Sounds to me like the trigger transformer or associated parts are failing.
The tube will wear out eventually but it should be slow and failing bulk ca=
ps should give you flashes at lower light output before they completely fai=
l, plus they wouldn't come back from the dead.
Recharge time might be an issue if the caps can't get charged between shots=
, but that should give you pretty consistent misses at given positions but =
good shots at other positions, based on the time available to recharge.
Recharge time could be pretty minimal on a line powered system though, as o=
pposed to seconds on a common camera strobe.


-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of=
 Sean Breheny
Sent: Wednesday, January 24, 2018 12:16 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Xenon flash bulb system missing strobes

Hi Darron,

If I recall correctly, these systems work by having a medium voltage supply=
 connected across the bulb and then EITHER a separate trigger electrode OR =
a some kind of coupling (like a transformer) in series with the medium volt=
age supply to be able to introduce a firing pulse. My guess would be that t=
his trigger pulse is not happening or is not being coupled properly.
Does the bulb have two or three terminals?

Sean


On Wed, Jan 24, 2018 at 1:56 PM, Darron Black <darron@griffin.net> wrote:

> I've got a xenon flash system providing the light for a flying image=20
> capture of components on a pick and place machine.  Here's the=20
> datasheet
> (MVS-7020-04) http://www.visionlighttech.com/sap/datasheets/302-7020-
> 10.pdf
>
> Lately, it's taken to missing strobes.  The pick and place was not=20
> designed to handle missed strobes, and when that happens it throws=20
> away ALL the parts on the head at the time.
>
> I figured it was the bulb at first, and a brand new bulb appeared to=20
> help for a bit... but it's back to failing again.  I've replaced the=20
> bulb a second time with very little improvement.
>
> Since the xenon flash system is about ~16 years old... I figure some=20
> capacitors may need replacing.
>
>
> So far, I've really only got as far as the big capacitor attached to=20
> the bulb itself.  It's 12uF +/- 10% nominal, and two different meter=20
> readings put it at 13.4 and 13.6 uF.  It's of this type:
> https://chicagocondenser.com/cmp/
>
> It uses "polyester resin film and the finest grade Kraft paper=20
> impregnated with mineral oil" (or silicone dielectric fluid, it's not=20
> clear which)
>
> Can this capacitor actually GAIN capacitance as it ages?
>
>
> I don't really see a safe way to measure this system while active to=20
> see what's going on.  It's pretty high voltage, and then there's the=20
> blinding levels of light output.  It's got a door interlock to make=20
> sure you don't do something stupid like try to run it open... so I haven'=
t.
>
>
> Any other suggestions?   Does anyone else know of another common failure
> mode for flash systems?  The system is difficult to disassemble (or=20
> reassemble, rather), so I'm starting with this cap.
>
>
> Darron
>
> darron@griffin.net
>
>
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