8mm Forum: Bolex 18-5 super - no power to bulb.

This is topic Bolex 18-5 super - no power to bulb. in forum 8mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=008634

Posted by Jon Byler (Member # 3933) on October 05, 2013, 11:29 PM:

I have yet another projector problem... Thankfully there are one or two that run always!

My Bolex 18-5 super is functioning properly with new belts, but I can't get it to light up. I took a bulb that I know is good from an 18-5 regular 8mm machine and it wouldn't light in the super. I checked with a multimeter and got no voltage at the lamp base either. A resistance check shows that the switch is at least nominally functioning, as it shows open when the machine is in a "lamp off" position, and shows a small resistance between 4 and 10 ohms in the various lamp on positions. I haven't traced the circuit back yet to the transformer as I don't have the proper wrenches at home right now to take the cover loose.

Has anyone experienced a similar problem? I seem to be really unlucky and machinery finds new and interestingn ways to break or fail just for my benefit. I really hope I can find a solution as this seems like a really nice machine.

-jon

Posted by Steve Klare (Member # 12) on October 06, 2013, 04:21 PM:

You should be able to poke an ohmeter into the two terminals of the socket (power off!) and see a low resistance when the bulb should be "on" and open circuit when it should be "off". If you see "open" all the time you probably have a disconnect. If it looks OK then no power is coming out of the transformer.

If the 4 to 10 Ohms is real that's a lot. A 50W, 8V bulb is a little more than an Ohm. With 4 to 10 Ohms in series, you probably shouldn't even expect "dim", but this may just be a film on the contacts that will break when you put some energy in the circuit.

It's seeing zero volts on the socket that's the real sign of trouble. 4 to 10 Ohms is nothing compared to the 10 million ohms a decent voltmeter is.

Posted by Jon Byler (Member # 3933) on October 06, 2013, 04:41 PM:

Hi Steve,

My tests were without a bulb in place. When switched "on" it showed some resistance that I imagine is the resistance of the transformer coils. I've got to go to my office and find my tiny wrenches that are for setting the points in distributor caps on cars to be able to to take the cover off the transformers.

Showing zero volts on the socket when powered up in all positions. I'll have to look and see if I can find an electrical schematic for it, trouble shooting is much easier with one of those.

Posted by Leon Norris (Member # 3151) on October 21, 2013, 01:28 PM:

hello Jon my name is Leon Norris of Leon's Projector Repair if you would like your projector fixed you can ship it out to me but email me back and let me know thank you Leon Norris

Posted by Jon Byler (Member # 3933) on October 21, 2013, 05:27 PM:

Thanks for the offer Leon, but it's probably not worth it for me to send off for repair. There are enough cheap ones out there that I can take parts from that I'll get it fixed eventually.

Posted by Niels Peter Buch (Member # 3757) on October 31, 2013, 06:44 AM:

Hi Jon.
I had a similar problem with my Bolex 18-5 .
Cleaning the brass contacts behind the shifter (forward/backwards).
solved my problem.

Best regards

Posted by Jon Byler (Member # 3933) on November 02, 2013, 08:04 PM:

Thank you Niels, I'll check that out.

UBB.classic^TM 6.3.1.2