Film-Tech Forum ARCHIVE: Kelmar Series IV automation microswitch question

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Posted by Frank Dubrois (Member # 3042) on 09-05-2007, 12:42 AM:

These switches seem to be going out quite frequently. Does anyone know which switch controls what in the automation? My next question is, does it even matter? If one switch (say the 4th one in) goes out, its best to just replace them all up to that point? I'd really like to find out what switch controls what function in the automation, and to this point, can't seem to find that info anywhere. Can anyone help?

Posted by Mark Gulbrandsen (Member # 72) on 09-05-2007, 08:42 AM:

Just replace em all when you pull the cam timer out. Its a very easy job to do and inexpensive. I also reccomend that you place a line down all the cams with a sharpie so you know if you've disturbed any of each cam's settings when its re-assembled. When disassembling be sure to lay the pieces out in the order they came off and then just reverse that order to put it back together.

Expect even less life out of new micro switches and relays since the lead free act took place.... there is now no cadmium in any new contacts [Mad]

. They now drop like flies and will continue to do so. I feel that with the days of lead free being upon us or at least until suitable substitutes are found for the metals that were once used that electromechanical automation is pretty much at its useful end.

Mark

Posted by Steve Guttag (Member # 268) on 09-05-2007, 08:48 AM:

You know, they could always start "gold flashing" the contacts for the lesser current switches!

Steve

Posted by Mark Gulbrandsen (Member # 72) on 09-05-2007, 08:59 AM:

Not even gold would hold up on the AC connected contacts of switches and relays for very long. Its too soft, would be extremely thin and each arc generated when the contacts open back up would erode it away in no time. It would be good for contacts on anything below about 12 volts and very low current. The only thing that will hold up really well and even better than the original are solid platinum contacts but thats too pricey for mass production. I am hoping that some substitute metal will ultimately be developed that will last... they just haven't found one yet.

Mark

Posted by Louis Bornwasser (Member # 3063) on 09-05-2007, 12:38 PM:

Most major suppliers have stopped making cam timers. Louis

Posted by Mark Gulbrandsen (Member # 72) on 09-06-2007, 09:10 AM:

Indeed there are a couple of options available that are mpu based to repace cam timers in existing units but that still doesn't solve the relay aspect of the problem.

Mark

Posted by Monte L Fullmer (Member # 2797) on 09-06-2007, 12:24 PM:

Isn't there a resistor (or cap) value that one can put across each micro to reduce the current rush so the contacts inside the micro can last longer?

Posted by Mark Gulbrandsen (Member # 72) on 09-06-2007, 06:12 PM:

Monte... Its called a snubber.... usually made up of a 10 ohm 1/2 watt carbon film resistor and a .1uf 1200 volt cap in series.

Mark

Posted by Marc Hansen (Member # 705) on 09-15-2007, 06:14 PM:

quote: Mark Gulbrandsen
Indeed there are a couple of options available that are mpu based to repace cam timers in existing units but that still doesn't solve the relay aspect of the problem.

Mark

How expensive are they and where are they availible?

Marc

Posted by Mark Gulbrandsen (Member # 72) on 09-15-2007, 08:43 PM:

Any Honeywell switch distributer should stock em. You definately need to get an exact relacement so the nylon conector hooks on correctly!! We get em in at least 100 quantity.

Mark