Paul C. Buff, Inc. Technical Forum

As I don't have a spare tube to test at hand, could you tell me if it look like a bad set of tube or a faulty strobe unit:

It's an Ultra 600.
When testing with the test button, I see a dim arc in both tube but no real flash at any power setting.

Should I order another set of tube or ship the unit back for repair?

Tubes will either work or they won't. Most likely, you are not getting a green ready light. These facts would indicate an issue in the charge circuit. Even if you are getting a green light, the cause of the weak triggering would still require a trip in for repair.

The only exception is if there is something plugged into the telephone jack. If the problem does not exist when that is unplugged, but does exist when it is plugged in, then there is a settings issue in the remote being used.