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Profoto B1 Inconsistency

  
 
leethecam
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p.1 #1 · p.1 #1 · Profoto B1 Inconsistency


Usually my B1 strobes are spot on accurate when it comes to the exposures - nailed down to a 1/10 stop accuracy with hardly any variation.

However, one of my B1s is showing variations of up to 1/3 stop at the lower powers, (pretty solid at high / full power).

I've run the whole thing through at full power many times to see if I can settle the tube, but no joy. And I've tested against my other B1 in exactly the same conditions, (blacked out room, meter immovable, radio triggered with Profoto triggers - usual things...)

The other B1 is solid, so I know it isn't my testing.

In the past I've had this and solved the issue with a replacement tube - which is annoying as otherwise they look fine. (Keep for spares I guess, but I've already go two of the old ones...)

Removed the tube, gave things a quick check / clean and replaced. Tried the old tubes (which I'd replaced years back when they did something similar) and get the same.

So currently looking to stump up a chunk load of change for a new tube.

But am I missing anything? Any other thoughts to rectify the problem apart from tube replacement. Pretty sure it is the tube and not the capacitors, as this is something I've had / fixed before.

(Heck, no point in having a very accurate flash system if it isn't accurate 🙂 ).



May 31, 2022 at 01:34 PM
story_teller
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p.1 #2 · p.1 #2 · Profoto B1 Inconsistency


The flash tube is just a resistor and shouldn't vary its resistance from shot to shot. Over time the flash tube will change its resistance value, but I would be inclined to look at the capacitor and charging circuitry.

It would be a bit of work, but you could switch tubes between the B1's and see if the problem follows the "bad" tube.



Jun 01, 2022 at 05:27 AM
Simon Barker
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p.1 #3 · p.1 #3 · Profoto B1 Inconsistency


If your other B1 is fine then you should use its tube in the head you're having issues with, that will confirm if it's the tube or head.


Jun 01, 2022 at 11:38 AM
leethecam
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p.1 #4 · p.1 #4 · Profoto B1 Inconsistency


I fitted a new tube and it solved the problem.

I was hoping for an idea that could fix things without the expense - but alas none came to mind. Hopefully this doesn't happen any quicker than the 4 year cycle I seem to have at the moment.



Jun 01, 2022 at 12:56 PM
3BIGMAMAS
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p.1 #5 · p.1 #5 · Profoto B1 Inconsistency


when I had issues of consistency with my B1x I found out the first time it was the flash tube getting old and got it changed.

The second time it was due to the battery getting old as well.
That one time it was quite easy to spot the issue: The unit ran perfectly with another battery.




Jun 04, 2022 at 10:37 AM







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