ORC 1000 - Alignment Drift.

[Mark Gulbrandsen]

Josh, to try to clarify, the flickers now are sporadic. How best to describe them? almost more like random flicks, not a steady flicker. I ran a feature Saturday and there were these random flicks in the first 10 minutes or so and then rock steady for the balance of the 2 hour movie. Yes the meter did move some with these occasional 'flicks'

Dave, working on finding replacements caps for the boards. I did replace those big caps through this mess also.

Didi-Key or Mouser are my go to sources for electronic parts. But beware... Some of the semiconductors are almost impossible to find these days as are substitutes. The main stud mount rectifiers and blocking diode are still standard parts. A friend in the UK has spent months trying to find a few parts he needs for his. Also' should you replace the main rectifiers or the blocking diode, then use the next size up. I did that with 2 of mine I used on Location Dailies jobs, and those diodes will never failed again.
Also, an intermittent blocking diode will give the flickers... I have seen that happen in theaters that used them.

[Bill Duelly]

Mark, are you referring to the one on the center bulkhead as the ‘blocking’ diode?

[Mark Gulbrandsen]

Mark, are you referring to the one on the center bulkhead as the ‘blocking’ diode?

Yes, it's usually the first diode that fails in a Model 1000. I was thinking about this last night, and I am pretty sure that I installed an 85 amp diode in that spot.

[Josh Jones]

Easy enough to check. Monitor the voltage across the diode during operation (after lamp ignition, careful as the RF pulse can destroy your meter!) The voltage across the diode should be around or less than 1V with little change. If you see large fluctuations, the diode is bad.

[Mark Gulbrandsen]

Easy enough to check. Monitor the voltage across the diode during operation (after lamp ignition, careful as the RF pulse can destroy your meter!) The voltage across the diode should be around or less than 1V with little change. If you see large fluctuations, the diode is bad.

I generally connect the meter after the lamp is lit. It's low voltage a that point, but still high current that can damage things if you slip and also hit ground....

[Bill Duelly]

Mark, Today I swapped out the one from the backup unit, so will test out soon to see if that did the trick. (I dont fancy messing around with the lamp lit!) Thank you for the advice!

[Mark Gulbrandsen]

Bill, Let me know how it goes. I shotgunned the 1000's I had... Basically replaced all the high power semiconductors, and all electrolytic's. Had zero trouble with them for over 6 years. Then I switched to Super Lum-ex's, and sold the ORC's.

[Bill Duelly]

Sorry my delay in response but I wanted to be able to run an hour reel as a test vs a short 20 minute reel (I’ve done both).

there are still a few very brief flicks in the first 3 minutes or so and then rock solid after that (for both length reels). I’m still planning on replacing what I can on the control board as well as adding a new blocking diode and the small caps on each side.

i can’t say enough, thank you folks for your input and assistance as I work my way through getting this back up and going!

[Josh Jones]

Another thing to try, clean the current control pot. I could see how if it was noisy, you could see fluctuations in the output. It looks like a 5W wirewound type. I'm always amused by phase control circuits in high power applications. The Continental FM transmitters regulated output power by doing something similar, a three phase light dimmer in front of the plate supply for a 20,000 watt FM transmitter. Many of those circuits did not like running far from full power, as line fluctuations would cause large changes in output power. That's why your dining room light dimmer will often go out when your AC kicks in.

[Mark Gulbrandsen]

Sorry my delay in response but I wanted to be able to run an hour reel as a test vs a short 20 minute reel (I’ve done both).

there are still a few very brief flicks in the first 3 minutes or so and then rock solid after that (for both length reels). I’m still planning on replacing what I can on the control board as well as adding a new blocking diode and the small caps on each side.

i can’t say enough, thank you folks for your input and assistance as I work my way through getting this back up and going!

Bill, That could also be the arc wandering around a bit until the lamp warms up, especially on a high hours lamp. But IF the electrodes are in nice shape, then that is not likely the case... if you get new diodes, get the 85 amp for the blocking diode. Just compare the size to what's in there now, so you can be sure it fits. I think there is also a mica and a stem insulator on it as well.

[Bill Duelly]

Mark, if only I saw this 24 hours prior to your posting… I had found and ordered a direct replacement diode! (As well as a pair of the caps that are just before and after it!) ?. Will post a follow-up after I recap the boards and replace this diode. Long and the short so far is that the nasty flicker is gone and I’m working on investing in long term capabilities of the lamphouse! I’m not done watching movies yet!

Josh, are you referencing the control on the rear bulkhead, just below the amp meter? I presume using something like tuner spray?


Circling back to the original reason for posting… so for the testing this past week it appears that the lamp focus has been holding its position… To reiterate what was done in that regard: on the center bulkhead, a small right angle bracket, that was welded to the lower casing, had broken its weld. I fashioned a small right angle bracket and mounted it on the opposite side, result being a firmly set in place middle bulkhead! Also, the various washers, particularly the ‘cupped’ washer in the friction adjustments for the reflected assembly were askew, so I loosened the bolt, recentered and tightened them.

[Mark Gulbrandsen]

It is easy to make them extremely reliable lamp houses, just by updating the Bridge Rectifier diodes and the blocking diode to 85 amp from the original 40 amp diodes pretty much does it .Plus recap the boards and the main caps. I also had a pair of ORC 1600's I used and had done the same thing to those. They are more reliable than when they were sold new.

[Gordon McLeod]

Yes, it's usually the first diode that fails in a Model 1000. I was thinking about this last night, and I am pretty sure that I installed an 85 amp diode in that spot.

I usually put a 600v rated as well as the lower voltage ones were more prone to failure

[Bill Duelly]

Got my box of replacement capacitors from Mauser today so I’ll be working on the circuit boards for the next few days….

[Bill Duelly]

OK, one month later. I'll just say lots of 'life issues' the past 4 weeks which prevented this from following through in a timely mannor so this was spread out over stolen moments here and there. Some things I did do: Replaced as many caps on the boards that I could find replacements for. Funny how in doing that, the board I did the lease amount of work on seemed to behave the best!

Ordered and installed a replacement blocking diode using the code from the ORC manual.... wouldnt' light. Swapped it with the one from the back up unit and lit. who would have guessed?! the piece did appear new!

Still some minor flicks......

I decided to change the bulb again from the one I had been using to a newer looking one. In doing so this time, I noticed 2 things: 1) the clamp with the allen screws on both sides, even though appeared tight, all it took was a quarter turn and it slid right off. Could one of the screws not tighten all the way and was sticking, thus prevent a solid contact? I am loathe to go too crazy with this clamp since it hangs on the unsupported end of a xenon bulb! 2) also noticed that there was a little wiggle on metal end of the bulb. Took the bulb out and examined it and found that the cement(?) holding it in place was crumbling so there was that wiggle. Put other bulb in, made sure allens WERE tight and gave it a test run a 20 min reel and later an hour one. SOLID LIGHT! So I appear to be back in business.

So to summarize in brief:

Initially putting the cap back in, reversed, screwed up some electronics. Lots of caps and diodes were replaced. in testing and swapping bulbs, I also had a bulb in the mix with a loose base and apparently a clamp that wouldnt tighten 100% which could also have caused some flicker with any bulb with a loose contact, thus prolonging the repair/test process.

Oh and the light seems to be staying in position and not needing constant tweeking.....

I certainly wish to thank all you great folks here on Fim-tech in guiding me throughout the process!!!!!!!!!!