Display reader short on circuit board - GE Spacemaker JVM1640SJ Microwave Oven

The 8888 error code may result from overheating, internal short circuits, or issues with the main control board. The entire display control board may need replacement.

I recommend contacting Kambrook directly to inquire about replacement. The burning of the magnetron, a critical component in microwaves, can also trigger error codes.
If the magnetron is faulty, it could lead to the 8888 display. Sorry, the possible multiple causes make this hard to diagnose.

You haven't identified the brand, make or model but this may be helpful:

Newer Panasonic Microwaves have built in fault codes....

they look like H97, H98....
Troubleshooting of Inverter Circuit (U) and Magnetron
This oven is programmed with a self diagnostics failure code system which will help for troubleshooting, H97, H98 and H99 are the provided failure magnetron and inverter circuit problem areas. This section explains failure codes of H97, H98 and H99. H97, H98 and H99 appears in display window a short time after start key is pressed and there is no microwave oscillation.


NOTE:
DO NOT try to REPAIR this Inverter Power Supply (U) and also DO NOT RE-ADJUST PRESET VOLUME on the board. It is very dangerous to repair or adjust without sufficient test equipment because this circuit handles very high voltage and very large current. Off alignment or inverter board operation is dangerous. Operating a misaligned inverter circuit is dangerous due to the very high voltage and current that is produced by this board. Defective boards must be replaced with a new one.
- Check magnetron filament for open or short to casing before proceeding to determine a good magnetron.
Alternative way to troubleshoot oven with AC Ampere meter used.
H97, H98 and H99 appears in display window a short time alter start key is pressed and no microwave oscillation with AC Ampere meter used for troubleshooting.


NOTE:
DO NOT try to REPAIR this Inverter Power Supply (U) and also DO NOT RE-ADJUST PRESET VOLUME on the board. It is very dangerous to repair or adjust without sufficient test equipment because this circuit handles very high voltage and very large current. Off alignment or inverter board operation is dangerous. Operating a misaligned inverter circuit is dangerous due to the very high voltage and current that is produced by this board. Defective boards must be replaced with a new one.
- Check magnetron filament for open or short to casing before proceeding to determine a good magnetron.

check the touch pad or control unit any short circuit in the control unit, other wise any moisture at control unit chec the circuit other wise replace the touch pad.

<- Let me know your full model number from the tag on your oven so I can give you detailed information repair.

Unless there is grease or moisture on your control circuit board, "SE" means you have a shorting membrane keypad.

Possible that the display unit or the main processor unit is faulty; It is possible that insects could have nested within and produced accumulation of dirt within the circuits to dampen and short the circuit. Remove front panel and clean , use dryer to warm. If the fault persists it can be due to faulty or weak LCD.

your have problem with the controller board circuit, you driver or relay is shorted that why it start automatic. You may replace it with new board or trouble shoot the board.

H97, H98 and H99 appears in display window a short time alter start key is pressed and no microwave oscillation.

NOTE:

DO NOT try to REPAIR this Inverter Power Supply (U) and also DO NOT RE-ADJUST PRESET VOLUME on the board. It is very dangerous to repair or adjust without sufficient test equipment because this circuit handles very high voltage and very large current. Off alignment or inverter board operation is dangerous. Operating a misaligned inverter circuit is dangerous due to the very high voltage and current that is produced by this board. Defective boards must be replaced with a new one.

H97, H98 and H99 appears in display window a short time alter start key is pressed and no microwave oscillation.

NOTE:

DO NOT try to REPAIR this Inverter Power Supply (U) and also DO NOT RE-ADJUST PRESET VOLUME on the board. It is very dangerous to repair or adjust without sufficient test equipment because this circuit handles very high voltage and very large current. Off alignment or inverter board operation is dangerous. Operating a misaligned inverter circuit is dangerous due to the very high voltage and current that is produced by this board. Defective boards must be replaced with a new one.

- Check magnetron filament for open or short to casing before proceeding to determine a good magnetron.

hi, have you changed the fuse in the plug, if the starter has shorted out then the chances are you will keep shorting out untill you replace the starter.
If you have replaced the fuse and you still have no power then the chances are you have blown the circuit board if this is the case then this would need testing and any parts replacing.
The problem with doing this is you would need a copy of the schematics and also testing equipment to test the board .

Let me nkow how you get on or if you need further assistance ok

Not sure about the Neff brand, but in general you'd want to check for 110VAC power on the primary side of the low voltage transformer on the control panel / board. If that is present, check the secondary for voltage, about 12-30VAC. If the unit has a VFD type display, there will be a heater filament supply, usually around 2.5-6VAC. Also look for bad connecitons on the VFD. If those voltages are present, check connections on the board, look for bloated / bulging capacitors, shorted diodes, breaks in the board, etc. Also look for thermal cutouts and thermostats. If this doesn't fix it, can you take several photos of the inner parts and circuit boards?