20 Most Recent Sharp R-1874 Convection/Microwave Oven Questions & Answers

I had the same problem. Turned out to be the micro switch and damper motor. I replaced both myself and fixed the problem for less than $40.00. The best advice I got was replace the switch, reconnect the motor and make sure the motor runs through a damper door cycle. It didn't run, even though it showed continuity and had power, so I replaced the motor which solved the problem. The micro switch which is activated by the cam on the damper motor has to be cycled within one minute, or the unit shuts itself off. The damper motor on my model R-1870 is found in the right rear section of the assembly when facing it. You have to remove the unit, and remove the outer casing to get to it. The damper is a simple sheet metal door, activated by the motor, and the switch mounts at the top of the motor and is activated by the same cam that activates the door.

Possibly a bad oven temp sensor. If the uinit doesnt read a temperature it will shut down to prevent a fire or over heating. The temp sensor is a thermister A temperature variable resistor that changes value as the temp changes. so If the main board doesnt get a response within a vertain resistance range it shuts things down. Sometimes since those parts are in the actual cooking area and subject to the heat and steam from cooking they can rust and break, or just get old and break. Or slam the door and break, you get the idea!!

I have exactly the same problem; always after 59 secs, it stops.

This is a problem in one of the damper-related components, either the switch or motor or the damper door may be binding.

The damper is a door inside that opens or closes depending on cooking mode. If the controller senses that the door is not in the right position, it will shut down the cook cycle.

Sharp models stop after 59 seconds.

See the attached sample drawing for a typical damper assembly.

We have the applicable service manuals for these models and have uploaded them to our site here, here and here to help you.

If a switch is all you need, we offer a universal type for only $5 postpaid which you can order here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

change damper motor and switch. cost is approx $30.00. unit must have cover removed to gain access to motor & switch
Bob

Don't know if this a regular problem with this unit, but for this fuse to blow, there must be a problem further downstream. Maybe with the power supply or the Magnatron.

This looks that the motor is not being functional, for that you have to look for the fuse if one. or else check the circuit if any wire is disconnected or burnt out accordingly you can decide what needs to be done.

Your connection is bad. Start with a good and complete cleaning of the product. UNPLUG FIRST. Sometimes in the hinges things gum it up. DO NOT STICK anything into the door latch area. If this continues, you have an issue that must be decided if you should REPLACE or repair. Repair will cost more than replacing. Sorry.

I would say the mount for your bottom or top door switch is loose, misaligned, or broken. And you may have a failed door as well. See my help file on door switches here. Slamming the door and opening the door while it's cooking instead of hitting the "Stop" pad before opening it both contribute to door switch trouble. The service manuals covering this model are here and here. You can order Sharp parts from Encompass here or you can call them toll-free at 866-779-5835.