Print Unable 78 Code – Brother HL – 4140, 4150, 4570 Color Printers
Diagnostic Tips for the Brother HL – 4140, 4150, 4570 Print Unable 78 Code
Like the Print Unable 78 Code is like the 76 code but the exact opposite. Instead of the thermistor reading a sudden sharp increase in the fusing unit the print unable 78 code is a sudden decrease in temperature in the fusing unit. Both errors are similar in the fact that they are usually caused by a sudden loss of power. This last weekend we had strong winds and our power went off and on several times. Some of our electronics reset and other didn’t. I also see lots of these errors right after strong lighting storms. Anytime we have them in our area the next day I usually get a call or two with customers having one of these errors.
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When these machine get that sudden loss of power, they tend to want to go out and immediately check the temperature of the fusing unit. The temperature in the fusing unit is precisely timed and measured. In this case the machine thinks it should be at a ready state. If at the time of the power outage the machine was in a sleep mode then it compares it to a ready mode and says the temperature is way under what it should be. Most times these errors can only be reset by putting it into maintenance mode. Below I will give you a few troubleshooting tips along with a link to the fuser error code reset procedure and instructions on how to remove and replace the fusing assembly if needed.
Troubleshooting Tips for the Print Unable 78 Code
1. Turn the machine off then back on.
2. Turn the machine off, unplug all the cables (power / communication), let the machine sit 15 to 20 minutes, plug back in and try again.
3. Click on the link below to try to manually reset the fuser error code. 95% of the time this step will fix the problem
Fuser Error Code Reset – Brother HL – 4140, 4150, 4570 Series
4. Remove the fusing assembly and check the lamp, thermostat, and thermistors, re-seat the connectors and try again.
5. Replace the fusing assembly.
Note: If you replace the fusing assembly don’t forget to reset the fuser life counter.
Click on the Link below for Fuser Removal on these machines
Brother HL 4140, 4150, 4570 Fuser Assembly Removal and Reset Procedure
Click on the Link below for buying options and additional details on the  LY0748001 Fusing Assembly
