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chirantha7777 Oct 10, 2010 9:37 PM

Fixing Vivitar SF-4000
Ok, so I bought a Vivitar SF-4000 from Ebay which stopped working after 3 days...

Two days ago, since I am good with tools I decided to try and figure out why it was not working. I inserted for the first time four Alkaline batteries instead of the NiHM 2450mHA I've been using. Viola! it worked... the dead SF-4000 sprung back to life.... but here the next problem....

Alkaline batteries didn't last for more than 120 shots... and the flash started to miss... which is a weird behavior. But when I installed NiHM batteries it still doesn't work at all.

App-on investigation I found that some devices don't work well with NiHM batteries because they are 1.2V instead of 1.5V (standard). Well duh.... I found the problem... VOLTAGE... 4.8V is not going to be enough for a 6.0V flash!

I ran in to stone wall... Alkaline batteries are expensive and as a person that takes 400 photo's a week, it was not helping at ALL! Then I noticed 4.8 + 1.2 = 6V!!! Eureka! So I opened up the Vivitar flash made a hole and managed to install a external battery holder connecting one more rechargeable NiHM in series... Guess what! now I gots 6V and all the batteries are recharable...

Ok first day outside I found a big problem. The slave sensor needs to pickup bounced light! So if you shooting the sky the flash isn't going to go off! So what I did was I removed the front "Vivitar" cover (its basically glued to it) and looked at the sensor... to find that it is a bit too inside for the flash from the side reach it.

I removed the flash once more and removed the circuit board... and got a nasty shook as well. :( so I remove the glued slave sensor and used a drill to widen the hole so much that it allowed me to take out the sensor!

So I fixed everything back together and pointed the sensor to the side... and glued it using double side tape.

DONE! I hope it works for at least 12 months :)

dr_spock Oct 12, 2010 10:30 PM

Cool. Do you have photos of your modifications?

VTphotog Oct 12, 2010 11:02 PM

I have had a problem with a light sensor on a different piece of gear, and got it to work better by glueing a small, convex lens in front of the sensor, without disassembling the unit. Beats getting electrocuted.


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