Thread: Sharp MX-4501N, H4-02

upgrade the firmware or replace the defective thermostat. There may have been an update to move that thermostat a little further away from the roller with washers.

not looking in my SM but off the top of my head. h4 02 is a specific heat lamp low temp signal. First thing is set all heat temp values back to factory defaults. Sharp always run best there . Don't change from factory settings (unless your talking about sharps horrible c dragon machine) 2nd look in book and find exact lamp that that code is for .Then replace that thermistor , heat lamp, check all conections to it ,temp breaker canister then the ac triac that is on the ac pwb that controls the large ac current to the lamp from a small dc signal generated from the pcu pwb to control it all. That's it it simple! I'm remembering that it uses a triple lamp setup 1) end filiments for 11" paper width and 2)center filament for 8.5 and 3) a warmup lamp to facilitate quick warmup...3 lamps 3 thermistors 3 triacs 3 control curcuits. I think by memory not looking in book.