Eiki hum

[Jason Moffatt]

I now have quite a few eiki elf projectors M, ST/M, RT and NT models. All the RT and later NT ones i have seem to have hum coming from the machine itself rather than the speaker when plugged in but the earlier M and ST/M models don’t.Any reason for this ?.

[John Burgess]

The hum is probably coming from the transformer, this is quite normal and nothing to worry about. Some of my machines have a similar hum and are still going well.
John

[Maurice Leakey]

Further to the comment from John.
The early models M & ST/M use a 200 watt lamp as against the later models which use the 250 watt lamp.
No doubt the early models have a different transformer.

[Nantawat Kittiwarakul]

I can only confirm that my NT-2 projector, even with later serial no. (5**** or something) DOES hum a bit also. Usually it's not that very audible - you wouldn't hear it unless you're sitting right besides the projector.

However since I had rerouted the internal wiring somewhat so that the drive motor will be directly driven from ac mains instead via the transformer. When I only need the film transport part to work and not the lamp/amplifier section (telecining silent films, for example) I can just plug in only the motor section, so it'd be very quiet to work with.

[Steve Klare]

I agree with John,

The first time I powered up my first 16mm machine I heard a decent amount of hum. I held the speaker to my ear and didn't hear it there.

-all from the transformer.

Other than listening to the audio through headphones, there wasn't a whole lot I could do about it either!

[Jason Moffatt]

Yes it is more noticeable on some than others. I want to sell one of the RTs which has quite a bit of hum and will have to explain to the buyer that this is normal. Is there any way of reducing it ?.

[John Burgess]

Jason, you could check the transformer is fixed down firmly ,apart from that there is really nothing else that will stop this hum.
John

[Jason Moffatt]

Yes i made shure the transformer was not loose. So would these have always had this hum even when new ?.

[Ken Finch]

Whilst not being an expert in electronics and repair of amplifiers etc. my father was and I did pick up some knowledge from him. He would have said that all transformers hum. It is the ac frequency of 50cps in the U K. and is quite normal and some are louder than others. As has already been suggested some are louder than others, and much depends on mountings and positions which can act as an acoustic amplifier. Ken Finch.