Description
Mitsubishi GU-D08 80173-109-01 | Power Flex 7000 Thyristor Board
Product Introduction
The Mitsubishi GU-D08 80173-109-01 is a specialized power-electronics board rather than a conventional PLC or general-purpose communication card. Available industrial-part references identify it as a thyristor board, with Radwell additionally describing the GU-D08 as a communication-integrated type and associating it with a thyristor array.
The part number also appears in legacy equipment records specifically as a Power Flex 7000 communication-integrated GU-D08 thyristor board. That association is important because the board should be evaluated as part of its original power-conversion assembly rather than as an independent generic PCB.
Mitsubishi GU-D08 80173-109-01 is a difficult legacy component to source. Current surplus listings range from used units to new-open-box inventory, while the manufacturer-level lifecycle information available through industrial distributors indicates that the GU-D08 has been discontinued.

GU-D08
Key Technical Specifications
- Manufacturer: Mitsubishi Electric
- Model: GU-D08
- Part Number: 80173-109-01
- Device Type: Thyristor board
- Board Function: Industrial power-control / power-conversion assembly
- Architecture: Communication-integrated type
- Power Semiconductor: Thyristor array
- System Association: Power Flex 7000
- Board Construction: Industrial PCB assembly
- Reported Dimensions: Approximately 209 × 250 × 53 mm
- Application: High-power industrial electrical equipment
- Lifecycle: Discontinued / legacy
- Alternate Mitsubishi Part Reference: 80173-104-01 is also listed as an alternate GU-D08 number in industrial replacement records.
What Can Be Safely Established
The strongest available evidence identifies 80173-109-01 as a Mitsubishi GU-D08 thyristor board. One industrial equipment reference specifically describes 80173-109-01 as a “Power Flex 7000 communication integrated type GU-D08” thyristor board.
I would not publish a specific thyristor voltage, current, gate-drive voltage, or thermal rating for this exact board without the original Mitsubishi schematic or component-level service documentation. Several aftermarket listings use generic language such as “high voltage and current handling capability,” but that is not enough evidence for a precise electrical specification.
Global Sourcing & Live-Test SOP
Because the GU-D08 operates in a high-power semiconductor environment, a visual inspection alone is insufficient.
- Identity verification: Confirm the PCB marking GU-D08 and part number 80173-109-01.
- Revision check: Photograph every PCB label, revision marking, connector designation, and semiconductor marking.
- Physical inspection: Examine the PCB for cracked solder joints, discoloration, carbon tracking, lifted pads, damaged connectors, and evidence of overheating.
- Thyristor inspection: Check the semiconductor packages for cracking, mechanical damage, discoloration, or signs of thermal stress.
- Gate-circuit inspection: Inspect gate-driver components and associated wiring for burned resistors, damaged optocouplers, or degraded connectors.
- Connector inspection: Verify that all board-to-system connectors are mechanically secure and free of oxidation.
- Static semiconductor testing: With the board isolated from all external circuits, perform appropriate diode/thyristor checks according to the applicable service procedure.
- Gate triggering: If the original test procedure permits it, verify gate-drive operation using controlled instrumentation rather than directly improvising a firing circuit.
- System-level test: Install only into the correct Power Flex 7000 hardware configuration and follow the original startup procedure.
- Low-risk commissioning: Where possible, verify control and feedback behavior before applying full power to the connected load.
- Thermal monitoring: Monitor heatsink/semiconductor temperatures during controlled operation.
- Burn-in: For refurbished inventory, perform an extended controlled run under representative operating conditions.
- Final record: Record board revision, semiconductor markings, connector condition, test measurements, and any observed fault history.
A board that looks clean and passes a basic continuity test should not automatically be classified as serviceable. Thyristor assemblies can develop failures that only appear during gate triggering, commutation, high-current operation, or thermal loading.
Field Engineer’s Pitfall Guide
❗ 1. Do not confuse GU-D08 with a standard communication card
The GU-D08 is described as a communication-integrated type, but available records classify the complete assembly as a thyristor board.
Its communication-related circuitry is therefore part of a larger power-electronics function. Treating it as a plug-in communication PCB can lead to incorrect testing and an incomplete replacement assessment.
❗ 2. Do not assume 80173-104-01 and 80173-109-01 are automatically interchangeable
Radwell lists 80173-104-01 as an alternate GU-D08 part reference alongside 80173-109-01.
That is useful procurement information, but it is not sufficient proof of electrical interchangeability in a particular Power Flex 7000 installation. Compare PCB revision, semiconductor arrangement, connectors, gate circuitry, and system documentation before substitution.
❗ 3. Do not bench-test the board by applying arbitrary high voltage
This is a power-semiconductor assembly. The correct test method depends on the original equipment’s gate-drive and power topology.
A Fluke meter can help with preliminary resistance/diode checks, but it cannot establish that the thyristor array will correctly commutate under operating conditions. Use the manufacturer’s service procedure or an appropriately engineered power-electronics test setup for energized testing.
Intent-Driven FAQ
What is Mitsubishi GU-D08 80173-109-01?
It is a Mitsubishi Electric GU-D08 thyristor board, identified in industrial records as a communication-integrated power-control assembly. It is associated with Power Flex 7000 equipment.
Is GU-D08 a PLC module?
No. The available technical records classify it as a thyristor board / industrial power-control PCB, not a conventional PLC CPU or I/O module.
What is the function of the thyristor array?
The thyristor array provides controlled switching of high-power electrical energy within the associated power-conversion system. The exact firing, commutation, and protection scheme depends on the host equipment.
What equipment uses GU-D08?
The available legacy equipment reference associates GU-D08 80173-109-01 with the Power Flex 7000 system.
Before purchasing a replacement, confirm the installed system’s complete equipment model and board location.
Is GU-D08 80173-109-01 discontinued?
Yes. Radwell identifies GU-D08 as discontinued by the manufacturer.
That makes tested surplus, refurbished, and new-old-stock inventory relevant for legacy equipment maintenance.
Are there alternate part numbers?
Industrial replacement records list 80173-104-01 as another GU-D08 reference in addition to 80173-109-01. However, the two should not be assumed interchangeable without hardware and system-level verification.
What should I request from a surplus supplier?
Ask for photographs of the actual GU-D08 PCB, including the Mitsubishi identification label, 80173-109-01 marking, revision information, semiconductor area, and all connectors. For a used board, request evidence of functional testing rather than accepting a power-on-only claim.
Procurement Notes
The Mitsubishi GU-D08 80173-109-01 is a legacy thyristor power-control board associated with Power Flex 7000 equipment. The available evidence supports that identification, but public documentation is too limited to responsibly assign exact semiconductor voltage/current ratings or detailed terminal functions.
For procurement, the safest approach is to match the GU-D08 designation, 80173-109-01 part number, PCB revision, physical connector arrangement, and host-system position. If the application is production-critical, request a documented functional test covering the gate circuitry and power stage—not merely a continuity check.
The supplied eBay listing identifies the item as Mitsubishi GU-D08 80173-109-01. Comparable current listings also show this exact part number being sold as both used and new-open-box inventory, so condition and test evidence should be treated as part of the purchasing specification.


