Lexmark T65X -- Burnt Fuser Lamp Terminal

I pulled the fuser out of a functioning T650 the other day, and was greeted by a very nasty looking left side end lamp terminal. I propped up the end of the fuser on a rigid surface so I could really bear down with a screwdriver, and the screw broke off, like so.

I imagine what happened here is that the screw had been installed only finger tight, and the resulting electrical connection was good enough to work, but resistive enough that it heated up something fierce. Eventually, it got hot enough that it effectively spot-welded itself together and continued to work. I had to peel the lamp's terminal off with a knife blade.

This sort of thing is usually repairable. The key to it is getting the seized screw end drilled through, and the key to that is getting a good, dead-centre centre punch impression in the screw. Easier said than done, but I got lucky.

A 7/64" drill in the drill press took care of the screw remnant, and left me with a hole just a little undersize for an M3 screw. I ran an M3 threading tap through it to create a vestigal thread, and rounded up the bits I'd need to refasten the terminal. Here's a view of the repair almost done.

The terminal's been well scraped. A small diameter sanding drum in a hand grinder took care of the bubbled, bloated plastic by the terminal.

The screw is 14 mm long; I cut down a longer screw to obtain that length. (The screw must be no longer than necessary so it won't interfere with inserting the fuser in the printer.)

And after a good scraping of the lamp's terminal, it was all ready to go back together, like so.

That'll work fine.

If I were doing this again, I'd drill a clearance-diameter hole for the screw and not bother with threading an undersize hole. There's really nothing gained by doing that.

In any event, the lesson is to be certain that lamp terminal screws are good and snug. Those lamps draw a lot of current, and they need good, low-resistance connections to draw it through.

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