How to Use This Tool
- Choose the failed function and the cable connector.
- Read the exact cable specification and record known data or video support.
- Repeat the same task with a known-good cable, changing only the cable.
- Enter the comparison outcome and follow the result for that function.
Calculation Method
This guided checker compares your stated symptom, documented cable capability and cable-swap outcome. It does not access the cable, test its conductors or read an electronic marker. An unknown specification stays unknown. A result describes the evidence you entered rather than certifying the cable.
Worked Example
A phone charges but does not appear on the computer. The same unlocked phone and USB port transfer files with a documented data cable. The original cable is suspect for that task; the result does not distinguish missing data capability from damage.
Start with One Failed Function
Select power when the device does not charge, data when a storage device or phone is not detected, and video when an external display receives no picture. Run separate checks for separate symptoms. A dock that charges a laptop but has a blank monitor has passed only part of the connection task.
Record the two endpoints, the exact port and what failed before moving anything. “USB did not work” hides the distinction between no detection, an interrupted transfer and a display using the wrong input. Those observations lead to different checks.
Read Capability Separately from Connector Shape
USB-A, USB-B, Micro-USB and USB-C describe connectors. They do not give a complete performance specification. Find the cable model, stated data rate and supported power. For a USB-C display connection, check the intended display protocol as well. A plain USB-A connection does not carry native DisplayPort Alt Mode. USB graphics products that require software are a different arrangement.
Apple documents a useful distinction: its USB-C Charge Cable in the cited comparison supports USB 2.0 data but no video. The cited Thunderbolt cable supports additional modes. Neither example defines every cable with a similar appearance. Enter unknown when the exact product specification cannot be found.
Make the Comparison Repeatable
Begin with a setup that already performs the task. Keep the same host port, accessory, charger where relevant, and display mode. Remove optional adapters when the direct connection is supported. Replace only the cable, then repeat the original task. A comparison cable must be documented for that task, not merely able to charge another device.
For data, unlock the phone and approve the appropriate file-transfer or trust prompt. For video, select the correct monitor input and begin with a documented supported resolution. Note whether the original cable fails again after the comparison succeeds. An intermittent fault needs more than one observation.
Interpret the Comparison Without Overstating It
A replacement that works makes the original cable a stronger suspect. It does not reveal the internal fault. A cable outside the required specification and a damaged cable can produce the same symptom. The next useful action is to check the product rating or replace it with a documented suitable cable.
| Observation | Useful interpretation |
|---|---|
| Comparison works; original fails | Original cable is suspect for the selected task. |
| Both fail | No working baseline; investigate the port, device and configuration. |
| Both cables work | Fault was not reproduced; no general pass certification. |
| Comparison not tested | Capability check only; a controlled swap remains outstanding. |
Keep Software and Dock Limits in the Investigation
A phone set to charging only may hide its files even with a functioning data cable. A display can fail because the host port lacks video, the dock uses a different protocol, or the requested mode exceeds the documented setup. Follow the relevant device instructions before concluding that the cable is defective.
Label a working cable by the task actually confirmed, such as a particular backup drive or monitor setup. Preserve its published rating separately. This prevents a basic data success from becoming an unsupported claim about every dock, charging power or display mode.
What the Result Means
No browser test here measures voltage, current, resistance, cable speed or video bandwidth. A successful charging session proves neither data nor display support. Stop using cables with exposed conductors, heat damage or a loose plug; do not probe powered connectors.
Common Questions
Does USB-C Mean the Cable Supports Video?
No. Read the exact cable and host specifications. Charging wattage and basic USB data support do not establish a video path.
Can a Successful File Copy Prove the Advertised Speed?
No. The host, drive, file mix and software can limit a copy. This checker records a controlled functional comparison, not a certified speed test.
Why Is the Result Unresolved When Both Cables Fail?
The port, device, settings or comparison cable may be involved. A working baseline is needed before a cable swap can isolate the fault.