Pulsar Calculator Missing Segment - Any Hope?

[bucko170]

I lost a segment from my Pulsar calculator watch, is there any hope for a repair?



Display looks good in this photograph - unfortunately it should read 5:29

[retroleds]

Well, fortunately that is one of the more widely spaced wire-bonding situations...there is probably a 70%+ chance of recover/repair. If repaired, you should have the display sealed for longevity.

[bucko170]

I figured it was going to be a wire bond at fault at least it sounds hopeful that it can be replaced

[azimuth_pl]

silver epoxy as always:


btw Ed,
which brand of silver epoxy are you using and what kind of silicone cover do you suggest buying? are these from Mouser?

[retroleds]

btw Ed,
which brand of silver epoxy are you using and what kind of silicone cover do you suggest buying? are these from Mouser?

I am using the MG Chemicals brand, available from Mouser - I like their package for a number of reasons. Unlike other brands which have short,wide tubes, their tubes are longer and thin - less settling of the silver and the plunger seems to work nicely all the way to the end of the tube. The wide ones seem to clog and then the plunger binds, leading too large amounts of epoxy being dispensed when you only wanted a drop but couldn't force one out. And the screw one tips keep things clean. The tips are [unfortunately] interchangeable, so I suggest you mark the top of the "black"(part B) tube with a marker, just to avoid a brain fart that ruins your epoxy.

For sealing wirebonds I use Devcon 24 hr epoxy(I use Devcon 5 minute for most other repairs, glass-setting,etc.....the tips only go on one way, so no way to screw up and glue the cap on by reversing things.). The 24 hr. stuff is thinner(less viscoisity), so it flows good between and around the wire bonds - a drop at a time, it also allows lots of time for any bubbles to reach the surface easier. I cheat a little on the bubbles by using a vacuum pump and a clear polycarbonate vacuum chamber ....a few minutes at 15-20 bar draws 99% of the bubbles to the surface where they either pop or I gently pop them by lightly rolling a cotton q-tip across the surface(wicking off some of the excess epoxy). Due to the hump of epoxy you get a very slight magnifier effect - bonus!. I don't use acrylic nailpolish, polyurethane or silicone - all of those have a high percentage of shrinkage which could actually rip wire bonds loose and silicone is acidic until cured. I've never seen a very clear silicone.