Paul C. Buff, Inc. Technical Forum

Hello all, I have a White Lightning Ultra1200 and Ultra1800 that I've been using for about a year now. The more trustworthy one is the 1200 for my shoots as it's fired every time I hit the trigger. At an event requiring strobes 2 weeks ago, as always, I plugged it in and test fired and also dumped the charge. Both times it would fire, but then one half of the flash tube would stay dimly lit and after a minute's wait, the fuse would pop. It does this with or without remotes/triggers attached and at all power levels.

Any ideas/fixes? I'm in need of lights, and my AB800's won't be here for a few more days.

Thanks!!

This means an SCR is not +shutting of the supply of power to the tubes. This can indicate a faulty SCR, or low voltage coming from the power supply (which can be compounded when using two lights on one circuit).

Does the same light do this when it is the only light firing? Does it do this on a different circuit/location?

If push comes to shove, and because they are ULTRA's, if only one tube is doing this, you can remove the tube, and use the light with the remaining tube. Your light will have only half the power, and there may be some pattern issues with direct focused reflectors (including PLM), but it will still fire.

If you do this, be sure to unplug the light. Since both tubes are firing, you can safely remove the tubes after a couple of minute (to be super safe). If one tube did not fire, you would want to wait much longer. Be sure to use a clean glove or tissue to remove the tube to prevent damage for future use.

I've only had these lights for about a year now, and have worked relatively flawlessly until last weekend. I haven't used them for studio work, but rather large venues to shoot roller derby, and off and on, I'll have them on a different outlet (always one per circuit), but typically the same ones each time. When the 1200 started this, it was on the same circuit it's been on at least a dozen times before. Each light is about 100 feet away on different circuits, and I also tried it on my kitchen outlets as well with the same result, so I seriously doubt it's that.

When it's happened, each time it's the opposite side of the tube that stays lit. I'll turn it off, reset the fuse, turn it on and try again only to have the other side stay lit after. I have a few spare tubes, so I can certainly try replacing that. If it's the SCR, that will be more tricky. I do have a few AB800's showing up in a day or two, but was hoping to inexpensively repair this to be able to create more light. We'll see how the tube exchange works...

Thank you!

It will not be a tube problem, it is an SCR problem, and it sounds like it will need to come in for repair, based on your description. For clarification, it is an SCR (internal part) problem, not a CSR (CyberSync Receiver) problem.

This is called "afterglow", where the charging current keeps the tube conducting because it never stops being ionized.

All our lights have circuitry to make sure the tube has stopped conducting before charging current is applied.

Sounds to me like the "afterglow protection" circuit has failed in your Ultra, and will require repair.