Troubleshooting Th2 temperature or coolant failure problems

Troubleshooting Th2 temperature or coolant failure problems on a Lotem 800 Quantum

Product

Thermal 2 head
Coolant pump

Errors

[02321] Laser Diode: The laser diode is over-temperature ( WLP fault )
[02325] Laser Diode: Possible coolant failure ( WLP fault )
[02323] Laser Diode: The temperature sensor is open-circuit ( WLP fault )

Symptoms

The errors listed above may appear.
When you use the command ldd info to check the temperature of the diode, you see the line laser temperature not available 0 C. See the sample code.
Note: This does not mean that the TH2 head has to be replaced. This indicates that the temperature information is not available because the WLP is in a reset state. This ensures that the head is not damaged by high temperatures.

CAUTION: Before attempting to turn the laser on or off again, check all other possibile causes for the temperature problem, such as low coolant level, pump failure, and so on.

Cause

The head is not normally the cause of these types of errors. The most common causes are:

There is not enough coolant.
The air filter is not clean.
The pump has failed.
The coolant strainer is plugged.
For TH2 heads with serial number 300 or less, the coolant path may be blocked due to corrosion.

For more information, refer to the system diagram (this link expands)

The reservoir contains the coolant liquid, and the pump circulates this coolant through a radiator. The air circulating through the air filter and radiator reduces the temperature of the coolant. Then the coolant goes through the head and gets cycled back to the reservoir. At the top of the reservoir there is a coolant filter.

A pump failure will stop the coolant from circulating causing a temperature increase inside the head. Lack of coolant or plugged air filters may have the same effect.

Solution

Error displayed Solution

[02321] Laser Diode: The laser diode is over-temperature (WLP fault)
[02325] Laser Diode: Possible coolant failure (WLP fault)

Check the coolant level, check and repair any leaks in the hoses and o-rings. Top up the coolant, if necessary.
Inspect the air filter. Replace the filter as needed.
Test the function of the coolant pump. Use the following procedure: How to check the coolant pump
Inspect and clean the coolant strainer. The strainer is located at the top of the reservoir. For More information see:
- Strainer Preventive Maintenance
- Regional Jigs Kit for Lotem 800 Quantum 510J6L042
If you're working on a TH2 heads with a serial number of 300 or less, check the coolant path. It may be blocked due to corrosion. Follow this procedure.

[02323] Laser Diode: The temperature sensor is open-circuit ( WLP fault ) Replace the head.