USB 2.0 Troubleshooting

Confirm a standard installation.

This step makes sure the troubleshooting flow below applies to your setup. The Pasif USB 2.0 is flexible and can pass more than USB, but the easy troubleshooting only works for standard installations.

The steps below assume you're running standard USB over a standard USB cable, with a host (computer or hub) on one side and a peripheral (the device being protected) on the other.

The diagnosis gets more complicated in any of these situations:

• You're using our USB Type A/B to terminal block adapter to pass non-USB signals (DC power, RS-232, low-voltage control signaling, etc.). The adapter adds another connection point in the chain, which is another potential failure node.
• You're running cable other than standard USB cable (custom-terminated cable, paired conductors with non-USB pinout, or anything else). Non-standard cable can introduce impedance mismatches or signal-integrity issues that look like a faulty filter.
• You're passing a complex or proprietary protocol over the cable that depends on tight signal timing or specific impedance.

In any of those cases, contact us. We'll work through it with you and figure out whether the filter is the issue or whether it's something else in the installation.

Check the connectors.

This step rules out physical damage at the connectors before testing for cable or filter failure.

Look at the USB connectors on the filter and on each cable. The Pasif USB 2.0 typically has USB Type A on one side and Type B on the other (verify on your specific unit). Make sure connectors are unobstructed and free of any foreign material (lint, dust, or debris in a USB port is a common cause of intermittent connection problems). Reseat both cables firmly.

Verify each cable, the host, and the peripheral individually.

This step verifies that the cables, the host, and the peripheral all work on their own. Once each is confirmed, anything still wrong has to be the filter.

Pull the filter out of the chain. Then test each piece independently:

1. Test the cable from the host to the filter (the cable terminating in the Type-B connector that goes into the filter). Connect the host directly to the peripheral using only that cable. If the peripheral enumerates and works, that cable is fine.
2. Test the cable from the filter to the peripheral (the cable terminating in the Type-A connector at the threaded penetration). Connect the host directly to the peripheral using only that cable. If the peripheral enumerates and works, that cable is fine.
3. Test the host and peripheral together. Connect them with any known-good USB cable rated for USB 2.0 (a longer cable is fine for this test, since we're verifying the host and peripheral, not the original cable). If the peripheral enumerates and works, the host and peripheral are both fine.

If all three tests pass and the system fails when reassembled with the filter in place, the filter is the cause.

If your installation is mounted through a shielded enclosure penetration, you may need to move equipment temporarily or set up a bench test outside the chamber to perform these tests. The verification has to happen; the test is the only way to know.

Contact us.

If Steps 1 through 3 indicate the filter has failed, contact us. Pasif filters cannot be repaired in the field, but they're rarely the failure point. We'll work through it with you and arrange warranty service if the filter is faulty. The Pasif USB 2.0 carries a two-year warranty from the date of first sale.