mark ?

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[irving2008]

So after the sage of parcel farce, parcels 2 go etc was it possible to get to around the 40 volt mark ?

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Still working on it John, looking promising but haven't had much time this week...

[HankMcSpank]

Still working on it John, looking promising but haven't had much time this week...

Old thread - what was the outcome? (did anyone manage to tame the voltage?) The seller is still knocking these out at £12.99 per PSU (his wife must be a tad miffed at them laying around the house by now!) ....


http://cgi.ebay.co.uk/NEW-UNUSED-50V...item587e03d24d knockout price.

[irving2008]

Old thread - what was the outcome? (did anyone manage to tame the voltage?) The seller is still knocking these out at £12.99 per PSU (his wife must be a tad miffed at them laying around the house by now!) ....


http://cgi.ebay.co.uk/NEW-UNUSED-50V...item587e03d24d knockout price.

I managed to blow one up and to fry the input of my PicoScope.... (cost me £300 to replace it :sad: ) due to selecting a reference point that wasn't the ground potential I thought it was!

The problem is that the design doesnt directly match the reference application schematic for the controller chip, and has a third-party board full of SMT parts that appears to do the opto-isolated feedback with at least one custom chip on it... Also there appears to be three power supplies in there, the main 50v job from a 400vDC rectification and two others, one of which is a -ve rail.

As we know there is a input pin who's voltage controls the output. This goes into the SMT board and I believe this voltage drives a current source (as per the reference model) that controls the feedback circuit, however I was unable to identify that part on the board and suspect its inside the custom chip. Also there is obviously some sort of comparator on it to drive the 'in regulation output and control the current limit' but again suspect this is inside the custom chip too.

The result of all of this is I was unable to find an easy way to change the control range. I believe the necessary resistor(s) to change are on the SMT board but I cannot yet identify them. And then other pressures overtook the time I had available...