I have opened up the base unit and one of the main power connections burned off the circuit board. Can the board be fixed or replaced?
One thing missing from my WMK300 is a
circuit breaker or replaceable fuse. Apparently your wiring became the fuse. Please read and understand my entire Answer before starting.
>>This answer is only for technicians proficient in soldering, with safety training in testing 120 VAC circuits and with an understanding of insulation temperature ratings. Memorize the average torque required to loosen each type of screw and do not exceed that torque when tightening.<<
It is likely that the wires leading to the heating elements are defective. You must open the top and bottom clamshells to inspect the wires inside there. Look for melted insulation, cracked stand-off insulation posts, etc. You will have to repair the obvious problems before the next steps.
>> It is helpful to have a multimeter to test resistance. The heating elements should not have continuity to the metal chassis or ground wire. The resistance of the heating elements should be in a sensible range given the wattage rating of this appliance.<<
If the wire under the damaged insulation is in great condition, you may just repair the insulation. In the base, you may use normal wiring insulation since this area stays cool. I recommend slipping some larger diameter insulation over the wire. (Strip this off a larger diameter wire.) In the hot clamshells, you must use high-temperature insulation like the woven fiberglass sheath used in toasters and ovens.
The two white heavy gauge wires connect to "N" (neutral) and "H2" (heater lead 2). The two black wires connect to "L" (line power) and "H1" (heater lead 1). If only one wire came off you should be able to find the correct solder point to reattach.
This circuit board is not replaceable and there are no components on the circuit board that should be capable of drawing enough current to melt the power wires. However, if you cannot find bad wiring elsewhere, inspect the circuit board for solder droplets, bits of wire, screws, bent components, etc. that may cause shorts. Look for overheated circuit board, traces or components.
>>To remove the circuit board on my WMK300, the temperature control knob is left intact on the control panel. Do not remove it. The circuit board lifts off the shaft of the control knob when it is removed from the chassis. Test the knob motion when mating it to the circuit board.<<
Almost all components except the potentiometer and the 8-pin microprocessor controller "U1" are easy to purchase online.
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