Vivitar 283 repair?

[Bill Baxter]

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.

[Fred McKenzie]

In article <n92ett$17g$1...@dont-email.me>,

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

[whit3rd]

On Friday, February 5, 2016 at 7:28:44 AM UTC-8, Bill Baxter wrote:
> I have some Vivitar 283 flashes

> After about 5 years and recently, I brought out the flashes to use...
> ... 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.

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.