When an OEM manufacturer needs to replace an LED module in an existing product, the project does not always begin with drawings, Gerber files or a complete BOM.
Sometimes the starting point is simply a photo or an existing sample.
This often raises an important question:
How much can we actually learn from the existing LED module — and what still needs to be defined before a replacement can be developed?
For an OEM replacement project, the objective is not necessarily to copy every component on the old PCB.
The more important question is:
What needs to remain compatible with the existing product, and what can be redesigned?
This distinction matters when an existing housing, mounting structure or electrical interface must remain unchanged, while the LED module itself can be redeveloped for future production.
A Photo Provides Useful Clues — But Not a Complete Specification
A reasonably clear photo can reveal quite a lot about an existing LED module.
For example, NKT may be able to observe:
- approximate PCB shape and dimensions
- LED quantity
- LED package size
- mounting-hole locations
- connector position
- some visible electronic components
These details can help us understand the general construction of the existing module and identify some of the mechanical constraints of the OEM product.
But there are limits.
A photo normally cannot tell us the exact LED manufacturer, part number or bin.
It also may not reveal the actual series-parallel circuit configuration. Sometimes a PCB includes markings that provide useful clues, but without those markings or a physical board to measure, the circuit architecture should not simply be assumed from a photograph.
A photo can provide visual information about an existing module. It does not automatically provide the electrical specification needed to redevelop it.
A Physical Sample Tells Us Much More
When an existing module is available as a physical sample, more information can be measured rather than inferred.
NKT can examine details such as PCB dimensions and thickness, mounting-hole positions, connector type, LED package and component arrangement.
For a working module, electrical and optical measurements can provide additional information.
Depending on the module, these may include:
- operating voltage
- current
- luminous flux
- CCT
- CRI
For a DC module, our engineers can also use electrical measurements to investigate the circuit and determine how the LEDs are connected.
Once the LED quantity and series-parallel configuration are understood, measured module performance can help us estimate how the LEDs are being operated in that particular board.
But this still does not mean that every original component can be identified.
For example, measured module output may help us estimate the approximate output per LED under the module's operating conditions. It does not tell us the original LED manufacturer's datasheet rating, exact part number or bin.
Measured performance and original component specifications are not the same thing.
A physical sample can therefore provide valuable engineering information without being a complete substitute for the original BOM, drawings and design files.
An Unknown AC Module Should Not Simply Be Powered Up for Testing
There is another practical limitation when evaluating an existing module: the original input conditions need to be understood before electrical testing.
This is particularly important for AC modules.
If an AC module was designed for 110V operation, for example, applying 220V simply to determine how it operates could damage the board.
For this reason, when an existing AC module needs to be tested, the customer should provide or confirm its original input voltage.
With DC modules, electrical measurements can often provide more information about the circuit itself, but the module should still be evaluated under appropriate operating conditions.
The objective is to learn from the existing board — not damage the available reference sample while trying to identify it.
What If the Existing LED Module No Longer Works?
OEM replacement projects do not always begin with a functioning sample.
Sometimes the old LED module has already failed.
In that situation, the board may still provide useful mechanical and component information, but normal operating parameters such as lumen output, CCT, CRI, voltage and current may no longer be measurable from the original module.
The project then has to rely more heavily on the information that is still available.
NKT can use the existing PCB, known product requirements and other available information to prepare a preliminary estimate of suitable module parameters.
Those estimated parameters can then be reviewed with the customer.
If the customer agrees that the proposed direction is reasonable, a prototype can be produced and its actual performance measured.
If the original performance requirements are no longer available, prototype testing can help establish a practical performance reference for the new module.
This is different from pretending that every unknown parameter can be recovered accurately from a failed board.
Sometimes it cannot.
What Actually Needs to Stay the Same?
This is often the more useful question in an OEM replacement project.
If the customer's existing product already has a molded housing or fixed mechanical structure, some requirements may be difficult or impossible to change.
For example, the new module may need to maintain the same:
- PCB outline
- mounting-hole positions
- connector or mechanical interface
Electrical and optical performance may also need to remain within an acceptable range, including operating voltage/current and required lumen output, CCT and CRI.
But this does not necessarily mean the replacement board must use the same LED manufacturer, LED part number, LED quantity or internal circuit architecture.
Different LEDs can have different forward voltage, output, efficacy and operating-current characteristics.
As a result, simply reproducing the original LED count with a different LED may not reproduce the original module's performance.
For more detail on this relationship, see how many LEDs a custom LED module should use ?
For an OEM product, the better objective is usually to preserve the mechanical, electrical and optical requirements that matter to the finished product while determining how the new module should achieve them.
The Existing Board Can Be a Reference Without Becoming the New Design
An existing module is sometimes best treated as a reference rather than a design that must be reproduced component by component.
For example, a customer may have an existing AC LED module but decide that a newly developed module can use a DC architecture instead.
In that situation, the original board can still provide valuable information about the physical product and mechanical constraints.
But the new LED selection, quantity, series-parallel configuration, operating voltage/current and other electrical details may be different.
The mechanical requirements may remain much closer to the original module because the replacement still has to fit the existing product.
This is why one of the first questions in an OEM replacement project should be:
Which requirements must remain compatible, and which parts of the module are open to redesign?
The answer determines whether the project is primarily a reproduction of an existing design or a new module developed around an existing product.
Not Every Detail Is Needed Before the First Quotation
There is also a difference between the information needed for a preliminary quotation and the information needed before the final PCB is released.
PCB thickness, for example, may be important when it affects an existing mechanical interface. In other projects, a common PCB thickness can be used as the preliminary quotation basis and confirmed later.
Exact mounting-hole positions are important before the final layout is approved, but they do not necessarily determine the first module price.
If the customer specifies a particular connector, that requirement should be followed. If no connector has been specified yet, NKT may use a connector commonly used in our lighting-module projects as the preliminary basis and confirm the final interface later.
Connector or wire-entry position also needs to work with the customer's housing, but it may not need to be finalized before the first quotation.
LED quantity is another parameter that should not automatically be copied from the existing board.
If the new design uses a different LED model, the appropriate LED quantity may also be different.
The objective of the initial review is therefore not to recover every missing detail before the project can begin.
It is to determine:
Which information affects feasibility and quotation now, and which details need to be confirmed during development?
For a broader explanation of how those requirements move into an actual design, see how OEM requirements become a custom LED module design.
When Should an OEM Send a Physical Sample?
For a completely new LED module, an existing sample may not be necessary at all.
PCB dimensions and the relevant electrical and optical requirements can often provide enough information to begin a preliminary design.
An existing-product replacement can be different.
If the new module needs to remain mechanically and electrically close to the original, but reliable drawings or performance specifications are unavailable, a physical sample can provide much more useful information.
It allows dimensions and interfaces to be measured directly and, if the module still operates, allows its actual electrical and optical performance to be tested.
If the original design files are unavailable, replacing a discontinued LED module without the original design files covers that replacement situation in more detail.
Start With the Information Available From the Existing Product
An OEM does not necessarily need to reconstruct every detail of an old LED module before discussing a replacement project.
A drawing can provide a starting point.
A photo can provide useful visual information.
A physical sample can provide measurable mechanical information and, when it still operates, electrical and optical performance data.
But these sources do not provide the same level of information.
The important step is to separate:
what can be observed,
what can be measured,
what must remain compatible with the existing product,
and what can be redesigned for the new module.
That creates a much more useful starting point for developing a replacement module intended for an existing OEM product and future production.
For OEM manufacturers evaluating an existing LED module for continued production or redesign, discuss your OEM LED module project with NKT.
You can also review custom LED module development for OEM products and NKT's LED module engineering capabilities.