Lambda Vega 450 or similar schematic needed

Hi all,

Could someone please share a schematic for Primary side of TDK-Lambda Vega 450 (or similar version) PSU please?

There were some old topics here when someone said they do have schematics, but those topics are closed now. Hopefully the diagram is still available.

Many thanks.
Greg

TDK-Lambda 450 startup

Hi all,

Asked here for a schematic before, but no reply.

Does anyone know how the startup voltage circuit is designed in the Vega 450 PSU (or similar) please?

When powered from mains - I do get voltage on filter caps and a startup voltage on UC3842 around 13V, but it may be too low. There should be another voltage (around 16V I guess) to power a PFC L4981 and some other ICs (LM393 and a few more) which is not present at the moment.

Powered the 16V only (no mains) from a bench power supply and there is no shortage there (around 70mA current draw which seems normal)

When powered with mains voltage, 16V Dc from an external PSU and with PWM IC un-soldered - the PFC circuit kicks in as I get around 375V Dc on the filter caps and it's independent from a mains voltage from an adjustable separation transformer.

The PWM start-up voltage goes through a common cathode dual diode (anode 1 is that 13V voltage I get, anode 2 should be 16V).

Any help would be much appreciated.