ben plattes 6:22am, 9 October 2007
Jonathankauphotography inspired this mod. I was really craving more creative options, including wanting to use my strobes with less recycle time, a reduced need for diffusion material, and also large aperture work (like this one…
tailwhip to dusk

…where large aperture was necessary for a cool background. I decided to mod my flashes with the addition of 1) a new rocker switch, 2) a ready light on the front—so I can be cool like people who use expensive flashes with lots of wizbangs (actually I just wanted one for practical use), and 3) a sweet, sweet dial with full manual power in 12 full stops from 1/1 to ?, with ? being discussed in greater detail later. For the final results, scroll down to the bottom.

This is intended as a somewhat in-depth photo tutorial, so my directions will largely depend on the photographs, however poorly done. I didn’t really feel like burning a hole in my umbrella, softbox, or macro studio, so the lighting isn’t worthy of Strobist, but hopefully it will serve well. Also, I wasn’t using a macro lens, so overall the photo quality is subpar. Sorry. Feel free to ask questions, and this will be constantly updated, but let’s dive right in!

Disclaimer: This stuff can be dangerous. Do yourself a favor and get help if you don’t know what you’re doing, because otherwise you can end up burning, poisoning, or electrocuting yourself in any number of fun ways. I can’t be held responsible for anything you manage to break, including yourself, whilst following these insipid instructions…


Pimp My Vivitar
This is my second time through the mod, the first time was a lot of experimentation, the second was super, super easy, done in less than half the time. The loading time for all the photos may be long, please be patient.

You’re going to need:

Soldering equipment: a low wattage iron, fine guage (.032”) solder, and flux (if you’re not using cored solder, which is the cat’s pajamas).
Heat shrink tubing is quite nice and cheap, or electrical tape
Round rocker switch, I used one by Cherry Electrical.
A rotary switch, with desired number of positions (I used a 12).
Resistors, the values for which are discussed later in this post (the section with the cheesy title).
A knob for the switch.
Wire (stranded, not solid, and small guage: 20-22 is best).
An LED. I used one with a threaded mount from Radioshack.
Tools like wire strippers/cutters/crimper, a knife, something to make holes with, screwdrivers, and other things. This is not an exhaustive list.

I purchased some items online from Allied Electronics, ( and from my local Radioshack. I’ll bet you could find most of this stuff there, without having to even order online. Who knows?

Opened Case:
Vivitar 285 Flash Mod
First, open the thing up. It is a good idea to dump as much power from the flash as possible, to minimize the shock should you get careless before you have the chance to drain it manually. A full dump from the flash, then quickly turning off the unit works decently.

There are several screws that hold the lower case together, which is the first part we will work on. From the front, there are two on the left pivot, one on the right, and two on the hot shoe (the shoe must be removed before the pieces will separate. Also, the right side has a shiny metal piece just asking to be bent. Do this at once: there is glue and a metal clip that will frustrate you for a long time if you don’t figure this out. Don’t lose the opaque white plastic oval from behind the metal, it is the detent that clicks the flash through the bounce head positions.

Also, the upper portion of the flash is conveniently connected with a removable connector—not just soldered in. Take advantage of this and disconnect the flash head from the body, it will make your work simpler and lessen your chances of melting or breaking something.

As you can see in the above photo, I have severed all the wires leading to the vari power module. The Phantom is singing “past the point of no return” in your ear, but cut them anyway. A rocker switch is cooler anyway. Completely remove the module with the two screws, then install the rocker switch, which needs only a slight widening with an x-acto knife to fit perfectly. Make sure that the switch doesn’t scrape off any circuit board components when the case is reclosed.

Next, use the hole drilling device to install the LED wherever you want, but make sure it will fit when the case is re-closed. The spot that I chose has worked fine. This is what it looks like:

Front Panel:

Vivitar 285 Flash Mod

Next, the Back Panel, Guts, and a PCB

Vivitar 285 Flash Mod
Next, you have to deactivate the internal switch on the PCB. In my first attempt to remove the power switch, I simply ripped it off the board with brute force. My second try was more satisfying, I simply removed the metal contacts from inside the switch’s metal cover and replaced everything. The switch is still there and moves like it should, but has no effect. Great fun!

Next, I soldered in the new switch, but to do that, I had to make room for the wires…

Hot Shoe Hotwire:

Vivitar 285 Flash Mod

As you can see above, I clearly have violated the hot shoe. There used to be a green and a white wire running to the vari power module, and now there is none! What? The fact of the matter is, the wires simply enter the module and are soldered together. That’s it. I took the liberty of doing that with less than an inch of wire, instead of eight or nine. It’s not a pretty job, but it works fine.

Switch Switcharoo.

Vivitar 285 Flash Mod

Vivitar 285 Flash Mod

Now we can complete the new power switch installation. The hole where the green and white wires formerly resided is now the place to rout the new power switch. I soldered in a new lead from the bottom of the PCB, as seen in the bottom photo, and routed it up through the hole provided. This goes to one terminal of the rocker switch, doesn’t matter which one.

Just below the “285HV” written on the board is where the blue wire to the battery is soldered. I desoldered and removed this wire, instead deciding to save some wiring space by going straight from the battery to the switch and bypassing the PCB and the built in switch for that first stage of the circuit

The next picture shows this well:

Where the Juice Comes From:

Vivitar 285 Flash Mod

You can see here, the current path goes from the battery, directly to the new switch, and then into the place on the PCB where the old switch delivered current to. The pink wire to the battery compartment is left alone.

LED Paint:

Vivitar 285 Flash Mod

Here’s how to install that sweet, sweet LED ready light. I decided to solder in two separate wires, then splice them together with the LED leads once the flash was completely finished. This is a tight job, so be sure to have a clean, low wattage iron with a small tip. Also, make sure to tin the wires properly—they solder much quicker (stranded wire tins beautifully). If you don’t know how, there are tutorials out there on the ‘net.

The LED housing is black plastic, and sits in the PCB by friction. There is a blue wire that is the positive lead, which connects to both LED’s the red and the green. The green LED is the one we want to solder to, as that is the one that signifies the unit is charged and ready. The first wire, which I left red to remind me what lead of the LED it would be later spliced to, was soldered to the junction on the blue wire. The other wire, which I temporarily marked with electrical tape (I only had one color of wire), was soldered to the green wire, where it spliced to the negative terminal. Slide the insulating tubes back over to prevent shorting, and reinstall the plastic housing. LED is pretty much ready to go!

We Interrupt this Program to bring you a Short Message From *Our Benefactors*!

Vivitar 285 Flash Mod
*(sorry, half life episode 2 comes out tomorrow, and I can’t wait…)

This is the complete lower PCB assembly. The quick connect terminal routes down to the former switch, and the two short LED leads are prepped and ready for splicing.

Taped Switch:

Vivitar 285 Flash Mod

The other PCB is largely untouched, but I chose to make one modification before I put everything back together. There is a switch I chose to deactivate. The switch is the slightly opaque, plastic circular one on the back panel that activates the backlight. The backlight will be toast in an hour or less, so I simply placed some electrical tape over the contacts. This lets me leave the plastic button in for a more professional look, yet at the same time eliminating the chance of my flash staying lit up or shorting out when it’s in my bag. Like I said, the backlight is going to be removed for good, so the switch is useless.

Bust a Cap…

Vivitar 285 Flash Mod

Vivitar 285 Flash Mod

Next, the top portion. This comes apart with several short and long screws. Inside, there sits a Capacitorus Maximus Deadlious. Do not, repeat NOT, touch the thing until you have drained it, several times. I chose to short the contacts with a screwdriver after a full power flash shutdown, as I described before. Over the course of building my matched pair of Vivitars, I have also tried shorting a fully-charged cap, also with my mini screwdriver. The result was the sound of a .22 handgun going off, coupled with an electrical spark as big as a testicle. Needless to say, I had a natural afro for several minuetes afterwards. (I also accidentally got shocked from the thing at lower power once, but it still didn’t feel nice.)

I did three things, now that the cap is safely muzzled for the time being:
1) Label the terminals on the cap (I did R for Red and B for Black. Duh).
2) remove the transformer (that copper coil-thingy with black plastic, label those terminals as well, and splice an extended wire onto both PCB locations. You need to move this flyback transformer in order to fit the extra bulk of the switch. As you can see, I labeled the transformer with one wire silver, which connects to the side of the winding with the silver dot by it. Don’t know if the direction matters, but why not play it safe?
3) once all the stuff is taken care of, get rid of the stupid exposure calculator. Cut, unscrew, and remove all of it, including the thick plastic ring that sticks out on the outside of the body—it will get in the way of the nut on the switch. Also, get rid of the light, I cut off the white wires close to the circuit board. Also, trim the track arms on the zoom head to get rid of excess, and to ensure that the zoom head won’t hit the new switch.

Do Not Resistor You Will Be Destroyed!

Vivitar 285 Flash Mod

Now the fun part: the resistors. I chose to do a similar setup to Jonathankauphotography, with resistors in full stops from 1/1 to 1/1024th power, but I decided to use the last space on the switch for a ? position, which is a flash so low in power and so brief that I thought it might have creative applications (the less power, the shorter duration, so freezing bullets might be fun to try…) The resistors seem to follow a somewhat exponential pattern, but my choices were still somewhat fudged. The current setup works great.

I wanted to see what Vivitar used for resistor values, so upon taking apart a Vari-Power module I found what I was looking for:
Vari power OEM resistors
No resistor, open circuit: 1/1
180k: 1/2
82k: 1/4
24k: 1/16

I decided to defer to Vivitar’s resistors because, let’s face it, they designed the thing. It seemed that every stop down, the resistance was roughly halved. Here’s the final table:
Ben’s Resistor Values
No resistor, open circuit: 1/1
180k: 1/2
82k: 1/4
Approx 46k: 1/8
24k: 1/16
12k: 1/32
6.8k: 1/64
Approx 4.1k: 1/128
3k: 1/256
2k: 1/512
1k: 1/1028
Closed circuit, very low resistance: ? power…

The picture above shows the start of my soldering the resistors. Notice that I started with the small resistors, which will create lower powered flashes. There is one terminal (the first one) which is insulated and bent over. This is the full power setting on the dial. The next one, which has yet to be soldered, will be 1/2 power, and so on.

Be sure to arrange them in a way that they efficiently use the cramped space. The center terminal is the positive connection, and the resistors all are soldered together at ends opposite the switch to one master wire, to feed back to the black wire on the vertical PCB in the body. The third picture in the tutorial series, the one of the two PCB’s, clearly shows the blue and black wires that feed into and out of the resistor switch. The blue wire will end up connecting to the center terminal, as it is the positive, and the collected output of whatever resistor is selected by the switch is returned to the black wire’s spot on the PCB.

I used metal film resistors, but I got many different sizes. It made no difference, but it might be handy and easier to buy the resistors for physical size when possible.

I like to call this finished resistor assembly the Warp Drive. With a name like that, it not only looks BA, but sounds awesome too.

Installation of The Warp Drive

Vivitar 285 Flash Mod

Make sure the switch fits in the hole where you stripped out the guts of the exposure calculator. Once the is done, carefully work in the Warp Drive, making sure the solder joints stay good, and yet the capacitor still fits. I had to bend all of the contacts to ensure the cap fit, but fit it did. Next, put it all together…

Make Like a College Student and Cram!

Vivitar 285 Flash Mod

In this next photo, everything is crammed in there—the cap, the switch, and the transformer. The capacator’s contacts are safely insulated with electrical tape, after the correct wires were reattached of course. Notice that the original wire harness is routed where it is intended, and along side it runs the two wires that run two and from our new warp drive/resistor pot assembly. I wrapped the two wires in a tiny bit of electrical tape to keep the wires in order, and to protect them from the beating they take from clicking the head through all angles.

Also make sure to install all the plastic insulating sheets where they belong—there are two that go in the head—between the cap and also between the circuit board and the flash tube.

Next, the transformer plastic has been modified (to avoid interfering with the zoom head operation) and jammed in next to the cap, on the far side from the switch, and held in place with some 3M double sided tape. Test test test the operation of the zoom head now, because once it goes together, you won’t want to risk getting shocked again. Trust me. The extender wires are then soldered to the transformer, and presto, you have the finished flash head!

With the multi piece cover securely screwed back on, the only extra things appearing are the new switch, and two extra wires protruding from where the harness comes out. I used my trusty x-acto to cut a larger hole.

No Grease in My Flash!

Vivitar 285 Flash Mod

Masking tape is more slippery than electrical, so I used it to lower the friction caused by the binding of the flash head’s pivot, so I shaved the circuit board and then used two thin surfaces of masking tape to effectively “grease” the wires. You will also notice that the two wires to and from the warp drive are soldered into their places, replacing the black and blue wires.

The LED Connection

Vivitar 285 Flash Mod

Next, the LED leads are soldered to the wires coming from the original green ready light on the back. Also, the metal shoe backing plate and plastic shield are also in place in this photo.

And Then the Switch…

Vivitar 285 Flash Mod

…is plugged in. Again, it doesn’t matter which wire goes to which terminal. I recommend bending the terminals up, and perhaps trimming excess plastic from the switch in order to make sure nothing is damaged by the intrusion of space.

Now comes the tricky part. Making sure all the battery contacts are seated, the wire harness is plugged and routed, the warp drive send and return is routed safely, the battery compartment is installed correctly, all the switches are in, and all the wires and bits are safely stuffed inside is tricky. Be gentle, solder joints are strong, but why risk breaking something? Also, the wire in your vivitar may be older, or the solder joints brittle. My older HV needed quite a bit of resoldering or replacing of wires.

The second time I did this, it went together perfectly. Also, remember to replace the white plastic detent oval under the metal plate, otherwise there will be no fun clicks to hold your flash head in position.

After everything is together fine and held with the screws, it is a good time to test the flash. Run the switch through all the positions, seeing if the output is consistent. Remember, now is the time to fix it, because once you close it up and glue down the metal side piece, it will be much more pain to undo.

Below is the Warp Dial, which is similar to the one that is installed on the Starship Enterprise. However, mine is better because, as any trekkie will tell you, the Enterprise can only do warp 10.
**On a serious note, I have a PDF of the label I made in Indesign if anyone wants it.
Vivitar 285 Flash Mod

Finally, a good use for those new-fangled CD’s!

Vivitar 285 Flash Mod

Before installing the knob, I made a clear cover for the dial markings from the inside of a CD-R.

This probably wasn’t the best way, maybe eventually I will mount an actual decal on top of the CD case, but for now, it works fine.

If the flash constantly discharges from full, the selected dial position isn’t a complete circuit. If all of the dial positions are full, there is a problem with a broken connection in either the blue or black PCB wire.

If the LED doesn’t work, check polarity. ‘Member, LED’s only work one way, i.e., the red wire MUST go to the positive.

Also, if the switch is in between positions, the circuit is open and the flash will fire at full power.

Most problems can be prevented by taking your time, liberal use of heat shrink, not electrocuting yourself, and double checking the solder joints.

**Again, this tutorial will undoubtedly be revised as holes and parts I have overlooked become apparent.**

Final Results:

Vivitar 285 Flash Mod

the warp dial...

Comparison Test: Stock 285HV versus 285BDP

Original is on the left, the fully modified version is on the right. I did this to check light output, to see how my resistor values fared. Judge for yourself.




1/1, Full, Max, or whatever y’all call it.
full power

Thanks everyone! Strobist rules!

For my newest mod, the $3 VP-1 for the Vivitar 283 flash unit, check out this link!
OctopusHat 9 years ago
That looks like fun.

Thanks for the awesome walk-through.

That first pic is a show-stopper!
sar-kelandi 9 years ago
Thanks for going through all this work to share it with us!
infxualbydesign 9 years ago
replace the hot shoe with an umbrella mount and a 1/4 20 thread and i think we have the perfect strobist flash unit ( as refered t o in a thread a week or so back).. excellent i want to go and buy a vivitar just to mod it like this.......geez i am a photogeek :)
ben plattes 9 years ago
thanks for the comment!

no problem. is what strobist is all about, no?

i always like having the option of using the thing on-camera, say for a DIY ringflash or something. hotshoes aren't the sturdiest things, so I didn't really want to go around messing with mine, with the basic swivel umbrella mount/speedlite adapters are working just fine for me. in a perfect world all the photogeeks get the girls...or at least clients. drat you stock photos!
tiltaworld 9 years ago
Oh man, there goes my weekend! I just bought a 285hv for a couple bucks. It's only missing the battery holder and the vari-power knob.

I haven't read through everything yet. But if I just want to install your very useful rotary switch in the same place as the missing vari-power knob, it should be a pretty straight-forward replacement, right?

Also, you might think you didn't need that button that lights up the calculator dial, but how cool would it be if the warp-drive dial lit up? Huh? Huh?
ben plattes 9 years ago
not sure about that, see, the vari power module mounts on the front of the case, the switch sits below the surface, so you might need to build a separate housing like one designed by Ken Rappart (who's on flickr)

as for lighting the dial, that would be sweet, but quite a bit of a tight fit. i think it would be nice to just use a low power LED and let it run whenever the flash was on, who knows?

i have a few spare vari power modules, so if you need one...let me know
Scrappy P 9 years ago
This is awesome, but way over my head! I'd be sure to destroy my 580EX trying to do this!
ben plattes 9 years ago
Yeah, well the point of this tutorial is to basically make a manual, 100 dollar version of a 580. If you've got one of those, no need to! (Although if you wanted to trade...)
wcap07 9 years ago
I'm sure I'll never find the time or electrical know-how to do this, but it was fun seeing the guts of a 285!
James Kaarremaa 9 years ago
Nice...I'm glad people post technical tutorials like this. I have a Vivitar 283 that works well. I have the VP-1 module for it but in the future I might get a 285 to go with it.

The strobist group should almost be split into two groups with SO much going on in it. It seems there should be an equipment section and a technique section. Too bad Flickr groups can't be split like this.
ben plattes 9 years ago
I just got through making my own VP-1 modules for my three 283's. Note to any prospective modders: it's very simple, just go to radioshack and get a 100k pot, the audio taper is actually preferrable to the linear. They work nice!
flighthouse 9 years ago
YUMMY! This is excellent thanks a lot :)
Awe. Some!

Particularly since you went ahead and did a proper image-filled tutorial, which mine is sorely lacking in.

I laughed aloud at your, uh, terminology for the label. That is a slick job, and I applauded your use of a CD!
ben plattes 9 years ago
If there is any interest, I can also post simple instructions for making a 3 dollar VP-1 mod for the 285.
cunninghamster1954 9 years ago
I'd definitely be interested in the $3 VP-1 mod!!

Does this mod use the existing vari-power module, or is it a separate module that replaces the existing vari-power sensor and plugs into the same socket?
ben plattes 9 years ago
neither, but its quite simple.

you remove the existing module, and the mounting port with four wires. Out of those four wires, there are two that don't matter, and two that do. The two that do are usually red and black, or red and blue, the colors are dependant on the age of your model.

The 3 dollar (approx) cost is to go to radioshack or equvalent and buy a 100k potentiometer. You can get either linear or audio taper, it just refers to the curve of the graph x,y (degrees of rotation, percentage of resistance). All you do is solder the red wire to one of the three terminals on the pot, and the black wire to BOTH of the other two terminals. I used a plastic film 35mm canister base to make a housing for the pot. (hint: smaller is better, sometimes you can find a pot small enough to fit almost flush with the face).

When i'm back home tonight or later, i will post some pictures of the finished one (i did three) and also answer questions...


ben plattes 9 years ago
$3 Vivitar VP-1 mod for a 283 flash!
CotswoldPhoto Posted 9 years ago. Edited by CotswoldPhoto (member) 9 years ago

I realise this is some months since you did all this, but I have a daft question.

I am going to assume you used something like this spec resistors:

Metal Film Resistor 0.25Watt 1% Size: L6.8 Dia.2.5mm

Would I be right in that? They are the most available, I think. Maybe you could let us know what spec resistors you used.

Why did you mount a separate resistor for each terminal? Why not simply mount them in series, like this:

285HV_mod_rotary_switch_resistors (by ClevaTreva)

This would then not have the clump of wires, and the largest resistor would be half the size of yours. Maybe there isn't enough room between the body of the switch and the casing. Even so, you could have still put them in series in the harness.

Tell me I'm being stupid. Or something. Oh, and the values chosen were closer to the dividing by 2 series.

rudy__ 9 years ago
Why did you mount a separate resistor for each terminal? Why not simply mount them in series, like this:

That's what I ended up doing. I didn't record the resistor values. I only had a 10 position switch so I didn't go as low.
ben plattes 9 years ago
sorry, it's been some time since i've been to this thread.

you can't mount resistors in series without changing the values of the resistance. if i'm understanding this correctly, y'all are wondering why I didn't just go in series. I guess the answer is that is the way i decided to do it, I don't know if it works the other way or not--it very well might. you are correct though in your question of space--there isn't a whole lot of room around that big switch for resistors. the "clump of wires" actually fit pretty well, and that was using somewhat larger guage stranded wire (because that's all I had, because I was lazy, because I was poor, and because it seemed to work ok without smaller stuff.)

oh and another thing--series may save space, but what about redundancy? if you have asolder joint or resistor go bad, you lose everything "above" that resistor as well if the current has to go through all of them, there's a lot more points for failure. no worries, you're not being a pest at all. that's the entire point of this site/forum no?

as for resistors, I can't remember the specs. I basically bought them all at (worked out sweet for me) and just used the cheapest ones possible. I wouldn't nitpick on tolerance too much though, after all, these are only cheap speedlites, not missiles or cheney's pacemaker...

best of luck to you whatever way you attempt. let me know how it goes! (nice diagram by the way...)
rollabldr PRO 9 years ago
I just bought a Vivitar sensor extension cable (ebay $10), added a 100K potentiometer ($3 + knob) to the appropriate pins at the end of the cable and plugged it into the strobe. Another advantage is that I can adjust the output from the dangling cable while the strobe is up high on the light stand. I never really measured or calibrated to see if it actually goes to 1/128 but it works great and THERE IS NO NEED TO OPEN THE FLASH BODY.
tim-johnson 9 years ago
umm...i wil stick to my coloring books and legos.
CotswoldPhoto 9 years ago
Ben, thanks for the reply. I figured that space was an issue I shall have to look and see when I get inside! Also, you talk about if the selector is between terminals. Most rotary switches are make before break. I do agree with your concern over resistors going North and breaking a series circuit. The values I have chosen add up to the desired values.

I considered making a tiny circuit board, but I shall look whether there is enough room for it. The wires from the rotary switch do not need to be anywhere near as heavy duty as you have used (as you acknowledge). They need only be the same as the blue and black wires. I shall also make the connection of these two new wires coming from the head unit go via a connector, to make maintenance easier.

I shall take photo's! Fortunately, I work in a school and right next to my office is the school's electronics lab and technicians.
Steve M Smith PRO Posted 9 years ago. Edited by Steve M Smith (member) 9 years ago
Excellent work and a very clear description of the modification process.

I may try something similar. I was thinking about keeping the Vari-Power in place but modifying it so that all the auto colours still work but when in full power mode, the new power switch takes over control. (I would ignore the 1/2, 1/4 and 1/16 positions).

I think I have some rotary switches here at work which are quite a bit smaller than the standard type you have used which may make it easier to fit. If I remember correctly, it is the wafer type which you assemble yourself to whatever configuration you need. In this case, a single wafer is enough.
swandogger22 9 years ago
(Since I'm a donkey's rear end when it comes to these things I'll just make jokes.)

I'm pretty sure the department of home security is looking into this since everything above looks very technical and might be related to terrorist winning the battle of light output.
-Cue English rocker accent- This one goes down to 11....... or 12, as it turns out.
Chilin.Tran 8 years ago
in the midst of doing this mod.... radio shack only carries the a 6 step rotary switch. does anyone know where i can find a 10/12 step rotary switch? also, the different resistors, does anyone know where i can by an assorted pack of these or do i have to buy sets of 4-5 of them each at .99 a pop?

lastly, if anyone has done this mod or has these parts, i'd love to buy them off of you. please email me at thanks for the help!
ben plattes 8 years ago
Sorry, it's been a long time since I've been here. is my vendor of choice, simply because they have loads of stuff. for desposable stuff like solder and wire, radioshack works great for me.
Gonzalo, el de las fotos Posted 8 years ago. Edited by Gonzalo, el de las fotos (member) 8 years ago
Hi.. i need some help :S
the PCB has some transistors (i think) that read: "603 05G". Do you guys know what are these things?

I blew one of those when resoldering the shoe (touched 2 contacts with screwdriver), and i need a replacement. The flash charges and starts recycling, but the leds stay off and i can't fire the thing...

I figured out. I have now the Service Manual for the 285. You can ask for it...
ivar.schiager PRO 8 years ago
285 or 285HV?
How many pages?
Do you scan?
whoisjoe 8 years ago
The exposure calculator can be removed relatively easily. Inside, it's held on by a c-shaped clip, which you can pry off.
nlp239 8 years ago

Same question as Ivar - the 285 Zoom or the 285HV?
Were did you get the manual?
Onga Bonga Posted 8 years ago. Edited by Onga Bonga (member) 8 years ago
Was about to get a VP-1 for my Vivitar 283, until I stumbled over this post and the 3$ VP-1 post.
While the 3$ VP-1 is basically a sure thing to do, I got one question.
Do the resistor values above also apply to the Vivitar 283?
nathanrhoades PRO 8 years ago
Can I do this mod to my Sunpak 433? It's the canon model so it has no variable power capability now.
rudy__ 8 years ago
If it has an Auto mode then it probably can.
Winnito 8 years ago
Just one ?
Ive got 100k pot, but when I got flash apart I realized I don't know where to put the I just cut the + wire coming to the cap and that is how you regulate how much of cap is being filled, or do I put it from the cap towards the flash lamp, and then regulate how much goes out, or do I put it parallel with the cap a bit confused with that...
tnx everyone

rudy__ Posted 8 years ago. Edited by rudy__ (member) 8 years ago
No! Stay away from the capacitor.

What you want to do is to replace the sensor on the front of the flash. The sensor will have two wires on it. What flash do you have? Can you post a picture of the internal and external view?
Winnito 8 years ago
It's a sunpak 433AF full auto ttl flash, so I don't think it has a sensor on front, i did open in, but it only has two small AF assist lamps

...I thought Benjamin did that to his vivitar...switch with different resistors, all connected to main cap...
rudy__ Posted 8 years ago. Edited by rudy__ (member) 8 years ago
No. What the resistors do is make it look like a certain amount of light is hitting the auto sensor. Different resistors will make it look like more (or less) light has been reflected from the scene. The shut off electronics activates after a specific level. The circuitry then causes the current from the capacitor to be interrupted.

None of the modification touches the main capacitor.

If your flash does not an on unit auto sensor, but instead makes use of the in camera TTL circuit, then in order to get power control for the flash you will need to do something like I did with my Sunpak 355AF.

It is a lot more work.
Winnito 8 years ago
ok, tnx for the link, I'll be asking you a lot "at your place"...
outsider787 Posted 7 years ago. Edited by outsider787 (member) 7 years ago
Just to let you guys know, I've started another mod project of the Vivitar 285HV strobe.
Want to thank Ben for the inspiration, and the work he has done already to make my life a little easier.

When I get this project done, I plan on making these boards available to anyone that wants one (for a few bucks).
ben plattes 7 years ago
@outsider: that looks friggin awesome! nice work!

@non vivitar people: this mod can be done to any flash with an "auto" setting, or stepped manual. the trick is to measure the resistance of the photoresistor (or whatever is controlling the "auto") and then replace said sensor with a stepped series of resistors (not a linear relationship though, remember). a full stop is actually a halving or doubling of power, this will be reflected in the resistors.

also, don't be inserting ANYTHING between the cap and pcb. flash output power is something that you don't control with resistance like that (otherwise why the pcb?) in other words, if you don't know what a quench circuit is, or why there are three wires to the tube instead of two, don't meddle with the tube! warning!

its cool this thread is still going--I'm glad. I had no idea when i wrote this (as a freshman in college) i would be still a December graduate. thanks all!
ben plattes 7 years ago
and by the way, the flashes all still work amazing! no problems whatsoever.

however, if I could go back, i would have changed the increments, do half stops perhaps? third stops? i rarely use them below 1/32, or very, very occasionally 1/64...
SteveSnaps 7 years ago
This is a great thread, it inspired me to get some Vivitars off ebay and wave my soldering iron at them.
I won two 283s and a 285. so far only one of the 283s has arrived, but I've already had it in bits.
It came with the 1m cable to take the thyristor off the front, which I'm going to use to take all my mods to a remote box. That way the 283 can be high in a softbox and I'll still be able to adjust it. (Plus there really isn't much room inside it is there!).

Eventually I'll make use of the fire and quench with a microprocessor and have it completely wireless remote control.

I might even bare bulb it for softbox use, although that would restrict its use for other things... I'll wait to see the condition of the other two flashes when they arrive before I pick my victim.

Oh yes, one last thing, I metered the hotshoe... 300v... I think I'd better remove the shoe mount before anyone puts it near a camera hotshoe!
ndrajyaguru2 6 years ago
I have vivitar 285 flash my problem is when i start flash ON fash work properly but 2nd fire fash take time to charging and sound continuslly coming so what the technical problem i can solve my self
Benjamin Cahill 6 years ago
Have you got fresh batteries in it? What does the red/green light show?
Eugeniu 6 years ago
is the Vari Power extention cord the same for 285 and 283 ?
Peter Mars Photo 5 years ago
alohadave 5 years ago
Bumping 1 very old thread was enough. You did not need to bump this one as well.
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