8mm Forum: EIKI (Elf) Projector Amp Hum

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Topic: EIKI (Elf) Projector Amp Hum

Phil Clarke
Junior
Posts: 26
From: London, United Kingdom
Registered: May 2014

posted October 01, 2018 04:11 PM

Hello all

I'm currently fixing up an EIKI/Elf ST projector I was recently given, and I have one task left: the whopping amp hum that starts up whenever the lamp and/or motor are running.

The hum goes away when you plug in a mic to the amp, and you get normal sound. So I'm figuring this is probably dodgy shielding or capacitor/s.

Just wondered if anyone here has seen this issue before and can advise where to look. I have a second donor machine available for parts if needed.

cheers
phil

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007

posted October 05, 2018 06:05 AM

Phil

I'm no mechanic so my knowledge is somewhat limited.

That said, it sounds that extraneous light is somehow reaching the solar cell, perhaps the light shield is not in its correct position.

However, this might occur when the lamp is on, but you say that this also occurs when the lamp is off.

I assume that part of the circuit is by-passed when you plug in the microphone, so it seems that the problem might be in the early stage of the amplifier.

You can download a service manual of the Eiki ST/M on this website, perhaps it may assist you.

http://www.film-tech.com/warehouse/index.php?category=2#16mm Projectors

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Maurice

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Jonathan Wood
Junior
Posts: 17
From: Oxfordshire, UK
Registered: Oct 2018

posted October 06, 2018 01:53 AM

Hi Phil,

If it’s a very loud humming as opposed to the usual hum you get when you just crank up the volume without a film playing and if you only hear it once you either start the motor or switch the lamp on , then it sounds like a grounding issue to me ? Have you checked all the relevant wiring to make sure the insulation is ok and not touching something it shouldn’t be ?
Cheers , Jon

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