Film-Tech Forum ARCHIVE: Barco 32B Arc Wander

This is topic Barco 32B Arc Wander in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Jay Glaus (Member # 6011) on 09-02-2015, 11:10 PM:

Been having a few Ushio's lately develop arc wander and/or a flicker. I run DXL-65BA's and 70BA's in my 32 depending on the time of the year and how the setting sun hits the screen. My 65BA I have in there now has developed what appears to be an arc wander at only 100 hours run time. If you put up a white test pattern you can see it from the first two rows, and you actually can notice it looking at the light in the booth. I was touching up the alignment and noticed it jumping around sporadically between .75 and 1 footlambert at a time while barely moving the bulb.

My 70BA's tend to come out looking a little better. However, they don't stay in as long as the 65's and I don't have to push them as hard to get 10-11 footlamberts on the screen. Maybe it's all relative. I have nearly 800 CFM at the projector and leave the fan on 10-15 minutes after extinguishing bulb.

But, I was curious if anyone has noticed a batch of ushios developing those symptoms lately? Maybe it's just me.

Posted by Brad Miller (Member # 2) on 09-02-2015, 11:32 PM:

This is probably your issue.

Posted by Jay Glaus (Member # 6011) on 09-03-2015, 02:06 AM:

Hey Brad,

That actually was my issue at one point in time. I kept asking barco over and over why my 32 was eating bulbs like crazy. I wasn't even getting to half life before I was well below 50% light output. And it looked like on the anode that it was burning on the edge and up onto the anode's side. Ushio was probably getting tired of reading my warranty claims.

Funny thing was I had asked Barco if they had an adjustment for magnetic stabilization on the lamp house and was told they do not use magnets to stabilize the arc in a barco lamp house. Okay... Then a few weeks later they came out with that InfoT. The magnet that didn't exist now might be backwards. Sure enough mine was backwards. We switched it and finally got to experience the blue tail light that tells you your bulb is nearing end of warranty.

Everything seemed fine for the longest time until a couple of recent bulbs. Thats why I was thinking maybe we had a sour batch out there. But, I hadn't really heard of anyone complaining so I could have just gotten lucky I guess.

Posted by Monte L Fullmer (Member # 2797) on 09-03-2015, 07:26 PM:

I did this procedure to six, 32B units to correct the abnormal short life and hard striking on the 65BA bulbs used in these units.

Used a compass to identify polarity.

-Monte