Brother LH4-B800E Service Manual page 164

Code
1. Clean the exhaust cooling fan. (Remove dust.)
2. Check if connectors P1 and P20 on the main circuit board are securely inserted and if any
harness is broken or short-circuited.
3. Turn power off, check if connectors CN2, CN3 and CN4 on the 1-step power supply circuit board
E-42 are securely inserted and if any harness is broken or short-circuited.
* OK if 17 V AC is present between pins 4 and 5 of connector P20 on the main circuit board.
If not OK, replace the transformer.
4. Replace the cooling fan.
5. Replace the main circuit board.
1. Check if connector P3 on the sub circuit board is securely inserted and if any harness is broken
or short-circuited.
2. Check if connector P3 on the 2-step power supply circuit board is securely inserted and if any
harness is broken or short-circuited.
3. Check if connectors P10 and P13 on the sub circuit board are securely inserted and if any
E-44 harness is broken or short-circuited.
4. Check if connectors P22 and P23 on the main circuit board are securely inserted and if any
harness is broken or short-circuited.
5. Replace the 2-step power supply circuit board.
6. Replace the sub circuit board.
7. Replace the main circuit board.
E-51
1. Turn off the power and initialize the settings.
E-52
1. Automatically resets after 2 minutes. (Sewing data of 3,000 stitches or less will be valid, and any
E-54
sewing data past the 3000th stitch will be invalid.)
1. Turn off the power and then back on again. (Zigzagging and bar tacking will automatically be
halved, so the error display will disappear.)
E-55
2. If error E-55 appears again after the above operation is carried out, turn off the power and
initialize the settings.
1. Turn off the power and initialize the settings.
E-59 2. If error E-59 appears again after the above operation is carried out, replace the man circuit
board.
Countermeasure
LH4-B800E
6. ELECTRIC MECHANISM
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