163What to do when . . .First aid for faultsWhen a fault occurs, it is possible that this is the result of a small error, which you can remedy yourself using thefollowing notes.Do not carry out any other work yourself, if the information below does not help your specific problem.Repairs to the appliance must only be carried out by specialists. Improper repair work can result in conside-rable danger for the user. If you need repair work carried out, contact your specialist dealer, or our CustomerService department.What do I do when . . .. . . a buzzing noise is heard when a zone isheating up?-- This is not a fault.It will stop as the heat increases.. . . discolorations appears in the cooking zone?-- This is not a result of changes in the material, but isburned--in remnants that have not been regularly re-moved. They will have no effect of the function or thedurability of the ceramic hob.. . . the cooking zones do not function?Check whether-- the appliance is switched on,-- the control lamps are on in the operating field,-- the respective cooking zone is switched on,-- the cooking zone power level has been set to thedesired cooking--on level,-- the fuses in the house installation (fusebox) havetripped.If the fuses repeatedly trip, call in an approvedelectrician.-- the safety cut--out of the cooking zones has beentripped.. . . the cooking zones cannot be switched on?Check whether-- the operating field is locked,-- a time period of more than 10 seconds has expi-red between the operation of the On/Off key andswitching on the desired cooking zone,-- the touch surface is too large(the finger should only be used lightly)-- the touch switch has been partly covered by adamp cloth or by a liquid.-- the operating field has been touched too early fol-lowing a mains failure (to clear the condition,switch the fuse out and then in again).. . . the displays all go out except for the ”H” for resid-ual heat?Check whether-- the On/Off key has been accidentally operated,-- the touch switches are partly covered by a dampcloth, liquid or something similar.. . . the displays suddenly go out?Check whether-- the electricity supply has been temporarily dis-connected, or has failed.. . . after switching off, no «H» for residual heat is dis-played ?Check whether-- The cooking zone has only been in operation fora short time, and is therefore not hot enough.If the cooking zone is hot, please call in an approved elec-trician, or call our Customer Service department.. . . one of the cooking zones cannot be switched off?Check whether-- the touch keys are partly covered by a damp clothor a liquid.-- the corresponding cooking zone key (2) is active,i.e., the decimal point (13) is lit up.If you call in Customer Service as a result of one of theitems listed above, or as a result of incorrect operation,the visit of the Customer Service technician will not befree of charge, even during the guarantee period.