These flash guns have been around for ages and are built like tanks so there's loads of used flash guns available for purchase online.
Many new strobists buy a used 283 to start experimenting and are usually tempted with customising this flash gun to their needs, but struggle to take it apart.
I recently bought a used 283 for a few quid to use a slave unit but the PC sync socket was not working properly with my Wein optical trigger, so decided to take the apart flash gun to see if I could fix this.
After digging around online for recommendations, and using tips and partial instructions from various different forums, I managed to safely disassemble my 283, fix the PC sync socket and put it back together with no problems.
This instructable combines in one place the tips, instructions and recommendations I found online, in an attempt to save new strobists the hassle I went through.
DISCLAIMER: if you disassemble your Vivitar 283, you do this at your own risk!
Step 1: SAFETY FIRST! Read Before You Open the Unit
These instructions assume that you power your 283 with regular AA batteries. If you use an A/C adaptor or other external power supply, find out how you can discharge the capacitor before following any of the instructions on this instructable
Although they use regular AA batteries as main power source, flash guns work with high voltage.
Discharging capacitors with your bare fingers will be very painful and can produce significant harm so be very careful!
With a fully charged capacitor, the voltages inside the 283 can be around 200-300V DC.
The main capacitor inside a 283 (see picture on the last step of the instructable) holds a substantial charge for a long time after the unit was switched off and the batteries have been removed, so you must discharge it before you open the unit.
To do this, turn the flash on, set it to the highest power and wait for the "ready" light (test button) on the back of the unit to start flashing.
Once the light/button is flashing, switch off the unit, very quickly remove the batteries and fire the flash by pressing the test button (the one that was flashing).
This should eliminate most of the charge in the capacitor but be aware that there could be some residual charge left on it.
If you want to be 100% sure, check the voltage in the capacitor with a multimeter before you touch anything inside the flash gun.
If the capacitor still holds a charge, you can discharge it by shorting the terminals with a 100-Ohm resistor (re-check the voltage after doing this). DON'T hold the bare wires of the resistor. Solder some short leads to it first and insulate with heat shrink or insulated tape. Alternatively, use insulated pliers to hold it.
RECOMMENDATION: When you open the flash, do it on a soft surface to protect it and to keep little things like screws from rolling away. A mouse pad works nicely.
Step 2: Sensor and External Screws
CLEAR PC/sync socket
First thing you have to do is to unplug anything you have connected in the PC sync socket, like a slave trigger (see picture on intro page) or a sync cable.
Remove the auto thyristor sensor. It unplugs from the flash by pulling it away from the unit.
There ar 6 visible screws on the outside of the flash: 2 on the hotshoe, 2 on the swiveling head and 2 on the bottom of the "center hinge"
You will need a small set of (jeweler's) philips screwdrivers, like the ones used for eyeglasses repair. If you don't have a set, you can get them very cheap on ebay.
Remove the the 3 pairs of screws and note where they go as each pair of screws is different.
Very carefully separate the hotshoe from the unit a few millimeters is enough. Be careful with the wires as they could come off and would need re-welding.
Step 3: Side Aluminium Disc
Remove it carefully. with a thin flat screwdriver.
It is held by glue, try not to pry too hard in one spot to avoid bending or marking it.
Step 4: Remove Copper Coloured Clip
Remove the copper-coloured clip you just exposed under the silver disk by wedging a small flat screwdriver on the lower end.
Then carefully pull the swiveling head / hinge sides case apart (SEE THE 2 PICTURES BELOW).
Notice the way the cover for the flash head lines up, and more important the way the calculator dial is indexed by a little white plate with a bump on it. (this bump and a spring create the clicks as you turn the dial.).
On the opposite side, behind the cover held by the copper-coloured clip, there's a small white piece above a spring. This assembly create the clicks as you swivel the flash head. Be careful with the wite piece as it tends to fall off.
Step 5: More Screws!
My flash had 4 holes but 3 screws. Not sure if there should be 4 there, as my unit could have been disassembled by a prior owner that forgot to put one screw back. Just in case, check all holes with the philips screwdriver.
That's it, you're ready to open the bottom half by pulling the top and botom pieces apart. Be careful when you do this as there are a couple of plastic clips on the sides that could brake and you could disconnect a wire welded to a circuit board and could be tricky to find where it came off from.
You have now uncovered all the guts of the flash gun, ready for service or modification.
In my case, the PC sync socket had some springs bent out of shape. I reshaped them carefully with a couple of flat screwdrivers and thin pliers and tested that the slave trigger opened the connection correctly before putting the unit back together.
When re-assembling make sure you have all wires out of the way, and you don't pinch any when you close up any portion of the unit, and note that some of the boards fit into slots molded inside the top/bottom case.
Step 6: The Guts
Good luck and hope this instructable was useful.