8mm Forum: bolex paillard 18-5 electrical question

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Posted by Steev Hise (Member # 3955) on September 27, 2013, 08:33 AM:

Hi,
I have a Bolex Paillard 18-5 8mm projector that I recently broke, but I'm not sure what happened and I'm hoping someone here might have some insight. The power socket on the back was loose because, I deduced later, the screws holding it in had been loosening, and when I pulled the cord out, the whole thing came out. This might have been a minor thing except that stupidly, I had not unplugged the other end of the cord from the wall socket, and there was a spark. After that, the projector didn't run. I at first suspected it was the fuse, but after replacing it, still nothing, so I fear that some other component blew out during the electrical arc. maybe the power transformer or something. One mystery though, is that when I look at the socket, there are 2 terminals, and one terminal has wires soldered to it, but the other has nothing connected, just a glob of solder. I don't see any dangling extra wire anywhere, so my guess has been that when the socket is in place the terminal is intended to make contact with the metal body of the projector, which is the common ground, and complete the circuit that way. But, I don't know that for sure and maybe there's supposed to be some other wire that connects that somehow fell back inside and i don't see it. Does anybody here know? Does anyone have a schematic? Any advice on what else I can try or what part most likely blew and whether it's realistically replaceable?
Many thanks,
Steev

Posted by Maurice Leakey (Member # 916) on September 27, 2013, 10:25 AM:

If there is a "glob" of solder then there must have been a wire connected to it. The metal cover probably connects to the metal body for earthing (grounding) but would not connect to your neutral.

Keep looking!

Posted by Steve Klare (Member # 12) on September 27, 2013, 11:21 AM:

My theory is when that terminal touched the case, the heat from the short circuit melted the solder and then the wire fell off.

I think if you open the machine up you will find your wire disconnected inside.

I hate to think of the body of a metal device being used as neutral, but with old hardware you never know. What that means is if somehow hot and neutral are flipped or neutral is interrupted someplace else (like someone adding a new switch into neutral instead of hot) neutral at the machine is now hot and will deliver a jolt to the poor sap that touches it and ground at the same time.

These days neither hot nor neutral is connected to frame. They are isolated and the frame is grounded. Neutral and ground aren't the same. Ground just runs to earth, neutral carries current. If more than a trickle of current flows into ground, that's usually a bad thing!

Posted by Steev Hise (Member # 3955) on September 28, 2013, 01:36 PM:

Wow thanks Maurice and Steve for your help. It's been so long since i thought very hard about electrical stuff that I guess I forgot my good sense.
I ended up taking the thing apart a little further, and although there's big metal structural bits that made it difficult to see, I eventually did find a little, frayed, uninsulated wire hanging there unconnected on one end. after more careful futzing I managed to solder that back to the power socket. then the ceramic socket crumbled as i tried re-seating it, and i had to rewire everything to a new power cord, but eventually got it all working again. Thanks again for the advice!

Posted by Maurice Leakey (Member # 916) on September 28, 2013, 02:03 PM:

All's well that ends well! Good show.

Posted by Steve Klare (Member # 12) on September 28, 2013, 02:36 PM:

No problem!

Lambda Electronics used to have a factory at the corner of West Drexel Rd. and Calle Santa Cruz.

I haven't done any electronics in Tucson since they closed it in 1997!

Posted by Paul Adsett (Member # 25) on September 28, 2013, 03:44 PM:

Incidentally, the control knob on my Bolex 18-5 still glows in the dark 50 years after this projector was manufactured! [Smile]

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