Power Supply with transformer 300V

Not likely that freq is problem

More likely:

The power supply expects a load at the output that will drop the voltage or

There is a control circuit at the output that feeds back to control the voltage and the feedback control is not working.

Dan

Dotinho wrote:

I have seen a few circuits that do preliminary regulation by switching the supply voltage like that, but usually SCRs or triacs are used, so it might be a good thing to double check not only that part but everything around it. Do you have a schematic; if not, scribble one up aqnd document each part as best as you can. Check each part to see if they are within spec, especially that "MOSFET". I am guessing that the "MOSFET" is always on, and that the second transformer sees the full 300V sinewave from the first one. Then again, you did say 315VDC, which (to me) means that the circuit may be closer to what i had seen. First is a transformer, Primary: 220VAC,Secondary: 300VAC. Second is most likely a bridge rectifier where at least 2 components are SCRs that are switched, allowing the output to be adjusted from zero to 315VDC. Now it is possible that 4 diodes are used and a MOSFET is in the bridge acting as a series adjustable resistor to the "load", but that useage (as a series resistor) is extremely unlikely to say the least. If indeed it is a MOSFET, it most likely is used as a timed and synchronized switch to the load and there is no filtering on the 315VDC source (might be some at thhe load). So now one has a semi-regulated and adjustable DC to feed some kind of a load. It is not clear as what that load is; surly DC *cannot* be applied directly to a transformer! Usually, that DC is used to drive a switcher that drives the second transformer, and the second one is dinky compared to the first transformer. That was done in a high votage bench supply that was precicely (via a helipot) adjustable from 0 to 3KV (i think; it has been over 30 years).

Maybe what the layout is like the following: First is a transformer, Primary: 220VAC,Secondary: 300VAC. Second is most likely a bridge rectifier where at least 2 components are SCRs that are switched, allowing the output to be adjusted from zero to 315VDC. Now it is possible that 4 diodes are used and a MOSFET is in the bridge acting as a timed and synchronized switch to the load (second transformer). So now one has a semi-regulated and adjustable AC to feed that transformer.

No matter what the case is, it is clear that the switching components (SCRs, Triacs, MOSFETs) are "shorted" and thus the full sine wave is being applied to that second transformer.

Thats true, but the transformed are mailfunction, becoused i already tested the other part, and that tranformer don't produce anymore, and i'm trying to get another solution, you understand?

thanks..