Mini Chopper Designs

Changing the startup problem source of the power circuit?

I'm repairing a power unit. It's high voltage DC circuit @ 320VDC. There two chopper supplies. The 12 VDC is the main output. The 20VDC is for the chopper circuit, a chip TL494. All good for testing semi Ohm meter. No The TL494 Vcc while connected so you never run the helicopter. I can "reactivate" the TL494 momentarily applying Vcc external 9VDC and GRND. The source works well w / battery or after that until disconnected. Brand: Hanny Model: FX-101 schematic or tech support not available. The problem is initial implementation. Hanny How to design the launch of their deliveries to the change? Is the offer of a mini linear? An output resistance? A cap of departure? Self resonance? What should I consider? Selected power resistors, all within the specifications. What I can search? The offer is only five months old, it is unlikely caps dry. Ideas?

I'm not familiar with this special offer, but not Vdc pulse width modulation chip things usually do not run. There must be a power source Vcc is missing somewhere. The data sheet shows that the TL494 Vcc (pin 12) should normally be 7 to 40 VDC. The total supply current is approximately 5-10 mA for this chip. You might use a voltage divider of the 320 VDC for power. Look for two resistors connected the Vcc pin (or lack or burned). You can find something in the data sheet that matches your circuit, so … hard to diagnose without more information or to see for myself.

NWCC08 Mini Chopper