Don't forget to check your connectors!

Had a print fail midway last night, klipper detected the bed temp falling despite 100% throttle and aborted.

Did a little digging and found the culprit:


v2 heated bed without the pogo pins, has been printing perfectly fine for almost 4 years without any issue or maintenance required. Given that all 3 of the positive pins are melty, the contacts probably just tarnished from age over time and increased their resistance.

Yet another part of the stock R2 gone... Desoldered the connector from the heater PWB and soldered in 14awg wires for the bed heater and another smaller wire pair for the thermistor. I wired in a disconnect point under in the electronics cabinet, JST-SM for the thermistors and an XT60 for the bed heater itself. Shouldn't need to worry about it going bad for awhile!

 

The designers were clever but inexperienced. Connectors current ratings are specified for a temperature rise at a current. When you mount a connector to a plate that may be 70C to begin with the current rating must be derated. The socket contacts are oxidizing at an accelerated rate. Once one contact has it's resistance start to rise the remaining contacts have increased current and the failure cascades.

I cut the connector off and soldered directly to the bed. I then purchased a Flexplate system and glued microporus glass to the flexplate for easy removal and a flat surface. This is the only way I can prevent connector failure, as I have the R2's printing 24/7.

 

Can tell it's been on its way out for awhile, my bed heats considerably faster now than it has for at least the last month or two.