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Vivitar 283 repair?

I have some Vivitar 283 flashes I used several years back in lower power mode for a special application (I swapped out the thyristor for a circuit that allowed 1/16th power). The flashes were controlled as slaves (using Wein peanuts) from my main camera, a Canon Rebel at the time. The flashes performed flawlessly for the few weeks that I needed them and then stored away.

After about 5 years and recently, I brought out the flashes to use now with my Pentax KX for macrophotography and thought they would be ideal still at 1/16th power. They started off working ok again as slaves with the peanuts, but have quickly become erratic and I don't know why. Not just one, but all of them after just a couple of days of use. What's generally happening is that they won't trigger from the main flash. I suspected the peanuts and swap them out, but they still won't respond. I used contact cleaner on the peanuts themselves, then carefully inserted into the 283's, but this didn't help. Also, even if I push the ready light button on the 283's, they won't fire. Sometimes the ready light is flashing, sometimes steady but doesn't seem to matter.

I can hear the whine of the flashes, mostly steady but in some cases pulsing as the light flashes. Nothing matters though as any/ all of the flashes won't flash. I've swapped out batteries for others, used the DC to AC adapter for the flashes, and mostly they won't respond or very erratically.

Any ideas what's going on? I do notice that if I short the hot shoe terminals, nothing is happening on any of the flashes. I can sometimes get them to fire if I keep bending them, but not always.

Any help for these 283's or time for something else? I'd hate to lose all 3 of them, but none of them seem to want to work properly.

Reply to
Bill Baxter
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Bill-

It was my understanding that the flash is turned off when it reaches a critical brightness, determined by light reflected to a photocell. Some models react to the camera's metering system to determine when the correct amount of light reached the film. Your modification probably bypasses the automatic circuitry and stops the flash at 1/16th power.

That said, I don't see how your modification affects firing of the flash in the first place. I believe that is done by dumping a capacitor's charge into the primary of a small ferrite-core ignition transformer. The high voltage secondary of the transformer is connected to the outside surface of the glass flash tube. The voltage pulse is capacitively coupled through the glass to the Xenon gas, causing it to ionize.

The problem you describe suggests that the ignition transformer or its firing capacitor is leaking. It might be caused by bad contacts in the camera, but I think you have ruled that out.

You may be able to replace the capacitor with a commonly available part, but I don't know where you would get a replacement for the ignition transformer. Perhaps leakage was caused by absorption of moisture from the air, and could be reversed by baking at a low temperature, or using a dehumidifier.

Fred

Reply to
Fred McKenzie

It's possible that the discharge tubes have gone gassy; that would cause the breakdown voltage to rise (and make triggering hard). Some diagnostics are possible, if there's a neon sign shop in your neighborhood... or if you have a Tesla coil in your toolbox.

Reply to
whit3rd

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