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Old Jan 14, 2003, 9:48 PM   #1
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Default Question about Vivitar 285/285HV

greetings from sunny florida,

i hope one of you vivitar experts can answer a couple of questions.

i just purchased a 285 & a 285HV used from ebay. the 285 takes the sb6 power supply. the 285HV takes the sb4. they didnt have any manuals. what is the difference between the 285 and 285hv. (i do know they take different power adapters )

how can i test if the power adapters are actually working? it appears that i must have working batteries in the flash for it to run on AC. doesnt make sense. i would think the power supply would take the place of batteries.

when i plug the sb6 power supply into the 285, the flash operates even when the on-off switch is off. is this normal??(the 285HV does not do this).

if i put a multimeter across the power supply terminals, how much voltage will i see? AC or DC?

enough babbling

thank you in advance

mikey
8)
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Old Jan 14, 2003, 11:34 PM   #2
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Quote:
they didnt have any manuals.
Mickey, here is the 285HV manual :
http://primco.org/photo/galleries/vivitar_285_manual/

Quote:
it appears that i must have working batteries in the flash for it to run on AC. doesnt make sense. i would think the power supply would take the place of batteries.
Their synchronization circuits ( the main electronics in a flash, beside the voltage step up circuits) still use low voltage power from the batteries. I agree with you that it doesnít make sense technically and logically, itís just a way to make things simpler for design folks (and cheaper of course)
Depending of each flash manufacturer design, the AC adaptor will supply high AC or DC voltage to directly charge the main high voltage capacitor (instead of step up the 6 VDC to have 600V for capacitor, for instance)
I donít know in deep the Vivitarís design, but looks like the adaptor have only that purpose, leaving the electronic still using the battery low voltage for operation.

For your information, Metz 45 series use external adapter to power everything, the main capacitor charging, AND the electronics. You donít need alkaline, nor rechargeable batteries on board to operate.
More than that , a lug on the 45-CT1 mechanically prevent you from plugging the adapter if the power switch is not at OFF position. Of course, there is a price for that, Metz have to add a voltage stepdown circuit to power the low voltage circuits from the 400 VAC of the adapter.

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if i put a multimeter across the power supply terminals, how much voltage will i see? AC or DC?
I guess itís AC (like on my Metz) , in the 200-400 volts range
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