• Code: E020-0390
• Description: Patch (C) density lower limit error. The ATR patch detection output (SigD) is less than 79.
• Remedy: • When the value of COPIER> DISPLAY> DENS> P-LED-DA is large (153(D) or more) and the value of P-SENS-P is small, there is a high possibility that dirt is applied to the patch sensor. • This occurs only at a regular timing. When the value of COPIER> DISPLAY> DENS> DENS-S-x is small (2 digits), there is a high possibility that breaking occurred. 1. Check whether the developing assembly and the drum unit are properly installed. 2. Clean the patch sensor (PS21) . 3. Check the connection between the patch sensor and the Drum ITB driver PCB (UN6). (Connector, Shorting) Sensor side: J7412, J8035 PCB side: J1907 4. Check open/close operation of the patch shutter. 5. Check whether scratches/dirt are applied to the ITB. If many scratches are found, replace the ITB. If dirt is applied, clean the ITB. In this case, check the ITB cleaning blade at the same time. 6. Replace the patch sensor unit. NOTE: This error also occurs when there is not enough toner in the developing assembly. In this case, check the supplyrelated parts in the developing assembly

• Code: E020-0391
• Description: Patch (C) density upper limit error. The ATR patch detection output (SigD) is more than 970.
• Remedy: • When the value of COPIER> DISPLAY> DENS> P-LED-DA is large (153(D) or more) and the value of P-SENS-P is small, there is a high possibility that dirt is applied to the patch sensor. • This occurs only at a regular timing. When the value of COPIER> DISPLAY> DENS> DENS-S-x is small (2 digits), there is a high possibility that breaking occurred. 1. Check whether the developing assembly and the drum unit are properly installed. 2. Clean the patch sensor (PS21) . 3. Check the connection between the patch sensor and the Drum ITB driver PCB (UN6). (Connector, Shorting) Sensor side: J7412, J8035 PCB side: J1907 4. Check open/close operation of the patch shutter. 5. Check whether scratches/dirt are applied to the ITB. If many scratches are found, replace the ITB. If dirt is applied, clean the ITB. In this case, check the ITB cleaning blade at the same time. 6. Replace the patch sensor unit. NOTE: This error also occurs when there is not enough toner in the developing assembly. In this case, check the supplyrelated parts in the developing assembly.

• Code: E020-03A0
• Description: Toner density sensor (C) output lower limit error. The toner density sensor output (Vsig_ind) is less than 43
• Remedy: 1. Check the connection between the toner density sensor and the DC controller PCB. (Connector, Breaking (shorting)) <Y> sensor side: J7133, J8028, J8087 PCB side: J1244, J8085 <M> sensor side: J7134, J8029, J8088 PCB side: J1244, J8085 <C> sensor side: J7135, J8030, J8089 PCB side: J1244, J8086 <Bk> sensor side: J7146, J8015, J8117 PCB side: J1244, J8080 2. Check whether disconnection or shorting of the toner density sensor occurs or not. 3. Replace the developing assembly

• Code: E020-03A2
• Description: Toner density sensor (C) output upper limit error. The toner density sensor output (Vsig_ind) is less than 247
• Remedy: 1. Check the connection between the toner density sensor and the DC controller PCB. (Connector, Breaking (shorting)) <Y> sensor side: J7133, J8028, J8087 PCB side: J1244, J8085 <M> sensor side: J7134, J8029, J8088 PCB side: J1244, J8085 <C> sensor side: J7135, J8030, J8089 PCB side: J1244, J8086 <Bk> sensor side: J7146, J8015, J8117 PCB side: J1244, J8080 2. Check whether disconnection or shorting of the toner density sensor occurs or not. 3. Replace the developing assembly

• Code: E020-03C2
• Description: Patch (C) sampling error. The variation before average patch P wave light intensity is more than 100.
• Remedy: 1. Check whether the developing assembly and the drum unit are properly installed. 2. Clean the patch sensor (PS21). 3. Check the connection between the patch sensor and the Drum ITB driver PCB (UN6). (Connector, Breaking (shorting)) Sensor side: J7412, J8035 PCB side: J1907 4. Clean or replace the ITB. • Check whether the ITB belt is dirty or not. If it is dirty, perform cleaning with the service mode (COPIER> FUNCTION> CLEANING> TBLTCLN). • If it is assumed that this error occurred due to scratches on the ITB, replace the ITB. 5. Replace the patch sensor unit. 6. Replace the developing assembly. (Check whether there is not uneven coating on the developing sleeve.)

• Code: E020-0420
• Description: Initial installation toner density sensor (Bk) output lower limit error. When executing the developing assembly initial installation mode (COPIER> FUNCTION> INSTALL> INISET-K), the output level does not reach 128 even when control voltage of the toner density sensor reached 255 or more
• Remedy: 1. Check the connection between the toner density sensor and the DC controller PCB. (Connector, Breaking (Breaking (shorting))) <Y> sensor side: J7133, J8028, J8087 PCB side: J1244, J8085 <M> sensor side: J7134, J8029, J8088 PCB side: J1244, J8085 <C> sensor side: J7135, J8030, J8089 PCB side: J1244, J8086 <Bk> sensor side: J7146, J8015, J8117 PCB side: J1244, J8080 2. Check whether disconnection or Breaking (Breaking (shorting)) of the toner density sensor occurs or not. 3. Replace the developing assembly

• Code: E020-0424
• Description: Initial installation patch (Bk) density lower limit error. When executing the developing assembly initial installation mode (COPIER> FUNCTION> INSTALL> INISET-K), the ATR patch detection value (SigD) is less than 79
• Remedy: • When the value of COPIER> DISPLAY> DENS> P-LED-DA is large (153(D) or more) and the value of P-SENS-P is small, there is a high possibility that dirt is applied to the patch sensor. • This occurs only at a regular timing. When the value of COPIER> DISPLAY> DENS> DENS-S-x is small (2 digits), there is a high possibility that breaking occurred. 1. Check whether the developing assembly and the drum unit are properly installed. 2. Clean the patch sensor (PS21). 3. Check the connection between the patch sensor and the Drum ITB driver PCB (UN6). (Connector, Shorting) Sensor side: J7412, J8035 PCB side: J1907 4. Check open/close operation of the patch shutter. 5. Clean or replace the ITB. • Check whether the ITB belt is dirty or not. If it is dirty, perform cleaning with the service mode (COPIER> FUNCTION> CLEANING> TBLTCLN). • If it is assumed that this error occurred due to scratches on the ITB, replace the ITB. 6. Replace the patch sensor unit. 7. Replace the developing assembly

• Code: E020-0430
• Description: Upper limit error for output of Toner Density Sensor (Bk) at initial installation. When executing the initial installation mode of the Developing Assembly (COPIER > FUNCTION > INSTALL > INISET-K), output failed to reach 128 although the control voltage value of the Toner Density Sensor reached 55 or smaller.
• Remedy: 1. Check the connection between the toner density sensor and the DC controller PCB. (Connector, Breaking (Breaking (shorting))) <Y> sensor side: J7133, J8028, J8087 PCB side: J1244, J8085 <M> sensor side: J7134, J8029, J8088 PCB side: J1244, J8085 <C> sensor side: J7135, J8030, J8089 PCB side: J1244, J8086 <Bk> sensor side: J7146, J8015, J8117 PCB side: J1244, J8080 2. Check whether disconnection or Breaking (Breaking (shorting)) of the toner density sensor occurs or not. 3. Replace the developing assembly