Film-Tech Forum ARCHIVE: Upgrading from a 1.6k lamp to a 2k

This is topic Upgrading from a 1.6k lamp to a 2k in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Michael Brown (Member # 890) on 09-05-2003, 01:02 PM:

We currently have a 1600watt lamp and we will be buying a new 2000watt lamp. (the new lamphouse supports 2000watt lamps but we continued using our old lamp)

Do I need to change the output current from the rectifyer? (We have a rectifyer that has a big dial on the front that controlls the current)

Posted by Jack Ondracek (Member # 1466) on 09-05-2003, 01:25 PM:

If your rectifier is rated for a 2,000 watt lamp, if you have enough cooling for the extra wattage and if your wiring is large enough, you probably can do this. You should have enough headroom on the supply side of the rectifier for the extra wattage, but now would be a good time to confirm that.

If all is rated for the increase, then the dial on your rectifier may be all you need to bring up the current. You (or your tech) might have to change a tap in the rectifier to get the range you need, but this isn't normally a big deal.

Posted by Michael Brown (Member # 890) on 09-30-2003, 04:34 AM:

So the 1.6k runs at about 65amp. What should I run the 2k at?

Posted by Darren Briggs (Member # 1071) on 09-30-2003, 06:17 AM:

Run the 2K at 70amps nominal, but you may find 65 amps when new is ok. Then increase it to 70 after 700 hours or so.

Is the Mirror in good shape?? Ive just downgraded to a 1.6 form a 2K in one screen just by buying a new mirror.
ALso ensure the aligment of the lamphouse is perfect, you can increase light no end. If you aint got a laser etc, buy a pin hole apperture plate , this can aid alignment.

What lamphouse is it?

Darren

Posted by Steve Kraus (Member # 476) on 09-30-2003, 09:07 PM:

Yes, the rectifier setting determines how much current goes through the bulb, not the bulb itself (and completely unlike a common incandescent bulb). It's important to run the bulb within its rated current range starting lower and then increasing a bit (while staying in the range) if you are to get maximum bulb life.

At a post house I used to work at we had a number of those infamous ORC 1000 lamps with the self contained rectifier. We had been using 1000W lamps but despite the name these units couldn't do more than about 40A while a 1K bulb really ought to be run around 50A so our bulbs would start to flicker as they aged and we'd have to replace them early. It was suggested that we start using 700W bulbs instead and the bulb life went to what it should be. The average person might think a 700W bulb is going to put out less light than a 1000W bulb but that's not true when in both cases the bulb is running at 40A. Light output is exactly the same. Just the bulb is better matched to the available current.

Later I put some of those early-retired 1K bulbs in larger lamphouses with rectifiers capable of 1-2K so they could be run at the proper current and they ran fine without flicker.