Medtronic Button Error Troubleshooting¶
Medtronic insulin pumps sometimes develop problems with their buttons; this seems to be the most common type of failure for older Medtronic pumps. If you have a pump which has lost the sticker that covers the buttons, which has a button that doesn’t respond, or which displays a “button error”, it is likely repairable.
NOTE: Before attempting to repair an insulin pump, have a plan for what to do if the repair fails, or if the pump stops working some time later. This may mean carrying a spare pump, or a vial of insulin and syringes. If your pump has failed and you don’t have a backup, don’t try to repair it until you’ve solved the immediate problem by gotting an alternative in place and stabilizing your blood sugar. If a pump has had a button fail and been repaired, it’s much more likely to have another button problem than a pump which has never had a button problem in the first place.
There are two symptoms of button problems: either the button doesn’t respond when you press it, or it registers a press when you didn’t push it. If a button is held for three minutes continuously, the pump will report a Button Error; to clear a button error, you need to press ESC then ACT, which may be difficult if the failing button is one of those two. The ACT button is the one most likely to have a problem, because it gets pressed the most times during normal use. According to Medtronic’s documentation, the pump will not deliver insulin (including basal) until the error is cleared.
The button assembly on a Medtronic pump consists of:
- A brown circuit on the bottom
- Five metal snap-domes resting on each of the five button positions
- A piece of adhesive film (similar to scotch tape), which keeps the domes from moving sideways
- A plastic sticker, which keeps out moisture and provides labels
To make a repair, the first thing you’ll need to do is peel up the sticker. Start from the corner above and to the left of the quick-bolus button; if it doesn’t come off easily, you can stick a knife with a pointed tip in the corner. Next you’ll want to peel up the adhesive film, again starting from the left.
Once the sticker is up, you’re looking for three things: domes that have moved sideways and aren’t centered on the contacts, domes that are crushed and aren’t popping back up, and domes with gunk or corrosion in between them and the contacts. If there is gunk under the buttons, use a Q-tip to clean it off. If that doesn’t work, try isopropyl alcohol.
After being pressed enough times, the metal domes will eventually develop metal fatigue and get crushed, leading to a button error. As a temporary fix, you can peel up the sticker and tape, press on the dome from bottom, popping it back up. However, once this has happened, once, it will keep happening again, so you’ll want to replace the dome. You can replace them with these domes from Digikey.
When the sticker has been peeled up, it might retain enough stickiness to put back, or it might not. If it doesn’t stick back down, applying a thin line of cyanoacrylate glue (aka Krazy Glue) around the perimeter of the sticker will work. Test all the buttons before gluing, as it will be difficult to get the sticker back off once you’ve done this.
If you’ve lost the sticker or the sticker has lost enough of its adhesive to be a problem, you can replace both the film and the sticker with this material. Cut a piece in approximately the shape of the sticker; hold it against the pump to see which edges needs to be trimmed further, and repeat until you have a piece in the same shape as the sticker.