Harman JBL Professional VTX Series, Руководство пользователя

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VTX B 15 | User Manual
11 - SYSTEM TESTING
As with all speakers, the B15 must be checked and maintained periodically in order to assure long-term performance. While the system
is designed to exhibit the utmost reliability, ensuring optimal performance for years to come requires confirming that the B15 is operat-
ing within specified tolerances. Below are two methods of checking and verifying proper transducer performance in a VTX B15 system.
11.1 USING A DMM (DIGITAL MULTIMETER)
This method is best suited for when the speaker system can be tested in the shop. A DCR (DC resistance) test with a multimeter can
give a very accurate reading of whether transducers are properly wired and operating within standard tolerances. This test is appropriate
only for individual enclosures, not groups of cabinets.
With the B15 unconnected from any amplifier, set a DMM to the resistance (Ω) setting, set the B15 pin selection switch to the “A” position
and place the probes across the Pin1+/- outputs . Record the values indicated on the DMM for the leads and refer to the chart below to
determine if the DCR readings are within tolerance.
Notes:
• The DCR numbers listed above assume the transducers are at room temperature. If a measurement is taken right after use when
the transducers are warm, readings may vary. For best results, test the speakers cold.
• The DCR value of a transducer gives an accurate representation of its electrical state. Mechanical defects will not be indicated by
this test. Refer to the VTX B15 Service Manual for instructions on performing a rub-and-buzz test using a sine wave generator.
VTX B15
DCR Tolerance
Good B15 5.0 Ω +/- 0.2 Ω
Driver shorted 0.2 Ω -