Jet Engine Igniter Box

A microwave oven diode would probably do the trick.

Is this for a manned aircraft? If so then I'd hesitate to make any sort of substitutions even if they're likely to work fine. There's a lot of regulations surrounding that, and for good reason.

It's for ground use only. The microwave diode is a good idea, what is the rating for these? Any other suggestions of common faults with igniter boxes, I'm only guessing it's the rectifier, haven't made any checks yet.

A common rating is 12KV 500mA, I've never worked on one of these boxes but I'd start by checking for bad solder joints and then check any generic semiconductors, it sounds like a pretty simple device. If you happen to be near Seattle I'd be happy to take a look at it just to dig into something I've never seen before.

}I need to fix an igniter box, I suspect it might be the high voltage }rectifier, what modern equivelent could I use for the rectifier diodes? }The box is a rotax type NB 25/3, 24 volts in, 2kv out, 12 joules. }It's a simple circuit comprising of a trembler mechanism, induction coil...

The simplest test would be to check the primary & secondary of the induction coil for continuity. Have you?

Stan.

The primary is .5ohm, the secondary+ diode is 6M. I removed the high voltage cap and is measures zero ohms.

Sounds like that's your problem then. The cap should measure open circuit.

Amen to that except: If it is an electrolytic cap, resistance will be in the megohms after it stabilizes, but *not* 0. If it is a film cap, then resistance should be as near-infinite as matters, but again

One last thing, if this is an electrolytic cap, make sure it doesn't bite you. Discharge it before handling it.

Peter Wieck Wyncote, PA

In message , " snipped-for-privacy@aol.com" writes

Discharge any caps that are used in high voltage/energy circuits, they don't need to be electrolytic to carry a nasty amount of charge.