The R nozzle temperature in touch screen does not change when start heating R nozzle. Fuse for R nozzle heater, R heating cartridges, R interconnection board, mainboard & cables inside umbilical track can cause this issue.
a. Re-plug J11 & J49 in main board.
b. Start heating R nozzle in touch screen, check the LED – DS12 (upper left corner of main board), if it’s off, means the fuse of it was broken. Replace the fuse.
c. Unplug J49 in main board, use meter to check if there’s short of circuit via the 2 pins of J49. If yes, check the cables from L interconnection board to 2 L heating cartridges. If there is wear on the cable which makes conductor wire exposed. Replace heating cartridges as needed.
d. Replace R interconnection board. Replace main board. Below figure is also a way to do troubleshooting on this issue.