DIY Vivitar trigger voltage modification

I was asked to mod the trigger voltage on an old vivitar 273 flashgun by my father in law. Trigger voltage was 327v. After mod it is now 5.24v. As this worked perfectly I will now mod my own 283 & 285. There is a little more room inside 283 & 285.

The diagram

What a nice modification.

It is nice to resurrect old gear for use with current gear.

Enjoy! Lon

Wow, I am definitely going to try that on my 283. Those parts are acquirable at Mouser or Digi-Key, right? I'm going the battery and LED listed are the ones built into the flash.

Also, make sure you pull out those batteries next time you pop open that flash. Wouldn't be fun to slip up and catch a shock from that capacitor... pretty lethal

I'll regard that as a disclaimer to anyone who wants to try this: If you don't know what you're doing, don't try it with a flash, it's too dangerous.

SolidxSnake wrote in post #4434907
Wow, I am definitely going to try that on my 283. Those parts are acquirable at Mouser or Digi-Key, right? I'm going the battery and LED listed are the ones built into the flash.

Also, make sure you pull out those batteries next time you pop open that flash. Wouldn't be fun to slip up and catch a shock from that capacitor... pretty lethal

I'll regard that as a disclaimer to anyone who wants to try this: If you don't know what you're doing, don't try it with a flash, it's too dangerous.

Parts are current & readily available in UK at any electronics outlet. Power is taken from internal batteries. LED is not required so I didn't fit it due to lack of space, this is simply to provide indication of trigger & reduce trigger voltage further.

I had batteries in to test unit before I closed it (only 3 fitted in that image ) but I do mirror your comments on only trying this if you are competent.

That said, make sure to discharge the capacitor correctly. I just popped my 283 open... I was a bit skeptic so I shorted the capacitor with a small screwdriver. Scared the hell out of me when I got the loud pop of the arc across the terminals! LOL

For reference, use a high-wattage resistor (I'd say a 1Mohm 5-10W resistor should suffice) and connect that across the capacitor's terminals and then measure with a DMM until the cap is discharged.

Question - some of your part numbers are different than the ones in the schematic, or the Zimmerman Schematics - http://repairfaq.cis.u​penn.edu/Misc/strbfaq.​htm#strboaof

Are there any reasons why, or any considerations for it?

You should market this!

adrenalnjunky wrote in post #4536574
Question - some of your part numbers are different than the ones in the schematic, or the Zimmerman Schematics - http://repairfaq.cis.u​penn.edu/Misc/strbfaq.​htm#strboaof

Are there any reasons why, or any considerations for it?

Parts I used are different due to availability off the shelf at my local electronics store. Optotriac is used to completely isolate camera contacts from trigger voltage. Just a personal preference.

Ok- I just pulled out my old minolta 35mm gear - One Vivitar 273, reading 223V at the shoe ready to go under the knife. Just have to find the parts - seeing as the Radio Shack part numbers in the schematis don't appear to be valid Radio Shack part numbers anymore. Of course Radio Shack isn't the same type of store anymore either. I have a local specialty electronics place I'll hit up.

wow - ok I disassembled and reassembled the flash, just as a test run. Where did you manage to squeeze those electronics?? Lord there's no room there.

Can someone explain the Thyrister specs? Mechanically I'm good, but I'm no electrical engineer. I understand the optical isolation function of the Optotriac. The Tic106D appears to be a 400v, 3.2A thyristor, where the schematics call for a 6A - is this something that needs to be varied based on the normal voltage, or will I be fine with either, just depending on what my electronics store has available?

adrenalnjunky wrote in post #4538795
wow - ok I disassembled and reassembled the flash, just as a test run. Where did you manage to squeeze those electronics?? Lord there's no room there.

Can someone explain the Thyrister specs? Mechanically I'm good, but I'm no electrical engineer. I understand the optical isolation function of the Optotriac. The Tic106D appears to be a 400v, 3.2A thyristor, where the schematics call for a 6A - is this something that needs to be varied based on the normal voltage, or will I be fine with either, just depending on what my electronics store has available?

They do fit in honest!!. I fitted 1 resistor inside hotshoe, all components were insulated with heat shrink sleeve (don't overheat it just enough to hold in place) & just squashed into wherever they would fit. I have also fitted a 100ma smd fuse into hotshoe since I posted this just to further protect camera.

TIC106D works fine & is rated at 5A, don't get hung up on the higher rated device unless you are fitting it in really old equipment. Current draw is less than 1A (measured with scope). The part number for Triac in diagram is TIC216D.

I have 2 - 283's & 1 - 285 to mod & will post when I have completed. I hope to take more images as I do these mods & post a more detailed account.

Good luck

Thanks for the reply. I went to my electronics store @ lunch and took the schematics to see what he could come up with. My father has a background with electrical engineering, mostly working with telephone switching systems for Lucent Technologies - a lot of it has trickled down to me over the years, although I have no proper schooling in the field. I'm going to get him to look everything over as well. My parts store couldn't match everything, but says he gave me either comparable parts, or ones that are rated even higher than this circuit needs. He was running off of the schematic above, so he was comparing to the Opto 3010.

For the Optotriac he sourced me a NTE3047 - http://www.nteinc.com …000to3099/pdf/n​te3047.pdf

for the SCR I was given a NTE5466 -
http://www.ortodoxism.​ro/datasheets/nte/NTE5​463.pdf

My shoe voltage was 223v when measured yesterday, am I good with these parts?

I think you are good to go. Please post back with results

Wait for the BANG!!!!!!!!!

rhys wrote in post #4542847
Wait for the BANG!!!!!!!!!

Oh s**t yea I forgot the disclaimer..........