To verify that a power adapter supplier is a real manufacturer rather than a trading company, ask questions only a producer can answer — topology choices, derating at your ambient, behaviour at low mains — then ask which production processes are in-house, request a test record tied to a specific batch, and ask for a sample built to your specification including a non-standard connector. Documents can be borrowed; process answers and batch records usually cannot.
What Is the Difference Between a Manufacturer and a Trading Company?
Definition:
A manufacturer owns the processes that determine the product: PCB assembly, transformer winding where applicable, final assembly, functional test, burn-in where applicable, and packaging. A trading company sells product it does not make, and its technical answers generally route through a third party.
Both structures are legitimate. The practical difference is accountability: who answers for a design change, a process deviation, or a corrective action on your programme.
Which Questions Reveal Whether the Supplier Produces the Product?
Technical depth test:
| Question | Manufacturer-typical answer | Intermediary-typical answer |
| Why was this topology chosen for this power level? | Explains the trade-off directly | Repeats catalogue wording |
| How does derating behave at 55 °C internal ambient? | Gives the position on the derating curve | Quotes the headline rating again |
| What happens to output at the lowest rated mains input? | Describes the behaviour and the dimensioning case | Deflects the question |
| Which protection behaviours are implemented — and how do they recover? | Names OCP/OVP/SCP/OTP and the recovery mode | Lists features without behaviour |
| Which critical components are second-sourced? | Names component families and the rationale | “All components are high quality” |
How Do You Verify Production Processes Remotely?
Verification steps:
- Ask which processes are in-house — SMT, winding, assembly, test, packaging — and which are outsourced, and to whom.
- Request a batch-level test record, dated and tied to a specific lot, rather than a generic datasheet.
- Ask for a sample to your specification, including a connector or cable that is not in the catalogue. A producer can build it; an intermediary proposes an alternative.
- Ask about traceability — how a finished unit and its packaging are identified, and how far back records reach.
- Ask for a process walk-through of the critical stations, including what happens to a failing unit.
What Documents Should You Request?
| Document | What it proves | What it does not prove |
| Business licence | Legal entity exists | Who manufactures the product |
| Quality system certificate | A system is certified, within a stated scope | That your product was built under it |
| Safety/EMC certificate | A specific model and configuration was evaluated | Coverage of your model or market |
| Batch test record | Units in that lot were tested to defined limits | Performance outside those limits |
| Material declarations | Component and material information for a configuration | That the configuration is unchanged |
Rule: read the scope of every document. Scope is where the useful information is.
How Does a Site Visit or Third-Party Audit Fit In?
Where programme risk justifies it, physical verification is stronger evidence:
- A site visit lets you see the lines your product would run on, the test stations, and the storage of components and finished goods.
- A third-party audit adds an independent record, and is useful where you cannot visit or where several suppliers must be compared consistently.
- Where neither is practical, the remote path above still separates most intermediaries — a trader can produce documents, but rarely coherent process answers and batch records for a specific product.
What Signals Indicate an Intermediary?
- Technical answers that ignore the operating conditions you supplied.
- Certificates that never name a model or configuration.
- Samples that always correspond to an existing catalogue item.
- No lot or batch identification on the product or packaging.
- Change requests that cannot be assessed — no answer to “what does this change touch?”.
Frequently Asked Questions
Can a trading company be a good supplier?
It can be, particularly where it adds real value in sourcing, coordination or quality control. The management approach differs: you have to be explicit about who is accountable for design changes and process deviations, and require the same evidence you would from a manufacturer.
How do I verify a certificate’s scope?
Ask for the document itself and read which model, configuration, standard and market it covers — then confirm it matches your requirement. Certification is available by model, not across a range.
What verification is realistic without a site visit?
Process questions, batch records, sample behaviour and traceability questions. These are hard to answer consistently without production knowledge, so they filter most intermediaries.
How often should verification be repeated?
Re-verify when the relationship changes materially — new product, new site, a change of key personnel, or a quality event. Verification is a baseline, not a one-off.
Is a factory audit always necessary?
It depends on programme risk, order value and how critical the product is. The pre-order audit checklist is useful as a structure even where a formal audit is not performed.
Next Step
Request a quote — “Tell us your requirement; we will respond with the specification and the evidence that applies to it.”