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From Pumping Station One
Java Master 2002 Coffee Roaster (view source)
Revision as of 07:39, 10 November 2022
, 07:39, 10 November 2022→Maintenance
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Nota Bene:
- We have replacement gaskets and seals now for the roast chamber + venting tubes, etc.
- Chaff collector should be checked regularly, depending on frequency and scale of roasting. Not a big deal, but consider checking chaff collector before a new roasting session and/or after roasting several times in succession with beans that give off more chaff [e.g., ‘washed’ beans].
== Technical Details ==
== Technical Details ==
The roaster uses a Watlow PID controller (on the left) to control air temperature. It outputs a process value (4-20 mA), which an Avatar Instruments power controller uses to change the power to the heater via SCR phase dimming. The Avatar supports 240 V but the heater itself only can handle 208 V. This machine was designed to operate on 208 V but JavaMaster confirms it can operate on 240 V with an adjustment. Originally, JavaMaster suggested we limit the PID to 70% max output power. But that resulted in unexplained oscillations in temperature typically +/- 30 F. The Avatar includes an optional feature to limit output voltage via the V-LIM trim pot. This was adjusted so 100% on the PID corresponds to 208 V as measured by a true RMS voltmeter. Moving this back to 208 V will require re-adjustment of this trim pot.
The roaster uses a Watlow PID controller (on the left) to control air temperature. It outputs a process value (4-20 mA), which an Avatar Instruments power controller uses to change the power to the heater via SCR phase dimming. The Avatar supports 240 V but the heater itself only can handle 208 V. This machine was designed to operate on 208 V but JavaMaster confirms it can operate on 240 V with an adjustment. Originally, JavaMaster suggested we limit the PID to 70% max output power. But that resulted in unexplained oscillations in temperature typically +/- 30 F. The Avatar includes an optional feature to limit output voltage via the V-LIM trim pot. This was adjusted so 100% on the PID corresponds to 208 V as measured by a true RMS voltmeter. Moving this back to 208 V will require re-adjustment of this trim pot.
