With all the hardware in place, the config.json file updated and the code installed, you are now ready to use the EZ Make Oven! Before we start reflowing boards, however, we need to do a dry run test to ensure the equipment is functioning and the components are communicating properly.
Verify the thermocouple is in the center of the oven at or near the rack where the PCB board will be placed. The close proximity to the PCB will ensure an accurate temperature reading. For a more accurate reading, taping the thermocouple to a PCB will measure the temperature at the PCB surface. This can be done using a high temperature tape such as Polyimide Tape (sometimes referred to by the brand name Kapton Tape). If the PCB board is too small or has no room, you can use a spare empty PCB and place it next to the PCB to be reflowed.
Once you have verified the connections and the placement of the thermocouple, press the "Start" button to begin the dry run. This will take a few minutes to run. You will see the oven go through several stages, including start, preheat, soak, reflow and cool down. There will be a short beep for each stage, ending with a long 5 second beep for the cool down stage and you can open the oven door.
You are now ready to use your EZ Make Oven. Need some help designing a PCB to use in your reflow oven? Look at this Adafruit Learning Guide for Eagle.
Is your oven not working as expected? Here are a couple of troubleshooting tips. If you still have a problem, you can ask a question in the Adafruit Forums.
The oven turns on, but the temperature goes down instead of up.
Your thermocouple wiring is backwards, swap the two wires on the MCP9600
The red circle oven indicator displays on the PyPortal screen, but my oven does not turn on.
Check that the relay light is on in the relay module. If not, check the cabling between the PyPortal and the relay. If the connection appears to be OK, you may have the wires backwards. Verify at the relay module that the white cable is on the left and the black cable is on the right.
Verify the oven controls are set properly. They should be set to maximum temperature, toast mode, and timer set to "always on". If the timer does not have that option, set it to the maximum time each time you use the oven.
The display shows "Bad/missing temp sensor"
This means the EZ Make Oven can not find the MCP9600 sensor used to measure the oven temperature. Verify the four wires of the I2C cable connecting the PyPortal to the sensors are connected properly. Also, verify the config.json file contains the correct I2C address for the sensor. This must be a decimal (not hexadecimal) value.
If these options do not help, you may need to change the power of the I2C port from 5 volts to 3.3 volts. This is done by cutting and soldering a trace in the back of the PyPortal near the I2C port. You can find more discussion on this at this link.
The PyPortal hangs on boot up
Temporarily unplug the MCP9600 from the PyPortal and reboot it. If it boots up properly, then you may need to change the power of the I2C port from 5 volts to 3.3 volts. This is done by cutting and soldering a trace in the back of the PyPortal near the I2C port. You can find more discussion on this at this link.