Transformer-Variable Power 28Vdc OECO

[blueskydriver]

Hey Everyone,

I got an issue with wiring up a Transformer-Variable Power to the reading light. The issue is, how is this wired?!

First, the transfomer is used to dim the reading light (B707 or B727). It is made by OECO Corporation and is PRI 28V 400 CPS, SEC 0-28V 6 AMPS.

It has three connection pins 1 HV (high voltage) 1 LV (low volatge) and 1 G (ground). When I disconnected it from the light (for painting the housing), the HV was going to bulb inner metal tab and the LV was connected to the bulb outer metal tab. The G was not connected to anything.

Second, I have a 110 Vac power supply that puts out 24Vdc at 1A. I tried this and the transformer has no effect on the bulb when I turn the knob in either direction. I did check the bulb alone to make sure it lit up and it does at 24Vdc.

Finally, I know it is 28Vdc for the power transformer, but does it actually have to get 28Vdc for it to work and what is the correct way to connect this up? If you have a postive and negative from the power supply where are they going if the bulb is connected to HV and LV? Better yet, give me an education on this...

John

[Michael Carter]

It's not working, because it requires AC voltage to operate. DC voltage has no frequency, and your unit is clearly marked 400 CPS, which is AC aircraft frequency.

These light dimmers are fed power from the Essential 28VAC buss. Without a schematic I don't know whether they invert the incoming AC to DC to light and control the lamp intensity.

I wrote to OECO with a request for information about these dimmers for you. I'll let you know if I receive a reply.

[Michael Carter]

I received a reply from jeffm@oeco.com this morning. He states in all probability it is an AC powered dimmer.

He asks if there is a data tag with a part number to be sure. If you have a part number post it here and I'll check back later.

[blueskydriver]

Michael,

Thank you for contacting the company for me. I really appreciate your help with this. There is a part number and it is: P/N 6430A

Thanks again,

John

[Michael Carter]

Thanks. I'll relay that info for him.

[Michael Carter]

He e-mailed me back a little while ago. They are officially closed this week, but next week he said he would pull the related document for me and send it to me.

Nice of him to take care of business on a day off today.

I'll let you know when I receive it.

[Rodney]

Michael,
Anything new here?

[Michael Carter]

Yes. I have a .PDF for you. PM me your e-mail address and I'll send it to you
Tonight when I get home from work.

BTW, they are AC powered @ 400hz.

[Rodney]

BTW, they are AC powered @ 400hz.

Crap, I was afraid of that. Weird though as the backlighting is 5VDC. Will PM you. And Thanks!