Wet null voltages

1. A system, comprising:

a power supply electrically coupled to an electrode, a developer roller, and a cleaner roller; and

a controller to:

instruct the power supply to reduce, at a first time, a magnitude of an electrode voltage supplied to the electrode, and

instruct the power supply to set, at a second time, a developer roller voltage and a cleaner roller voltage each to about a wet null voltage,

wherein the wet null voltage causes liquid carrier to be transferred from the developer roller to a photoconductor, and wherein the photoconductor is to transfer the liquid carrier to an intermediate transfer member.

2. The system of claim 1 , wherein the controller is to wait a predetermined time between the first time and the second time.

3. The system of claim 2 , wherein the predetermined time is based on a geometry of the developer roller and a modification time to reduce the electrode voltage.

4. The system of claim 1 , wherein the controller is to instruct the power supply to reduce the electrode voltage to about match the developer roller voltage at the first time.

5. The system of claim 4 , wherein the controller is to instruct the power supply to set the electrode voltage to about the wet null voltage at the second time.

6. The system of claim 1 , further comprising the cleaner roller, wherein the cleaner roller is to remove developed printing fluid from the developer roller between the first time and the second time.

7. The system of claim 1 , further comprising the developer roller, a photoconductor, and an intermediate transfer member, wherein the developer roller is to transfer liquid with few or no solids to the photoconductor while the developer roller is at the wet null voltage, and wherein the photoconductor is to transfer the liquid to the intermediate transfer member.

8. A method, comprising:

reducing development of printing fluid on a developer roller in contact with a photoconductor;

cleaning developed printing fluid from the developer roller;

reducing a potential difference between the developer roller and the photoconductor to transfer liquid carrier with few or no solids to the photoconductor; and

transfer the liquid carrier with few or no solids from the photoconductor to an intermediate transfer member.

9. The method of claim 8 , wherein reducing development of printing fluid includes reducing a potential difference between an electrode and the developer roller and reducing a potential difference between a squeegee roller and the developer roller.

10. The method of claim 9 , wherein reducing development of printing fluid includes waiting a predetermined time after reducing the potential difference between the electrode and the developer roller before reducing the potential difference between the squeegee roller and the developer roller.

11. The method of claim 9 , wherein reducing the potential difference between the electrode and the developer roller comprises reducing the potential difference between the electrode and the developer roller to about zero, and wherein reducing the potential difference between the squeegee roller and the developer roller comprises reducing the potential difference between the squeegee roller and the developer roller to about zero.

12. The method of claim 8 , further comprising reducing a potential difference between the developer roller and a cleaner roller to about zero.

13. The method of claim 8 , further comprising initially determining a wet null cycle is to occur.

14. The method of claim 8 , further comprising transferring liquid from the developer roller to the photoconductor with limited solids transferring, and transferring liquid from the photoconductor to an intermediate transfer member.

15. A non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to:

determine a wet null cycle is to occur;

perform a wet null cycle, wherein the instructions to perform the wet null cycle include instructions that cause the processor to:

wait for a developer roller in a developer unit to be cleaned; and

indicate to a power supply to change a cleaner roller voltage to about a developer roller voltage.

16. The computer-readable medium of claim 15 , wherein the instructions, when executed by the processor, cause the processor to:

indicate to the power supply to change the developer roller voltage to about a wet null voltage after waiting; and

indicate to the power supply to change the cleaner roller voltage to about the developer roller voltage by indicating to the power supply to change the cleaner roller voltage to about the wet null voltage.

17. The computer-readable medium of claim 15 , wherein the instructions, when executed by the processor, cause the processor to indicate to a power supply to change an electrode voltage and a squeegee roller voltage to about the developer roller voltage based on the determination the wet null cycle is to occur.

18. The computer-readable medium of claim 17 , wherein the instructions, when executed by the processor, cause the processor to, after the indication to change the electrode voltage, wait for developed printing fluid to be squeegeed before indicating to the power supply to change the squeegee roller voltage to about the developer roller voltage.

19. The computer-readable medium of claim 15 , wherein the instructions, when executed by the processor, cause the processor to wait for the developer roller to be cleaned by waiting a predetermined time.

20. The computer-readable medium of claim 15 , wherein the instructions, when executed by the processor, cause the processor to determine the wet null cycle is to occur by receiving an interrupt.

21. The computer-readable medium of claim 15 , wherein the instructions, when executed by the processor, cause the processor to cause heat and charge to be delivered to the intermediate transfer member during the wet null cycle.