Need some help identifying several power supply capacitors that are
blown, inside a 200V DC power supply. The caps are axial (Poly film?)
and are labeled 103KV 630.
What are these? They are mounted across what appears to be a darlington
103k means 10nF or 0.01uF
IIRC the k means +/- 10%
630, maybe 630 voltage rating depending on the topology of your power supply
and where they are in the circuit. It could well be 630V seeing it is a
These Are 10000PF Capacatiors (103) used as snubbers and depending on what
is connected to the Darlington configuration they may be film but my guess
would be paper to prevent power up surges that would POP the Collector
Emitter junctions since they are rated for 630 Volts in 200 VDC supply.
Paper caps would be hard to find these days but you can use a Mylar film
type to replace them. If they went more than likely your Darlingtons were
cooked. Check the surrounding circuitry there was a reason they cooked. Good
A few more details. I don't think they are Darlingtons. According to a
service tech, they are 3 phase bridge rectifiers instead. There is
continuity (.4V drop) BOTH directions, tested in-circuit. So that is
probably bad news.
The Line voltage measures 250V, the wild leg on the rotary phase
converter measures 260V. The machines are rated for 208V, so that is bad
too. (working to resolve that) The paper/film caps are rated 630V DC,
250V AC, so that answers one of the failure questions. t
The have been running at 250V-260V for five years.
How do you size buck-boost transformers? Load KVA x Voltage drop% =
Veriz> These Are 10000PF Capacatiors (103) used as snubbers and depending on