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Mitsubishi MELSEC-A / QnA Discontinued: Spares and Migration to Q or iQ-R

Official discontinuation and service dates

According to Mitsubishi Electric’s MELSEC-A series renewal information, production and service ended as follows:

Mitsubishi notes that only a few large-type items remained in production after September 2006, such as the A61PN and A61RP power supplies and the A6BAT and A8BAT batteries. Mitsubishi’s service period is seven years after production ends, so for most A-series hardware, repair from the manufacturer is no longer available.

Where MELSEC-A is still running

The A and AnS series were standard on Japanese machinery for more than twenty years: injection moulding, presses, textile and packaging lines, automotive welding and assembly, cranes and water treatment. Many of these machines were exported second-hand to Southeast Asia, South Asia, the Middle East and Latin America and are still in daily production.

Modules that fail most often

• Power supplies (A61P, A1S61PN, A1S62PN and similar): aging capacitors and heat.
• CPUs (A1SHCPU, A2SHCPU, A2USHCPU-S1, Q2ASHCPU and others): battery-backed memory loss, worn battery connectors, and program loss after long power-off periods.
• I/O and special modules (A1SX, A1SY, A1S64AD, A1S62DA, A1SD75 positioning): individual channels and output relays.
• Network modules (MELSECNET, A1SJ71 series): hard to replace because the whole network must match.

Checking a used or refurbished A-series module

• Match the exact model and software version printed on the side label; some CPUs differ in instruction support between versions.
• Test on a powered base with a known-good CPU: power-up, RUN/ERROR LEDs, I/O channel test, and parameter read with GX Developer or GPPW.
• Replace the CPU battery on arrival and confirm the program can be written and retained.
• Inspect for corrosion, heat marks and replaced components; ask for test records and a warranty.

Migration options

1. Move to MELSEC-Q or iQ-R: Mitsubishi’s transition guides cover replacing A/QnA systems with Q-series or iQ-R CPUs. GX Works2 can convert many A and QnA programs when you change the PLC type, but special instructions and network settings must be reviewed and tested.
2. Reuse field wiring where possible: Mitsubishi and its partners offer renewal tools and conversion adapters that let new modules connect to existing terminal blocks, which shortens shutdowns. Check the current Mitsubishi transition catalog for the adapters that fit your modules.
3. Phase the work: replace one machine or line at a time, starting with the equipment whose failure costs the most.
4. Bridge with spares: until the migration budget is approved, keep tested spares of every critical module type.

Recommended spares policy

• One tested spare CPU and power supply of each type in use, with a fresh battery.
• One spare of each I/O and special function module type per site.
• Network modules for any MELSECNET or CC-Link link that would stop more than one machine.
• Program backups (GPPW, GX Developer or GX Works2 files) stored off the machine, plus a working programming cable such as an SC-09 type adapter for older ports.

How HOANTRANTDH helps

We source new-surplus and refurbished MELSEC-A, AnS and QnA modules, test them before shipping and supply them with warranty. Our engineers also help with program backup, A-to-Q conversion planning and commissioning support. Browse our Mitsubishi parts catalog, read the obsolete automation parts sourcing guide, or see how we handle Allen-Bradley SLC 500 and PLC-5 spares.