Part of Obsolete Electronics Replacement & Redesign
Compatible replacement boards: form, fit and function verified in your equipment
Micro Digital Engineering develops replacement boards designed to fit existing equipment without modification, where form, fit and function compatibility is required: the same dimensions and mounting, the same connectors and pinout, the same signals and behaviour. Mechanical, electrical, interface and functional compatibility requirements are agreed before design starts, and each of them is verified — first on the bench against the original, then in the equipment.
Confidential task? We sign an NDA before you share technical files.
Can a replacement board keep the existing connectors and equipment behaviour?
Yes, when these are defined as requirements. Before design starts, we fix what must stay the same — dimensions, mounting points, connectors, pinout, signal levels, timing, power consumption and behaviour, including behaviour in fault conditions — and what may change, such as components or internal circuit design.
Four groups of compatibility requirements
Mechanical
Board outline, mounting points, component heights and keep-out areas, connector positions, heatsinks and any parts that touch the enclosure.
Electrical
Supply voltages and current consumption, signal levels, the loads the board drives, isolation and protection.
Interfaces
Connectors and pinout, communication protocols, signal timing and the behaviour seen by connected equipment.
Functional
Behaviour in normal operation, start-up and shutdown, reactions to faults, indicators and configuration settings.
How each requirement is verified
| Requirement group | What is checked | How it is verified |
|---|---|---|
| Mechanical | Outline, mounting, heights, connector positions | Dimensional check against the original, then fit in the equipment |
| Electrical | Supplies, consumption, signal levels, isolation | Measurements with calibrated equipment, compared with the original |
| Interfaces | Pinout, protocols, timing | Tests with the connected equipment or an equivalent set-up |
| Functional | Operating sequences, fault reactions, indicators | Side-by-side tests with the original on the bench, then in the equipment |
The results are recorded requirement by requirement in the compatibility test report.
What may change inside the board
Components, the internal circuit, the layer count and the firmware implementation may differ from the original, as long as every agreed compatibility requirement is met. What may change is agreed in writing together with what must stay the same.
How the replacement is built
PCB fabrication is performed by specialised manufacturing partners. Prototype component assembly, bring-up, debugging and verification are carried out in-house by our engineering team. Repeat production follows the manufacturing route agreed in the project.
How this differs from related services
| Service | Focus |
|---|---|
| Compatible replacement boards (this page) | One board that must match the original in form, fit and function |
| Obsolete electronics replacement and redesign | The wider project: choosing the route, redesign, modernisation and documentation |
| PCB reverse engineering | Analysis of the original board |
| Schematic and design data reconstruction | Documentation of the original board as it is |
What’s included
Compatibility requirements, analysis of the original, redesign with available components, PCB fabrication through a manufacturing partner, in-house prototype assembly and bring-up, bench tests against the original, tests in the equipment and manufacturing documentation.
What you receive
| Deliverable | Format | How it is checked |
|---|---|---|
| Compatibility requirements | Document: mechanical, electrical, interface, functional | Review and written approval |
| Design files and BOM | Agreed format | Design review, availability check |
| Prototype boards, assembled in-house | The agreed number of boards | Bench tests, then tests in the equipment |
| Compatibility test report | Document, requirement by requirement | Results against each requirement |
| Manufacturing package | Gerber or ODB++, assembly drawings, BOM | Review against the manufacturer’s requirements |
How the work runs
- You confirm that you own the equipment or are authorised to maintain it.
- The original board and its role in the equipment are analysed.
- The compatibility requirements are agreed in writing, including what may change.
- The replacement is designed with available components.
- The bare PCBs are fabricated by a manufacturing partner; the prototypes are assembled and brought up in-house.
- Each requirement is verified on the bench against the original, then in the equipment.
- The design files, test report and manufacturing package are handed over.
What to send us
- Samples of the original board; a working one helps define the behaviour.
- Photos of the board installed in the equipment.
- Equipment documentation and interfaces.
- Confirmation that you own the equipment or are authorised to maintain it.
Common questions
Will the replacement be identical to the original?
It will match the original in every agreed compatibility requirement. Its components and internal design may differ, because the reason for the replacement is usually that the original parts are no longer available.
How is compatibility proven?
By tests against each compatibility requirement, first on the bench and then in the equipment, with acceptance criteria agreed in advance. A test bench can be developed for repeated acceptance tests.
What if we only have a faulty original?
The behaviour is then established from the board’s analysis, the equipment documentation and tests in the equipment. The requirements that cannot be confirmed on a working original are marked as risks in advance.
Can you produce small batches of replacement boards?
The manufacturing package allows repeat production. The manufacturing route and quantities are agreed in the project.
What if the original contains firmware?
Related services
- Obsolete electronics replacement and redesign — the wider replacement project.
- PCB reverse engineering — analysis of the original board.
- Firmware recovery and migration — when the board’s behaviour depends on firmware.
- Test benches and fixtures — acceptance tests for each replacement board.
Discuss a replacement board
Send photos of the board and describe the equipment it works in.
Confidential task? We sign an NDA before you share technical files.