Unable to get hot end up to temperature, suspect Duet is marginal.

Commissioning my Ormerod 1, I have a couple of problems.

I'm trying to work out why my hot end won't respond. Applying a multimeter to the thermistor terminals at the board shows 139.4kOhm (Its about 18degC in here). If connect the board up and Connect to it with pronterface I get:

RepRapFirmware is up and running.
Printer is now online.
Temperature measurement fault on heater 1, T = -28.267216

Putting resitors across the pins and resetting then connecting pronterface to the board I get:a temperature readings
100k Ohm = 3.1 degC.
470 Ohm = 212.1 degC.

Should I persevere by heating the room before I continue, or should I get the better Duet board?

My next issue is I suspect the Y axis is somehow reversed. If I plug in the power supply, start pronterface, and press the blue Y Home button, it homes to the end away from the motor and end stop switch. Is this correct?

I would assume the Y would home the the other end where the switch is.

When I was building my Ormerod (2) I had trouble getting the duet to register the thermistor - eventually tracked it down to the connection at the duet end which was either not making proper contact or was in the wrong row of pins - the connector is not an easy fit IIRC.

Richard

Quote
ErroneousBee
Commissioning my Ormerod 1, I have a couple of problems.

I'm trying to work out why my hot end won't respond. Applying a multimeter to the thermistor terminals at the board shows 139.4kOhm (Its about 18degC in here). If connect the board up and Connect to it with pronterface I get:

RepRapFirmware is up and running.
Printer is now online.
Temperature measurement fault on heater 1, T = -28.267216

Putting resitors across the pins and resetting then connecting pronterface to the board I get:a temperature readings
100k Ohm = 3.1 degC.
470 Ohm = 212.1 degC.

Should I persevere by heating the room before I continue, or should I get the better Duet board?

This is a very common problem. Some solutions:

1. RRP has in the past replaced Duet boards under warranty where the ADC offsets are too far out to allow printing at normal room temperatures.

2. Work around the problem by warming up the hot end with a hair dryer. You will need to reset the temperature fault condition by sending M562 P1.

3. If you are experienced in SMD soldering/desoldering, get RRP's permission to change the 1K thermistor series resistors to 4.7K (as on the newer Duet boards) without voiding the warranty.

4. If you use my firmware fork, then you may get enough adjustment in the H parameter of the M305 command to eliminate the temperature error.

5. Connect a resistor of a few hundred Kohms in parallel with the hot end thermistor, choosing a value that gives you a reasonably correct reading at room temperature.

Quote

My next issue is I suspect the Y axis is somehow reversed. If I plug in the power supply, start pronterface, and press the blue Y Home button, it homes to the end away from the motor and end stop switch. Is this correct?

Two likely reasons for this:

1. You are using the version of homey.g and/or homeall.g meant for the Ormerod 2 printer instead of the O1.

2. Your Y endstop switch is not connected correctly. Test it by looking at the Y endstop LED on the Duet. It should normally be on, but should go off when you push the Y carriage all the way to the Y motor end.

Edited 1 time(s). Last edit at 01/10/2015 04:40AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].