FANUCA20B-1000-0770-01Control Power Supply Unit, Variant -01, for Legacy CNC Control Cage

Product Description

What this part is

A Fanuc A20B-1000-0770 power supply unit, variant -01 — the switching power supply that feeds the logic and control rails of a legacy Fanuc CNC / servo control cage. It converts the incoming AC supply into the regulated DC rails the master board, memory, axis and I/O cards need, and it is the part that fails most often in an old control, because electrolytic capacitors age whether the machine runs or not.

This is the control-side power supply, not a servo or spindle drive power section. Supplied as the power supply unit only.

Decoding the order code

A20B: Fanuc printed-circuit-board and board-level assembly prefix. Fanuc numbers this power supply as a board-level assembly rather than under the A02B control-unit prefix.

1000: the generation group. A20B-1000 and A16B-1000 numbers belong to Fanuc’s earlier CNC and digital-servo generation — the same era as the Series 0 controls and the A06B-6050 / 6057 / 6061 servo units.

0770: the specific unit within that generation.

-01: the build variant of that unit. On Fanuc power supplies the trailing two-digit number distinguishes builds with different rail or input configurations, so it is worth matching. It is a different marker from the /nnX edition suffix seen on Fanuc boards, which is only a revision level.

What these specs mean in practice

Fanuc power supplies of this era look near-identical between variants, mount in the same way and use the same connector families, but the rail set and input arrangement differ — which is why the full number including the -01 is the one that matters, and why the label on the unit being replaced is a better reference than the machine’s nameplate.

Condition: this unit is tested, which on a legacy power supply is worth having.

Quantity and configuration

Sold as 1 piece — one power supply unit, build variant -01. New old stock, in an opened box, tested. Fanuc cage power supplies are fed through a machine-specific harness, which is a separate item sourced to the machine.

Interchange guidance

Searchable equivalents of the same part: A20B-1000-0770-01, A20B10000770-01, A20B-1000-0770, A20B10000770, A20B 1000 0770, A20B-1000-0770/05A. Different editions of the same number are the same unit at a different revision. Other trailing variants of A20B-1000-0770 are related builds rather than equivalents — confirm the rail configuration before substituting one.