8mm Forum: EUMIG MARK 8 HELP - LIGHTING ISSUE

This is topic EUMIG MARK 8 HELP - LIGHTING ISSUE - HELP in forum 8mm Forum at 8mm Forum.

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Posted by Kaz Takagi (Member # 5009) on September 12, 2015, 08:57 AM:

I hope everyone is having a good weekend. This is my first post so I apologize in advanced for any mistake.

I have a EUMIG MARK 8 (unit A) that I am trying to repair. Finally got the forward and reverse running smoothly again but there is NO light when I flip the switch. Check the wire continuity, socket voltage, bulb continuity and there is absolutely no problem. Even take this socket and put it in another Mark 8 (unit B) and it is working fine. Just unit A that I am having problem with.

I am NO electrical expert but is willing to take a couple of electrical jolts to get this unit going. I see some small circuit board with wiring but have absolutely no idea where to begin. Any helps are most appreciated.

Thank you very much for your help in advanced and have a good weekend.

Kaz.

Posted by Maurice Leakey (Member # 916) on September 12, 2015, 10:55 AM:

This is an old projector, perhaps the lamp socket's "holes" have corroded.
A new socket may provide a solution.

Posted by Steve Klare (Member # 12) on September 12, 2015, 11:40 AM:

Welcome Kaz,

The lighting circuit is all low voltage: no jolts required!

Measuring the socket voltage can be deceiving. Let's say there is enough resistance in the circuit to keep the lamp from lighting (....did you say it?!). If you hang a voltmeter on the socket the resistance of the meter is very, very high (usually 10 Million Ohms) and the tiny trickle of current through the bad connection will make a voltage drop so small that it will look like the full voltage is getting through.

Now you hang a lamp on there (<1 Ohm) and the large current through it makes a big voltage drop where the problem is, so you get no power in the lamp.

I'm thinking you have some flaky contact somewhere and if you start measuring voltages between the transformer and the lamp you'll find that 12V is showing up someplace that isn't the lamp!

Good bets: lamp switch, electrical connections, maybe wiring.

I'd bet on the socket itself if it didn't work after you transplanted it.

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