IV. Troubleshooting 7──back heating does not work
▲ Failure performance of heating function
1. No heating
2. Cannot stop heating
▲ Specific trouble shooting method
1. No heating trouble shooting method：
1) Heating fuse is damaged：See figure 28，the resistance value
of heating fuse in back cushion changes or open circuit will cause no heating.
The normal resistance is around 25Ω. If greater than 30Ω or open circuit will cause heating temperature
not enough or no heating. Replace heating fuse.
2). Heating power supply wire harness is bad contact: See figure 28,
power cord butt joint plug is bad contact will cause power can’t be delivered
to heating fuse. Replace it.
3). AC28V power failure: If ring transformer does not have AC24V output
or the power can’t be delivered from power supply board to main board
will cause no heating. Exclude it.
4).Main board is damaged: See figure 29,check “BCR5PM”controlled silicon,
“3150”optocoupler and“8650”patch triode in main board whether
are damaged. If yes, repair or replace main board.
Figure 28 back heating fuse
If the socket in above Fig. and plug in blow
Fig. are bad contact will cause heating fuse
non conduction. Or because of lack of spring
tension inside socket, or sealing-off or other
reasons may also cause non conduction
fault.
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