Strobes/Flash Capacitors

[hjoseph7]

Why are some Strobe or Speedlight units seemingly immune to occasional maintenance, while other units have to be fired off a few times every 3 months or so ? I have some old Metz  and Norman units and if I don't fire them off every 3 months or so, the capacitors start going bad and I have to reform them. That's IF they are not too far gone. I also  have some strobe units like my Alienbees where I don't even bother to fire them off. I put them in storage and forget abou them until I have to use them. Some actually sat for 5+ years in storage and when I finally got a chance to fire them off, they performed perfectly with no problems. I still have my first ever speed light that is about as old as I am(and thats old!) That thing has been sitting in my bag for years due to sentimental reasons. A few weeks ago I took it out of the dungeon, put some new batteries in it and it fired like it di 30+ years ago ! I don't get it, why would a manufacturer want to use finicky capacitors instead of more stable ones ?    

[rodeo_joe1]

18 hours ago, hjoseph7 said:

I have some old Metz  and Norman units and if I don't fire them off every 3 months or so, the capacitors start going bad and I have to reform them.

The clue is in the word 'old'. Electrolytic capacitor technology has advanced a lot since the mid C20th and the chemical dielectric layer is thinner, stronger and more long-lasting than it used to be.

It could also have something to do with how hermetically sealed the casings are. There has to be an elastic seal to allow for temperature expansion and outgassing. Old capacitors used to have a rubber sealing cap, but I guess that's now been replaced with a better synthetic material that's less permeable to atmospheric gases. 

Anyhow, it's an age thing. 

[hjoseph7]

6 hours ago, rodeo_joe1 said:

The clue is in the word 'old'. Electrolytic capacitor technology has advanced a lot since the mid C20th and the chemical dielectric layer is thinner, stronger and more long-lasting than it used to be.

It could also have something to do with how hermetically sealed the casings are. There has to be an elastic seal to allow for temperature expansion and outgassing. Old capacitors used to have a rubber sealing cap, but I guess that's now been replaced with a better synthetic material that's less permeable to atmospheric gases. 

Anyhow, it's an age thing. 

So I'm guessing that none of the more modern units require this mandatory maintenance ? However, I owned a Metz 76 MZ-5 that I think I purchased back in 2012. That is not really that old, but it still required this 3 month maintenance. I no longer own this unit, because it blew up on me after being in storage for 5+ years and I tried to fire it off. My other much older Metz units such as the CT-4 fared a lot better.  I still have them and they work fine.  

[laurencecochrane]

Back in the day it ws common to way overengineer products SOME even designed to LAST FOREVER. This is rarely done today. HOWEVER some materials used in manufacture today are FAR SUPERIOR to what was availible back in the day. I get critisized often for useing modern components tech on on old cars / machinery.  Some folk go nuts when they see an alternator on an OLD CAR. Me ? Do what you have to do to make it work or work better.. So it can be practically used as it was intended to. NOT JUST A SHOW PIECE.

[rodeo_joe1]

20 hours ago, hjoseph7 said:

So I'm guessing that none of the more modern units require this mandatory maintenance ?

All electrolytic capacitors use the same principle of a thin dielectric film being formed on the surface of a conductive foil when a polarising voltage is applied. The formulation of the electrolyte and surface texture and alloying of the foil are proprietry processes, so the longetivity and depth of the dielectric is bound to vary between manufacturers and between quality banding (binning) of components. Plus there's always an inevitable variation introduced during production.

Another factor, IMO, is that companies like Metz seem to have been quite conservative in their circuit designs and selection of components. Maybe preferring to use home-grown suppliers, rather than more progressive imported products.

[ed_farmer]

If the flash has been stored for a long time (or if you are not certain) do NOT fire the flash.  Firing the flash actually does nothing to help restore the capacitors.  

Connect the flash to whatever power supply (insert batteries, connect to an external battery or plug it in) and leave it alone for six to ten hours a day for three or days.  After this you should be good to fire.  If the flash still fails, you didn't have a chance from the start.  

The capacitors weaken when they are fired too often OR when they sit without a charge for too long.  This process can restore those damage in either way.

[rodeo_joe1]

A pretty good guide to the state of the capacitor(s) is to see how long the flash takes after switch on, with fresh batteries or plugged in, before the ready light comes on. And how long it stays lit after the unit is switched off. (Newer units only show the ready light while powered on, so this test might not be viable.)

Anyway, a good capacitor will keep its charge, and hence the ready light lit, for a couple of minutes or more after the power is turned off. OTOH it'll flicker and extinguish after only a few seconds if the capacitor is bad or needs re-forming. 

Edited February 21, 2023 by rodeo_joe1