MITSUBISHI A-series PLC Troubleshooting Replacement

1. Control cabinet processing

Use conductive metal cabinets to maintain good electrical contact between panels (remove paint).

Flat braided wires are used to connect multiple points between the cabinet door and the main body, reducing high-frequency impedance.

The cross-sectional area of the cabinet grounding wire should be ≥ 22mm ², and the length should be as short as possible.

Cabinet opening diameter ≤ 10cm to prevent high-frequency noise radiation.

2. Connection between power supply and grounding wire

Set up a grounding point near the power module and connect the LG and FG terminals with the shortest wire (≤ 30cm).

For A1S61P/A1S62P/A1S63P, a noise filter needs to be installed at the input end (recommended SCHAFFNER FN343-3/01 or TDK ZHC2203-11).

For CE compatible models (A1S61PEU, A1S62PEU, A1S61PN, A1S62PN), no external filter is required, but LG and FG must be short circuited (unless otherwise specified).

Twist the power cord and ground wire together to enhance common mode noise discharge.

3. Signal cable shielding

All I/O signal lines and communication lines (RS-232C, RS-422, etc.) leading out of the control cabinet must use shielded cables.

The shielding layer contacts the cabinet grounding through a large area of metal clips (welding leads cannot be used due to high high-frequency impedance).

For MELSECNET/II modules (such as A1SJ71AR21), a three coaxial cable must be used and a ferrite magnetic ring (TDK ZCAT3035 is recommended) must be installed at the cable outlet.

The AUI cable of Ethernet module A1SJ71E71-B5 needs to be stripped of insulation and grounded extensively.

Attention: If shielded cables are not used or shielded grounding is poor, the immunity will decrease from 2kV (IEC801-4) to below 1kV, which may cause false signals.

Selection and replacement of power module and I/O module

1. Power module replacement guide

Prototype Number Recommended Replacement (CE Compatible) Remarks

A1S61P (100-120VAC) A1S61PN (100-240VAC) 5V/5A output, requires an external filter

A1S62P (200-240VAC) A1S62PN (100-240VAC) 5V/3A + 24V/0.6A

A1S63P (24VDC input) without CE compatibility model requires external SELV power supply

Replacement precautions:

Overcurrent protection: When the 5V output current exceeds 5.5A (A1S61P) or 3.3A (A1S62P), the power module will automatically turn off the output and turn off the LED. At this point, the load short circuit must be eliminated before power can be restored.

Overvoltage protection: If the 5V voltage rises to 5.5-6.5V, the protection will activate. Power off and then power on to reset. If it still cannot be restored, replace the power module.

Allowable instantaneous power down time: A1S63P is about 20ms under 24VDC input; A1S61P/A1S62P is over 20ms under AC input.

2. Key points for replacing input modules

The rated voltage of AC input modules (such as A1SX10, A1SX20) is 100-120VAC or 200-240VAC. It should be noted that CE compatible models (such as A1SX10EU, A1SX20EU) have a dielectric strength of 1780VAC and the same operating temperature range.

DC input modules (such as A1SX40, A1SX41, A1SX80, etc.) support 12/24VDC, input current 3-7mA, and response time is usually 10ms (high-speed models such as A1SX42 can reach 0.1ms). Attention should be paid when replacing:

Source/Drain Type: The A1SX80 series supports both sink and source connections, while the A1SX40 only supports the sink type.

Response speed: If the original system uses high-speed counting (such as encoder signals), a model with a response time of ≤ 0.2ms (such as A1SX42) must be selected, otherwise pulses will be lost.

3. Output module replacement

Relay output (A1SY10, A1SY14, A1SY18A): Contact capacity 240VAC/24VDC, 2A/point, 8A/common terminal. When replacing, pay attention to the higher dielectric strength (2830VAC) of CE compatible models (A1SY10EU, A1SY14EU, A1SY18AEU). The lifespan of the relay is 20 million mechanical cycles and 100000 electrical cycles (rated load).

Controllable silicon output (A1SY22, A1SY28A): suitable for AC loads, with a response time of approximately 1ms+0.5 cycles. When replacing, pay attention to the load current (0.6A/point, 2.4A/common terminal).

Transistor outputs (A1SY40, A1SY41, A1SY42, etc.): used for DC loads, with a response time of 2ms, and some high-speed types (such as A1SY71) can reach 2ms. Special attention should be paid to:

Output current: A1SY40 is 0.1A/point, A1SY42 is 0.5A/point, A1SY50 is 2A/point. When replacing, be sure to check the original load current to avoid overloading and burning out.

Surge suppression: The transistor output is internally integrated with a Zener diode, but for inductive loads, it is still recommended to use an external parallel freewheeling diode.

Fuse: Most transistor output modules do not come with fuses and require external installation (fast melting is recommended).

Code of practice for electrical wiring

1. Power wiring

Connect the live wire (L) and neutral wire (N) of the AC power supply to the corresponding terminals of the power module. LG is functional grounding, FG is protective grounding. FG must be connected to the grounding bar of the control cabinet.

For A1S63P (24VDC input), an external power supply that complies with SELV (Safety Extra Low Voltage) must be used, with the 24V positive pole connected to "24V" and the negative pole connected to "COM".