Monday 21 January 2019

A rework in progress

After the last repairs, I got sufficiently annoyed by the mess of wires around the extruder. In particular, having the extruder motor wiring as well as the fan wiring bypass the break-out PCB entirely made for a tangle as well as some rather unstable connections.


Extra wiring can be seen on the far side of the ribbon cable.
 I acquired new ribbon cable, D-Sub connectors (3 of them, just in case), and went to work. I only had to discard one of the D-Subs, and this time made sure to thoroughly test the connections. I cut the cables back to make for a neater lineup at the controller, and labelled the parts with Dymo labels this time (plastic, not paper, for fire safety).


Now having all this set up, the tests gave some rather disappointing results. For one, the thermistor and heater are connected, despite the instructions declaring - in boldface - that they shouldn't be. And indeed, the thermistor insists that my room is over 100C, which I am sure I would have noticed. The X motor and endstop work, but the extruder motor is making a strange faint clicking noise, even when doing nothing. Neither fan activates. This might take a bit to clean up - I even suspect the PCB itself has issues. The hour of remaking the PCB to include the proximity sensor draws near - and finally the otherwise unused cable #5 could come to the fore.

I'm rather concerned about the heater/thermistor connection, though, as it manifests on the controller board even when the heater is disconnected.

Update: The PCB appears to perform its functions exactly as advertised WRT the heater, thermistor, and motor. Disconnecting the ribbon cables from the controller board shows there's a ~1K connection from the lower HOTEND connector to the ETEMP connector.

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