When I was a young boy my parent's alarm-clock (already old at that time) stopped working. Once opening it I found a beautiful huge display but since I was a bit silly I didn't desoldered it, neither I left long pins, but to "refine" the edges I filed away every trace of pins. Now it's time to build a clock from it, so I wanted to fix it and recover all the snub pins from the flat surface of the glass.
I'll explain you an effective way which worked good in my case, and it can be applied in many similar situations.
Step 1: The Patient
That display is actually a beautiful VFD (vacuum fluorescent display
) display, the model is 4-LT-16 9L
by Futaba, and it's also probably valuable and rare since I couldn't find it on eBay, and either no references on the web. The four digits are 1.5 cm high, which is very big for a VFD display (LEDs were still at their first stage of life, tiny red glowing diodes).
Step 2: The Polishing
You need to clean the metal of the pins (the bit you can see) with a very fine-grained sand-paper, but pay attention to not remove any significant portion of pins. Then add over all pins area a small amount of soldering-paste, to do that use something sharp as a toothpick, and check that paste covers every single pin.
Leave some minutes the paste acting as solvent in cleaning pins surface.
Step 3: The Critical Step
This is the most critical step of the entire process, since you are soldering something at direct contact with a glass vacuum tube. The heat creates differences of temperature inside the glass, so that the volume changes in adjacent portions and the glass could break.
For this reason you have to be very fast in applying tin with your soldering iron on the external tiny surface of each pin. Then wait some seconds before proceeding to the adjacent pin. If the operation fails, put your iron away, clean the pins surface, add more soldering paste and try again, don't be hurry.
If you look at the pictures closely you'll see that each pin is now covered with a small layer of tin.
Step 4: The Funny Step
I've tried to use some IDE flat cable
to connect pins, but when you move a wire you accidentally detach the already soldered wires... so you have to find many single wires, with multi-filament core, the more flexible you're able to obtain.
Apply some tin on the wires end, then solder them one by one to the pins. Again, be very fast, and don't move the soldered wires for now.
Step 5: Gluing
The wires are now all in place, kept steady by the tin, so that you're sure the connections are all perfect, actually there is no chance that you could solder a wire to the glass.
The problem now is that each movement of the wires could detach the connection. To avoid that I decided to glue all the wires ends on the display edge with a two-component powerful glue.
So all the pins on the crowded side are joined together and a movement of a single wire doesn't reach the pin.
Step 6: And Gluing
You can also add more glue layers, waiting that they dry before applying the next one. The more glue you add the more sturdy the connection will be, but also glue will be more visible if you'll leave your display with no case or with a transparent one...
Step 7: Ready to Be Powered
My wires are very long, since I'm not sure how to build my clock. The longer the wires are, the safer will be working on the free ends, as soldering them on a pcb, inserting them into a breadboard, etc.
All right, this orange creepy bug is ready for the clock project, I hope you can save your own old electronic component in same way (maybe you also kept some interesting object for so many years...).