Film-Tech Forum ARCHIVE: EPRAD Problems

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Posted by Steve Anderson (Member # 364) on 02-03-2004, 10:18 AM:

Ok here is the problem.
We have an EPRAD Co-Operator system (early 70’s)

When the operator tried to start the film and the system tried to fire the lamp it would trip the breaker on the rectifier and the house breaker. I came in this morning and found that the Slide switch (left side) was burnt and when I tried to fire the lamp manually there was a nice arc coming off the switch. It had also burned out the fail safe in the lamp house (small wind vane type for the internal fan) So I bypassed the fail safe and tested again, a nice arc again from the switch. I have unsoldered the wires going to the switch and this eliminated the problem but now I do not have any fail-safes operational. So my question is on the switch in the schematics I believe the problem is at the SW-1 terminals 6 and 7, which is the rectifier relay. I will have to replace this switch but is there anything I should check coming from the lamp house that could cause the switch to arc and burnout?

Posted by Gordon McLeod (Member # 33) on 02-03-2004, 04:18 PM:

What make of lamphouse rectifier as there sailswitches may be wired differently brand to brand
The switch in the cooperator probably started to arc and then shorted

Posted by Steve Anderson (Member # 364) on 02-03-2004, 06:39 PM:

We are running a XH-XeTRON 3K Lamphouse.Also a IREM rectifier.

Posted by Rick Long (Member # 213) on 02-03-2004, 11:05 PM:

And, we are assuming this system has been working properly for some time before this?

Posted by Steve Anderson (Member # 364) on 02-03-2004, 11:13 PM:

No problems in the last 2 years that I have been there.

Posted by Rick Long (Member # 213) on 02-04-2004, 09:26 PM:

According to the manual, terminals 6 & 7 are "dry contacts" (funishing no external voltage), in other words a set of relay contacts, paralleled by a switch. Unless you see carbon tracking from either the relay socket or the switch that could shunt current to ground, I doubt that this is the cause.

Posted by Paul G. Thompson (Member # 655) on 02-04-2004, 09:28 PM:

Me thinks you might have a rectifier problem if you cannot get the lamp and rectifier running manually. Since it is presently unknown what type of lamp and power supply you have, I find that a dark area for suggestions.

However, most lamps and power supply set-ups have provisions for manually firing the lamp in event of an automation failure.

It has been my experience that the Co-Operator leaves a lot to be desired, but when they work properly, they are really not that bad.

Posted by Rick Long (Member # 213) on 02-04-2004, 09:32 PM:

I agree with Paul. If there was a short or ground in the line feeding the contactor, it may draw excessive current causing switch burn-out. What happens if you short 6 & 7 with a couple of aligator clips connected with, say a 5-amp fuse? (not enough to burn the automation wiring, but enough to tell if there is a problem in the contactor or associated contactor wiring).

Posted by Steve Anderson (Member # 364) on 02-04-2004, 09:55 PM:

Paul the lamphouse is a XH-XeTRON 3K Lamp house.
Also a IREM rectifier.
With the switch out I can light the lamp house, I also can motor the projector fine but no fail safes. I will try the clip and fuse method and see if I still get the short.

Posted by Paul G. Thompson (Member # 655) on 02-04-2004, 10:55 PM:

Let me think about this. In the meantime, I suggest Rick's procedure.

Something to think about - Xetron used a 240V series interlock with the power supply contactor. Something may have also gone HS with the primary wiring.

Gordon's suggestion definately has merit and might be worth looking into. There are multiple ways a technician might have used to orginally make the damn thing to work. You might have to reverse engineer that wiring to figure out what the orginal installation technician had in mind when he/she designed during the orginal installation, keeping in mind any modifications that may have been made through the years to make other things compatible with the orginal installation.

Posted by Rick Long (Member # 213) on 02-05-2004, 09:51 PM:

I beleive the wind-vane fan running detector in the lamp-house in in series with the contactor, (no fan - no go).

Something, it would seem caused a rather heavy current to burn out this micro-switch. I would go looking for faults in the contactor wiring. Perhaps a ground or a heat-expanded coil in the contactor that has expanded and is now touching a ground on its frame.

B.T.W. Is this a single booth or is there an identical system you can use for voltage and resistance comparisons?

I should think replacing that switch would be a high priority.

Posted by Steve Anderson (Member # 364) on 02-06-2004, 09:16 AM:

Well after some reverse engineering and using the test clip and fuse approach I have successfully brought this automation back to life. It looks like the switch just shorted out and caused all of the problems. I would like to replace both switches. I like the way these switches are riveted onto the panel. You would not believe the s--- wiring job in this box, I spent half my time fixing wiring splices and even found some connections just twisted wires left bare! Next time I will bring my digital camera and show you the snake nest of wiring in this system. Thanks to the Film-Tech I downloaded the manual and schematics, which was a big help. Also many thanks to you guys for the response to my question.

Posted by Ken Layton (Member # 133) on 02-06-2004, 10:27 AM:

As shipped from the factory the inside of that Co-Operator should be neat and clean without a bunch of splices/bare wires. Sounds like it must have been hacked up at one time. Jack Ondracek still uses these automations at the Rodeo 3 drive-in and they are running great. I love them.

Posted by Steve Anderson (Member # 364) on 02-06-2004, 12:20 PM:

Your right Ken, from what I saw of the unit itself the original wiring is still dressed and very nice. The additional wiring that has been added is so messed up. I will try to take a pic of this soon. BTW if anyone has any of these units not in use or has been replaced I would like to know. I would like to have some spare parts on hand for next time.

Posted by Paul G. Thompson (Member # 655) on 02-07-2004, 12:52 AM:

Good job, Steve. [Smile]