SP-PW1-10 (Metcal SP200 power supply) schematic and BOM

[t0m]

I found this schematic floating about on the web, and decided to compare it against the PCB of my recent fleabay purchase.

I verified that pin 4 of the UC3823N is not connected to ground, as noted here.

On my PCB, capacitor C5 was omitted and the integrator C3 had a slightly different value.

The schematic omitted the EMI filter. It also omitted the green LED that illuminates when the unit is switched on, the anode of which connects to U2 pin 12 via a 330 Ohm resistor.

[t0m]

I'm pretty sure the big chokes are wound on T106-2 cores.

Brian Dorey has the power FET as IRF840.

More pics here and here and here.

[quadtech]

Brian Dorey[/url] has the power FET as IRF840.

And I thought "Magic Smoke" was copyrighted by a certain Dr Price.   

[t0m]

I am confused by the top rail being +50V. As I understand it, the transformer is rated 115VAC 36VCT meaning that it outputs 36VAC between the end terminals. After full wave rectification with a bridge diode and smoothing, I would expect a maximum potential of 36VDC minus 2 diode drops. 

[oPossum]

36 volts RMS has a peak of 50.9 volts.

[oPossum]

So you get 50 VDC from 36 VAC.

[t0m]

Do you though? With a nonzero load?

[oPossum]

With no load it will probably be a bit higher.

[t0m]

OK thanks, I learned something.

[mwb928]

Hi,

I would like to have the procedure to adjust the "current adjust" and the specified value.

Thanks a lot.