Film-Tech Forum ARCHIVE: ORC1000 lamphouse flashing?!?!

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Posted by Dan Lyons (Member # 1454) on 01-25-2003, 03:00 PM:

Question for the experts.

I've come across an ORC1000 lamphouse for sale. In talking to the seller about condition, he tells me the lamp doesn't stay contiually lit, but flashes like a strobe light, and increases and decreases in flashing speed when the voltage dial on back is turned.

Is this just a case of a bad lamp, or are the innards of this screwed up? [Confused]

Expensive to fix? Not sure if I should go for it or pass on this one.

Thanks
Danny

Posted by Paul G. Thompson (Member # 655) on 01-25-2003, 03:24 PM:

That flashing you see is the ignition attempts of the bulb. If the bulb is bad, it probably won't light. But don't allow that igniter to continue attempts like that. That can damage the igniter.

However, if the bulb is OK, then there is a problem with the lamp. If you can, disable the igniter and measure the open circuit voltage.

The most common failures I have seen with those lamps are SCR Boards, Regulator boards, and the blocking diode.

Posted by Mark Gulbrandsen (Member # 72) on 01-25-2003, 11:50 PM:

Dan,
Don't know what you are going to pay for it but it definately needs work!! Take that into account in your dealings for the thing.
I don't know how versed in electronics you are. But if this is happenning only with the bulb lit then it may be a bad diode in the bridge rectifier. These lamphouses developed a bad reputation years back, and for no real reason too...They are actually quite good, and amazing for the time period they were designed in.
The best thing to do with a 1000 is to completely rebuild it. Replace all the diodes in the bridge, and the blocking diode with 85 amp devices. Rebuild the two control boards by replacing all the electrolytic capacitors on both of them first. Also if the main filters are really old replace them as well. There is a date code on those coke can filters in there thats pretty obvious if you pull one out. Capacitors generally have a rated life of 5 to 7 years of servie....and these operated in a lot of heat for years!! After this if you still have problems its time to replace all the semicionductors on both PCB's. These are all still available and total cost about 10 bucks. I'd expect the total parts overhaul to cost less than 100 dollars at your local electronics supply house, inculding the big filter caps....providing that you can do the work yourself. After overhauling and upgrading the diodes the 1000's are always 100% reliable. Also stick with using a 700 watt lamp in these units!! They were derated by ORC quite a long time ago, but the 700 watt lamp basically puts out the same amount of lumens as the 1kw lamp does.
Mark @ CLACO
www.clacoequipment.com

Posted by Steve Kraus (Member # 476) on 01-26-2003, 12:13 AM:

Yeah, definitely get 700W bulbs. The ORC 1000, despite the name (and probable intent) can't run a 1kW bulb in the proper current range. They're not very happy going too much beyond 40A. Using a 700W is a better match to what current levels you can actually generate and since it's the current that determines the light output of a given lamphouse the light will be exactly the same and you will avoid having bulbs start to flicker from arc wavering because you can't give them the current they need to be stable.

The ORC 1000 is regulated via a TRIAC or paired SCR's acting like a large light dimmer (phase angle, % of the AC waveform passed) on the incoming AC. Presumably the transformer is designed to handle the funky waveform that results. I always wondered about dispensing with the regulation and just having the current adjust pot run the TRIAC directly, given that many/most rectifiers aren't regulated anyway.