{"id":1070,"date":"2026-09-01T15:28:50","date_gmt":"2026-09-01T07:28:50","guid":{"rendered":"https:\/\/www.paiyipower.com\/?p=1070"},"modified":"2026-09-09T13:12:40","modified_gmt":"2026-09-09T05:12:40","slug":"how-to-test-power-supply","status":"publish","type":"post","link":"https:\/\/www.paiyipower.com\/pt\/how-to-test-power-supply\/","title":{"rendered":"Como Testar uma Fonte de Alimenta\u00e7\u00e3o: Guia Completo para Engenheiros e Equipes de QC"},"content":{"rendered":"<h1>How to Test a Power Supply: A Complete Guide for Engineers and Buyers<\/h1>\n<p><strong>Published:<\/strong> September 2026<br \/>\n<strong>Reading time:<\/strong> 9 min<br \/>\n<strong>Audience:<\/strong> hardware engineers, QA teams, and B2B buyers verifying external power adapters and chargers before approval or incoming inspection<\/p>\n<p><strong>By Han &#8212; Paiyi Power<\/strong>, a power adapter manufacturer running ATE functional test, burn-in and 100% inspection on external supplies from 5W to 240W.<br \/>\n<strong>Last updated: 8 September 2026.<\/strong><\/p>\n<hr>\n<div class=\"wp-block-rank-math-toc-block\" id=\"rank-math-toc\" style=\"background:#f5f7f8;border:1px solid #d9dee3;border-radius:6px;padding:16px 20px;margin:28px 0;\">\n<h2 style=\"font-size:18px;margin:0 0 10px;border:none;padding:0;\">Contents<\/h2>\n<nav>\n<ul style=\"margin:0;padding-left:20px;\">\n<li style=\"margin:4px 0;\"><a href=\"#direct-answer-how-do-you-test-a-power-supply\">Direct answer: how do you test a power supply?<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#three-different-jobs-all-called-testing-a-power-supply\">Three different jobs all called \u201ctesting a power supply\u201d<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#safety-first\">Safety first<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#tools-you-need\">Tools you need<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-1-visual-and-mechanical-inspection\">Test 1: visual and mechanical inspection<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-2-no-load-output-voltage\">Test 2: no-load output voltage<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-3-loaded-voltage-and-load-regulation\">Test 3: loaded voltage and load regulation<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-4-ripple-and-noise\">Test 4: ripple and noise<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-5-efficiency-and-no-load-power\">Test 5: efficiency and no-load power<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-6-protection-functions\">Test 6: protection functions<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-7-thermal-behaviour-and-burn-in\">Test 7: thermal behaviour and burn-in<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#test-8-safety-and-emc-lab-only\">Test 8: safety and EMC (lab only)<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#what-to-ask-your-supplier-for\">What to ask your supplier for<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#frequently-asked-questions-about-testing-a-power-supply\">Frequently asked questions about testing a power supply<\/a><\/li>\n<li style=\"margin:4px 0;\"><a href=\"#sources\">Sources<\/a><\/li>\n<\/ul>\n<\/nav>\n<\/div>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"direct-answer-how-do-you-test-a-power-supply\">Direct answer: how do you test a power supply?<\/h2>\n<p><strong>Test it in this order: visual inspection, no-load voltage, loaded voltage (load regulation), ripple and noise, efficiency and no-load draw, protection behaviour, then thermal burn-in.<\/strong> A supply that shows the correct voltage on a multimeter with nothing connected has passed only the easiest of the seven checks. Most field failures come from tests three, four and six &#8212; the output sagging under load, excess ripple upsetting the load circuit, or a protection function that latches instead of recovering. Safety dielectric (hi-pot) testing is an eighth check, but it belongs in a controlled lab, not on a bench. Below is the full sequence, the pass\/fail limits we use, and which tests a buyer can realistically run versus which belong at the factory.<\/p>\n<hr>\n<figure style=\"width: 768px\" class=\"wp-caption alignnone\"><img fetchpriority=\"high\" decoding=\"async\" class=\"size-large wp-image-1082\" src=\"https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-ate-test.webp\" alt=\"how to test a power supply: ATE functional test of external power adapters at Paiyi Power\" width=\"768\" height=\"576\" srcset=\"https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-ate-test.webp 1600w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-ate-test-300x225.webp 300w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-ate-test-1024x768.webp 1024w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-ate-test-768x576.webp 768w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-ate-test-1536x1152.webp 1536w\" sizes=\"(max-width: 768px) 100vw, 768px\" \/><figcaption class=\"wp-caption-text\">Automated test equipment checks voltage, load and protection on every unit<\/figcaption><\/figure>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"three-different-jobs-all-called-testing-a-power-supply\">Three different jobs all called &#8220;testing a power supply&#8221;<\/h2>\n<p>Before choosing a method, be clear which question you are answering &#8212; the test set differs.<\/p>\n<table style=\"border-collapse: collapse; width: 100%; margin: 18px 0; font-size: 15px;\">\n<thead>\n<tr>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Goal<\/th>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Who does it<\/th>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Core checks<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Design validation<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Manufacturer engineering<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Full electrical, thermal, safety, EMC<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Production QC<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Factory line (ATE + burn-in)<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Voltage, load, protections, 100% functional<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Incoming inspection<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Buyer \/ brand QC<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Visual, no-load and loaded voltage, sample ripple<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>This guide is written primarily for <strong>external power supplies<\/strong> &#8212; wall-mount and desktop adapters &#8212; which is what we build. The same logic applies to internal supplies with the obvious difference that you are working inside a chassis.<\/p>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"safety-first\">Safety first<\/h2>\n<ul>\n<li><strong>Never open a supply that is plugged in<\/strong>, and never touch the primary side even when unplugged &#8212; the bulk capacitor can hold a lethal charge for minutes.<\/li>\n<li><strong>Use an isolation transformer<\/strong> when probing anything mains-referenced, and a residual-current device on the bench.<\/li>\n<li><strong>Do not attempt dielectric (hi-pot) testing<\/strong> without training and fixtures. It applies kilovolts and is a lab procedure.<\/li>\n<li><strong>Sizing matters:<\/strong> an electronic load must be rated above the adapter&#8217;s output and able to dissipate the heat. 240W at full load is a lot of heat in a small box.<\/li>\n<\/ul>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"tools-you-need\">Tools you need<\/h2>\n<table style=\"border-collapse: collapse; width: 100%; margin: 18px 0; font-size: 15px;\">\n<thead>\n<tr>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Tool<\/th>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">What it tells you<\/th>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Notes<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Digital multimeter<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">DC output voltage, continuity<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Enough for tests 1&#8211;2 only<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Electronic load<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Behaviour under real current draw<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Constant-current mode; mind the watt rating<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Oscilloscope<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Ripple, noise, transient response<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Use 20 MHz bandwidth limit; short ground path<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>AC power meter<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Input power, efficiency, no-load draw<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Needs true RMS and low-current resolution<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Thermocouple \/ IR camera<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Case and component temperature<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">For burn-in and derating checks<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-1-visual-and-mechanical-inspection\">Test 1: visual and mechanical inspection<\/h2>\n<p>Catch the obvious before powering anything: cracked or deformed housing, damaged strain relief, bent or recessed connector pins, incorrect label (output voltage, polarity, current), mismatched plug type for the target market, and poor seam or flash on the enclosure. On a USB-C adapter, check that the receptacle is not loose. A surprising share of &#8220;electrical&#8221; failures are mechanical.<\/p>\n<h2 style=\"border-bottom: 2px solid #d9dee3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-2-no-load-output-voltage\">Test 2: no-load output voltage<\/h2>\n<p>With nothing connected, measure the output. It should sit within the stated tolerance &#8212; <strong>typically &#177;5%<\/strong> for general-purpose adapters, tighter (&#177;1&#8211;3%) for medical, industrial and many non-standard designs. Consider:<\/p>\n<ul>\n<li>Correct polarity on barrel connectors (centre-positive is common but <em>not<\/em> universal).<\/li>\n<li>A supply reading 0V may be a protection latch rather than a dead unit.<\/li>\n<li>On USB-C, a supply with no device attached may output 0V until a valid sink negotiates. That is normal PD behaviour, not a fault &#8212; you need a PD trigger or analyser to see the voltage.<\/li>\n<\/ul>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-3-loaded-voltage-and-load-regulation\">Test 3: loaded voltage and load regulation<\/h2>\n<p>This is the test that separates a good supply from a plausible one. Load the output to 25%, 50%, 75% and 100% of rated current and record the voltage at each step. The voltage should stay inside tolerance and should not drift steadily downward as load increases &#8212; that drift signals inadequate design margin or a genuinely undersized unit.<\/p>\n<table style=\"border-collapse: collapse; width: 100%; margin: 18px 0; font-size: 15px;\">\n<thead>\n<tr>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Check<\/th>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Typical acceptance<\/th>\n<th style=\"border: 1px solid #d9dee3; padding: 9px 11px; background: #f5f7f8; text-align: left;\">Why it matters<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Output voltage<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Within &#177;5% of nameplate (tighter if specified)<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Out-of-tolerance supply stresses the load<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Load regulation<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Holds tolerance from no-load to full load<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Drift indicates thin design margin<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Ripple and noise<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Typically under 1&#8211;2% of output (20 MHz BW)<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Upsets analogue, RF and measurement circuits<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>Transient response<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Recovers within tolerance after a load step<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Poor recovery causes unexplained resets<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\"><strong>No-load power<\/strong><\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Meets DOE Level VI \/ EU ErP limits<\/td>\n<td style=\"border: 1px solid #d9dee3; padding: 9px 11px;\">Legal requirement in most markets<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-4-ripple-and-noise\">Test 4: ripple and noise<\/h2>\n<p>Set the oscilloscope to <strong>AC coupling<\/strong>, enable the <strong>20 MHz bandwidth limit<\/strong>, and probe as close to the output terminals as possible. Do <em>not<\/em> use the long alligator-clip ground lead that ships with most probes &#8212; it acts as an antenna and will show you switching noise that is not really there. Use a tip-and-ring or coaxial connection, or a dedicated probe tip adapter, and load the output while measuring.<\/p>\n<p>Excess ripple is a design issue, not a tolerance issue: a supply can be perfectly on-voltage and still be unusable for audio, RF, or precision measurement. If your application is sensitive, specify a ripple limit in your purchase spec rather than relying on a generic figure.<\/p>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-5-efficiency-and-no-load-power\">Test 5: efficiency and no-load power<\/h2>\n<p>Efficiency is output power divided by input power, measured with a true-RMS AC meter. Standards-based testing averages efficiency across several load points rather than quoting a single best case. No-load (standby) consumption is a separate legal limit and is where weak designs show up. Current requirements are covered in detail in our guide to <a href=\"https:\/\/www.paiyipower.com\/external-power-supply-efficiency-standards\/\">external power supply efficiency standards<\/a>, including DOE Level VI, EU ErP (Reg. (EU) 2019\/1782) and voluntary CoC Tier 2.<\/p>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-6-protection-functions\">Test 6: protection functions<\/h2>\n<p>Deliberately trigger each protection and confirm the behaviour matches the specification. This is the step most buyers skip, and it is where the difference between a commodity and an engineered supply is clearest.<\/p>\n<ul>\n<li><strong>Over-current (OCP):<\/strong> raise the load past the rating. The supply should limit or shut down rather than overheat.<\/li>\n<li><strong>Short-circuit (SCP):<\/strong> short the output. It should survive, then either recover or latch &#8212; as specified. Confirm which, because a latching supply looks &#8220;dead&#8221; to an end user.<\/li>\n<li><strong>Over-voltage (OVP):<\/strong> usually verified by the manufacturer on the bench, since forcing it can destroy the unit.<\/li>\n<li><strong>Over-temperature (OTP):<\/strong> run the unit hot in a chamber; it should reduce or cut output, then recover.<\/li>\n<\/ul>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-7-thermal-behaviour-and-burn-in\">Test 7: thermal behaviour and burn-in<\/h2>\n<p>Run the supply at or near full load in a warm environment and watch the case temperature over several hours. What you are looking for is <strong>stability<\/strong>: the output should not sag and the temperature should plateau. Burn-in is standard practice precisely because early failures cluster in the first hours of operation &#8212; which is why a factory that ships without it pushes that risk onto the customer.<\/p>\n<figure style=\"width: 768px\" class=\"wp-caption alignnone\"><img decoding=\"async\" class=\"size-large wp-image-1083\" src=\"https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-aging-chamber.webp\" alt=\"Aging test chamber rack for burn-in of power adapters at Paiyi Power\" width=\"768\" height=\"348\" srcset=\"https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-aging-chamber.webp 1600w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-aging-chamber-300x136.webp 300w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-aging-chamber-1024x465.webp 1024w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-aging-chamber-768x348.webp 768w, https:\/\/www.paiyipower.com\/wp-content\/uploads\/2026\/09\/pyi-factory-aging-chamber-1536x697.webp 1536w\" sizes=\"(max-width: 768px) 100vw, 768px\" \/><figcaption class=\"wp-caption-text\">Burn-in under load: early-life failures are caught before shipment<\/figcaption><\/figure>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"test-8-safety-and-emc-lab-only\">Test 8: safety and EMC (lab only)<\/h2>\n<p>These are not bench tests. Dielectric withstand (hi-pot), insulation resistance, and conducted\/radiated emissions require calibrated equipment and a controlled environment, and they are what CE, CB and FCC markings rest on. Ask the manufacturer for the model-specific test report rather than trying to replicate it. The relevant safety baseline for IT and AV equipment is <strong>IEC\/EN 62368-1<\/strong>.<\/p>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"what-to-ask-your-supplier-for\">What to ask your supplier for<\/h2>\n<ol>\n<li>A <strong>test report per SKU<\/strong> covering output, load regulation, ripple, efficiency and protections.<\/li>\n<li>The <strong>derating curve<\/strong> &#8212; continuous output versus ambient temperature.<\/li>\n<li><strong>Burn-in policy<\/strong>: duration, load level, and what percentage of units receive it.<\/li>\n<li><strong>Inspection level<\/strong>: whether every unit is functionally tested or only sampled.<\/li>\n<li><strong>Certificates<\/strong> with numbers you can verify (CE, CB, FCC, ISO 9001).<\/li>\n<\/ol>\n<p>At Paiyi Power, every unit is functionally tested on ATE and inspected before shipment, under an ISO 9001 quality system. If you are comparing suppliers on more than price, our article on <a href=\"https:\/\/www.paiyipower.com\/power-adapter-manufacturer-vs-trading-company\/\">manufacturer vs trading company vs big OEM<\/a> explains why the testing regime differs so much between them, and <a href=\"https:\/\/www.paiyipower.com\/power-adapter-cost-transparency\/\">power adapter cost transparency<\/a> shows what that testing actually costs per unit at different volumes.<\/p>\n<hr>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"frequently-asked-questions-about-testing-a-power-supply\">Frequently asked questions about how to test a power supply<\/h2>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">Can I test a power supply with just a multimeter?<\/h3>\n<p><strong>Partly.<\/strong> A multimeter confirms the no-load voltage and not much else. Load regulation, ripple and protection behaviour all need a load, a scope, or both.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">Why does my adapter show 0V on USB-C?<\/h3>\n<p><strong>Often it is not faulty.<\/strong> USB Power Delivery supplies output 0V until a device negotiates a contract. Use a PD trigger or analyser to see the voltage.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">What voltage tolerance is acceptable?<\/h3>\n<p><strong>&#177;5% is the common general-purpose figure<\/strong>, with &#177;1&#8211;3% typical for medical, industrial and non-standard designs. Always specify it in your purchase spec.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">How much ripple is too much?<\/h3>\n<p><strong>As a rule of thumb, under 1&#8211;2% of output<\/strong> measured with a 20 MHz bandwidth limit and a short ground path. Sensitive analogue or RF loads need a tighter, explicitly specified limit.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">Is it safe to open an adapter to test it?<\/h3>\n<p><strong>Not while it is connected, and not casually afterwards.<\/strong> The primary-side capacitor can retain a lethal charge after unplugging. Use an isolation transformer and treat the primary side as live.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">What is burn-in and why does it matter?<\/h3>\n<p><strong>Running units under load for hours before shipment.<\/strong> Early-life failures cluster in the first hours of operation, so burn-in moves that risk from your customer back to the factory.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">Should I hi-pot test incoming adapters myself?<\/h3>\n<p><strong>No.<\/strong> Dielectric testing applies kilovolts and belongs in a controlled lab with the right fixtures. Request the manufacturer&#8217;s report instead.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">What does 100% inspection actually mean?<\/h3>\n<p><strong>Every unit is functionally tested<\/strong>, not a statistical sample. Ask whether the claim covers ATE testing, burn-in, or visual inspection only &#8212; the three are often conflated.<\/p>\n<h3 style=\"margin-top: 24px; color: #2f6b4f;\">Can you test a custom or non-standard adapter?<\/h3>\n<p><strong>Yes, and the test plan should be written into the project.<\/strong> Custom voltages and connectors need their own limits agreed up front. See <a href=\"https:\/\/www.paiyipower.com\/non-standard-power-adapter-engineering\/\">non-standard power adapter engineering<\/a>.<\/p>\n<hr>\n<h2 style=\"border-bottom: 2px solid #1264a3; padding-bottom: 6px; margin-top: 36px;\" id=\"sources\">Sources<\/h2>\n<ul>\n<li><a href=\"https:\/\/www.usb.org\/\" target=\"_blank\" rel=\"noopener\">USB-IF &#8212; USB Power Delivery specifications<\/a><\/li>\n<li><a href=\"https:\/\/www.iec.ch\/\" target=\"_blank\" rel=\"noopener\">IEC 62368-1 and IEC 62680 &#8212; safety and USB Power Delivery standards<\/a><\/li>\n<li><a href=\"https:\/\/www.energy.gov\/eere\/buildings\/external-power-supplies\" target=\"_blank\" rel=\"noopener\">U.S. DOE &#8212; External Power Supply efficiency (Level VI)<\/a><\/li>\n<li><a href=\"https:\/\/energy.ec.europa.eu\/topics\/energy-efficiency\/energy-efficient-products\/ecodesign-and-energy-labelling-regulation-and-directives_en\" target=\"_blank\" rel=\"noopener\">EU Commission &#8212; Ecodesign \/ ErP for external power supplies<\/a><\/li>\n<li><a href=\"https:\/\/www.iso.org\/iso-9001-quality-management.html\" target=\"_blank\" rel=\"noopener\">ISO &#8212; ISO 9001 quality management systems<\/a><\/li>\n<\/ul>\n<p><!-- faq-schema-v1 --><script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Can I test a power supply with just a multimeter?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Partly. A multimeter confirms the no-load voltage and not much else. Load regulation, ripple and protection behaviour all need a load, a scope, or both.\"}},{\"@type\":\"Question\",\"name\":\"Why does my adapter show 0V on USB-C?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Often it is not faulty. USB Power Delivery supplies output 0V until a device negotiates a contract. Use a PD trigger or analyser to see the voltage.\"}},{\"@type\":\"Question\",\"name\":\"What voltage tolerance is acceptable?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"\u00b15% is the common general-purpose figure, with \u00b11\u20133% typical for medical, industrial and non-standard designs. Always specify it in your purchase spec.\"}},{\"@type\":\"Question\",\"name\":\"How much ripple is too much?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"As a rule of thumb, under 1\u20132% of output measured with a 20 MHz bandwidth limit and a short ground path. Sensitive analogue or RF loads need a tighter, explicitly specified limit.\"}},{\"@type\":\"Question\",\"name\":\"Is it safe to open an adapter to test it?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Not while it is connected, and not casually afterwards. The primary-side capacitor can retain a lethal charge after unplugging. Use an isolation transformer and treat the primary side as live.\"}},{\"@type\":\"Question\",\"name\":\"What is burn-in and why does it matter?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Running units under load for hours before shipment. Early-life failures cluster in the first hours of operation, so burn-in moves that risk from your customer back to the factory.\"}},{\"@type\":\"Question\",\"name\":\"Should I hi-pot test incoming adapters myself?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. Dielectric testing applies kilovolts and belongs in a controlled lab with the right fixtures. Request the manufacturer's report instead.\"}},{\"@type\":\"Question\",\"name\":\"What does 100% inspection actually mean?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Every unit is functionally tested, not a statistical sample. Ask whether the claim covers ATE testing, burn-in, or visual inspection only \u2014 the three are often conflated.\"}},{\"@type\":\"Question\",\"name\":\"Can you test a custom or non-standard adapter?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes, and the test plan should be written into the project. Custom voltages and connectors need their own limits agreed up front. See non-standard power adapter engineering.\"}}]}<\/script><\/p>\n","protected":false},"excerpt":{"rendered":"<p>How to Test a Power Supply: A Complete Guide for Engineers and Buyers Published: September 2026 Reading time: 9 min Audience: hardware engineers, QA teams, and B2B buyers verifying external power adapters and chargers before approval or incoming inspection By Han &#8212; Paiyi Power, a power adapter manufacturer running ATE functional test, burn-in and 100% [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":1082,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-1070","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-services"],"_links":{"self":[{"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/posts\/1070","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/comments?post=1070"}],"version-history":[{"count":4,"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/posts\/1070\/revisions"}],"predecessor-version":[{"id":1271,"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/posts\/1070\/revisions\/1271"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/media\/1082"}],"wp:attachment":[{"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/media?parent=1070"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/categories?post=1070"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.paiyipower.com\/pt\/wp-json\/wp\/v2\/tags?post=1070"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}