Ice Tube clock: broken VFD tube lead -- need advice

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shmulkey
 
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Ice Tube clock: broken VFD tube lead -- need advice

Post by shmulkey »

While trying to slide the tube down onto the small PCB I broke one of the leads. Is there any way to reattach the lead to the tube, or do I need to purchase a replacement tube?

I found mating the tube to the small PCB very difficult. The leads kept bending and twisting, making it quite a struggle to advance the PCB up the leads toward the base of the tube. Aside from the standard advice to "take your time", is there any way to make this part of the kit construction less trying? Would it make sense to trim the tube leads down to an inch or less before feeding them through the holes on the PCB so that there's less chance of the leads bending? Would lubricating the leads (perhaps with liquid soap or wax) make it easier to feed them through the PCB holes?

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phild13
 
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Re: Ice Tube clock: broken VFD tube lead -- need advice

Post by phild13 »

How much of the broken lead is left on the tube or did it break off flush?

If there is no wire sticking out of the tube, then you will need a new tube.

There is a risk of breaking the tube when soldering very close to the base, so use the following at your own risk and wear safety glasses.
This should work if there is any wire at all sticking out of the tube and may work if you are careful if the wire broke off flush.

If there is any lead left sticking out of the tube, you can save that wire for last after all the others are done and soldered to make fixing it easier as things won't be moving around. Fix the tube (or tube board) in a vice or use another means to keep it very still while you work on it. Make sure there is no wax or contamination on the wire sticking out of the tube. Try to clean it by gently scraping if possible but don't do more damage to the wire. Warm the whole tube until it is hot with a hair dryer on high (or use a heat gun if you have one) to reduce the chance of breaking it from heat differential between the glass and the soldering iron tip which will be very close or touching the tube glass during the repair. If there is enough wire left sticking out of the tube, use tweezers to straighten the wire if it is not straight. Now stick a wire in the tube board hole, push it up to the tube base, lining it up with the broken wire on the tube. Solder that wire to the tube board to keep it in place and give some stability to it. Now using tweezers, line up this wire with the tube wire end. With a very clean tip, place a small drop of solder on the tip to aid in heat transfer, place the tip on the wires and touch the solder wire to the joint to add a bit of fresh solder. let it cool without disturbing the joint. You should now have a decent joint.


Installing the tube to the tube board:
Sometimes the tube wires have a bit of wax or something on them already.
Take your time, and don't be impatient. It might take an hour or more to install the tube on the board.

To thread the tube board I generally place the first wire in the hole for it with about 1/4 inch of wire sticking out the back. Bending this over about 90 degrees so it will stay. I then do each one in turn basically the same way making sure the wires go in the correct holes until I run out of wires. This gives me enough room to maneuver wires without excessively (the bends are not as sharp) bending them. Once I verify the wires are all in correctly and none are crossed, I slowly begin sliding the tube board up on the wires, pulling, wiggling the board and straightening wires as necessary until the tube is in the proper position. I never timed the process but it does take quite awhile to do.


I wouldn't cut the wires off short, as it will probably be harder and the risk of breaking a wire is higher. I kind of tried this when I damaged a tube board accidentally. I figured I would just use my hot air rework station to remove the tube from the damaged board and I could solder it back in to a new board. The tube came out of the damaged board easily enough and the wires were clean with no excess solder on them so they fit the holes in the new board easily enough. Should be simple to just install the tube on the new board right? After all the wires were already preformed. Well it wound up that it took about 3 hours to do and I was unsure if I was ever going to get the tube mounted to the new board.

shmulkey
 
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Re: Ice Tube clock: broken VFD tube lead -- need advice

Post by shmulkey »

PhilD13 wrote:How much of the broken lead is left on the tube or did it break off flush?

If there is no wire sticking out of the tube, then you will need a new tube.
It's broken off flush; I'll get a new tube. Fortunately, they are not too expensive. In the interim, I'll practice my tube installation technique on the old one. :-)

Thanks for the detailed and very helpful reply!

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adafruit_support_bill
 
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Re: Ice Tube clock: broken VFD tube lead -- need advice

Post by adafruit_support_bill »

Before ordering a new tube, double check exactly which lead is broken. If it is one of the No-Connection leads, consider yourself lucky. :)

Some have had good results trimming the leads so that they get progressively shorter as you go around the base of the tube. But I haven't found that technique to be especially helpful. What works for me is to straighten each lead individually (pinch it close to the base with one hand and then gently straighten it with the other.) Next, insert all the tips of the wires in the board. Once they are all threaded through the holes, gently work the board toward the base of the tube.

shmulkey
 
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Re: Ice Tube clock: broken VFD tube lead -- need advice

Post by shmulkey »

adafruit_support_bill wrote:Before ordering a new tube, double check exactly which lead is broken. If it is one of the No-Connection leads, consider yourself lucky. :)
I was lucky enough to get a tube without no-connections leads! :) I have ordered a replacement tube.
Some have had good results trimming the leads so that they get progressively shorter as you go around the base of the tube. But I haven't found that technique to be especially helpful. What works for me is to straighten each lead individually (pinch it close to the base with one hand and then gently straighten it with the other.) Next, insert all the tips of the wires in the board. Once they are all threaded through the holes, gently work the board toward the base of the tube.
Thanks -- that sounds like good advice.

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